Category

Nutrition

Research Review: The Effect Of Sleep On Diet

Keiron - Sleep and Diet

In this article, our expert Dr. Kieron Rooney – reviews: Effect of sleep duration on dietary intake, desire to eat, measures of food intake and metabolic hormones: A systematic review of clinical trials, led by  Samira Soltanieh From the Department of clinical nutrition and dietetics, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

 

1) What was the high-level summary of the research? 

Individuals that have their sleep disrupted or who report naturally shorter sleep duration are more likely to also eat more. It is difficult to pinpoint exactly what they eat more of, but in general, adults seem to snack on foods with higher fat content and teenagers on higher glycemic index (GI) sweet foods.  

2) What did the study try to measure? 

This study sought out as many studies as possible in which a person’s sleep duration and dietary habits were investigated. They then explored if there was any association between what people ate with how long they slept. 

3) How was the study undertaken? 

This study is referred to as a systematic review. The authors themselves did not implement a study in which they collected data from individuals with disturbed sleep. Instead, they searched for, identified, and synthesised studies that met their inclusion criteria, which had already been conducted by other investigators. 

The authors found over 700 studies and ended up identifying 50 studies that reported both food intake and sleep duration; 43 of these studies were on adults. Once the review authors had found these studies, they looked at the dietary data to see what the individuals in those studies were eating, and, how long they slept for. They also looked for any studies that reported on hunger and/or appetite and any studies that may have measured hormones believed to influence what humans eat.

4) What did the study find? 

The main result the authors focused on here was total energy intake. This was reported in 30 of the 50 studies they found. Most studies – 19 of the 30 – associated short sleep duration with a tendency to overeat. While some studies showed this was a result of eating larger meals other studies reported that it was a result of more snacks being eaten throughout the day. There was no clear indicator of which – larger meals or more snacks – was likely to be common in specific people.

There was also no clear indication as to which macronutrients – fat, protein, or carbohydrate – may have been contributing to the excess energy being consumed. The authors summarised the studies and suggested the extra energy was coming from either fat or protein rather than carbohydrates, yet the results were very much 50/50 on this. A big reason for the lack of clarity here is that the review included studies that induced sleep deprivation from as short as 1 night by keeping people awake with entertainment and keeping lights on all night compared to other studies in which sleep was restricted for over a month to only 6 hours a night.

5) Is there any other research out there that supports these findings or contradicts it? 

Absolutely, a 2017 systematic review was published that looked only at studies in which sleep was partially disturbed with reduced hours in bed. That review contained only 17 studies but they were so similar in design that the authors performed a meta-analysis. This is where the individual study results from each study are mathematically combined for each intervention, rather than simply being summarised such as in the present study. The smaller but more mathematically robust systematic review reported that even just partial sleep reduction of a couple of hours a night resulted in much greater energy intake with no effect on energy expenditure which was then concluded to lead to weight gain.

6) How much weight should we give this research?

This study is interesting and contains nearly three times the number of studies as the 2017 paper. However, the results of these studies are summarised rather than analysed and as such are very much open to interpretation. Despite this, this study provides a great resource for the complete repository of studies investigating the association between our diets and our sleep duration.

7) What does this mean for your work/research/industry? 

For me, I think this is interesting in the context of understanding why some people may find themselves eating more processed snacks than others. The big question that still needs answering is whether or not it is the disrupted sleep that promotes individuals to snack and eat more, or it’s the eating more that then disrupts sleep.

8) What’s the key takeaway for us to take from this research?

If you are looking for simple ways to cut your intake of processed high-energy snacks – get more than 6 hours of sleep a night! 

9) Will you be doing anything differently because of this research? 

Not so much differently – but perhaps I will start taking more sleep history surveys in my diet intervention studies.

 

Dr. Kieron Rooney completed his PhD in the Department of Biochemistry, within the Faculty of Science at the University of Sydney. Kieron’s primary interest focuses on conducting research and using this research to educate others on how what we eat, influences our metabolism. 

Research Review: Ultra-Processed Food and Mortality

In this article, our expert Dr Kieron Rooney – Associates Professor at The University of Sydney & nationally recognised expert in nutrition research – reviews Ultra-processed food intake and all-cause mortality: DRECE cohort study by Ferreiro et al. 2021, and breaks it down to give us the vital parts we need to know. 

 

1) What was the high-level summary of the research?

The risk of dying increases with the amount of ultra-processed food products in one’s diet.

 

2) What did the study try to measure?

This study monitored the risk of what is referred to as “all-cause mortality” (death from any cause) during the 26 years that spanned 1991 – 2017 in Spain. The authors wanted to see if this risk was influenced by what people ate.

 

3) How was the study undertaken?

The study design described in this paper is called a longitudinal cohort survey. This simply means following the same group of people over a long period of time. Practically speaking, the authors gained access to a diet survey that was completed by 4679 individuals living in Spain in 1991. The survey is what is called a food frequency questionnaire and asked individuals to estimate over the previous 12 months how often they may or may not have eaten over 100 different foods.

Once the authors had this survey data, they classified the food items according to degree of “processing” as described by the NOVA classification.

The NOVA classification allocates foods into 1 of 4 groups depending on the level of processing the food has undergone. Group 1 for example are fruits and vegetables; Group 2 are culinary ingredients such as salts and oils; Group 3 are processed products with 3-4 ingredients while Group 4 are ultra-processed foods with multiple, highly refined ingredients and additives.

The authors then reviewed the National Institute of Statistics in Spain to see how many, if any, of these 4679 participants had died during the 26 years between completing the survey in 1991 and December 31, 2017.

Once they had both the diet and the incidence of death data, they used statistics to see if there was any increased risk of likelihood of dying in the 26-year period with the foods reported being eaten in 1991.

 

4) What did the study find?

The average age of individuals in the study was 30 years, and on average, this group of participants were eating about a quarter of their total daily energy from Group 4 ultra-processed foods products such as sugar sweetened beverages, milkshakes, meat and meat products like sausages and deli meats, dairy products, cakes pastries, sweets and cookies.

Of the 4679 individuals that completed the food frequency questionnaire in 1991, 450 had died by December 31, 2017.

And…. the higher the amount of Group 4 ultra-processed food products in the diet, the higher the risk of being one of those 450 individuals.

The actual risk reported by the study was a 15% increased likelihood of all-cause mortality for every 10% increase in the proportion of energy in the diet from group 4 products.

The authors also made some changes to the diet survey responses to see if the risk of all-cause mortality could be reduced and found that replacing Group 4 ultra-processed foods with Group 1 foods (fruits and veges) resulted in a statistically significant improvement and a reduced risk of all-cause mortality.

 

5) Is there any other research out there that supports these findings or contradicts it?

Absolutely, very similar studies have been completed on population data in France, the USA and Italy. Some of these studies have been completed in larger cohorts with the French study completed in over 100 000 individuals looking at cancer incidence in the first 8 years following diet survey. Each of these cohort studies are singing the same song – the higher the proportion of energy in your diet that comes from Group 4 ultra-processed food products. The higher the risk of health problems and disease.

To date, there are no studies that contradict this outcome.

 

6) How much weight should we give this research?

This study is interesting, and the statistical analysis is strong. Importantly it confirms data coming out of Europe and America that are generally telling us the same thing – the rise of ultra-processed foods is dangerous for our health. However, the sample size is relatively small, and there was only 1 diet survey completed in 1991 and how representative that was of each participant’s diet for the next 26 years is obviously a stretch.

 

7) What does this mean for your work/research/industry?

What this does for me is add strength to the need to continue to unpack the role of ultra-processed foods in the development of disease and empower individuals to make changes towards reducing the consumption of these foods.

 

8) What’s the key takeaway for us to take from this research?

If you can find the motivation and capacity to switch out an ultra-processed food product for its minimally processed equivalent – do it!

 

9) Will you be doing anything differently because of this research?

Not so much differently, but perhaps with more vigour, as it confirms the need for more current prospective studies in which we actively remove these group 4 foods from people’s diets and see if it improves their health as predicted.

 

Dr Kieron Rooney is a biochemist, nutritionist and exercise physiologist from the University of Sydney whose research focuses on how what we eat, influences our metabolism. 

 

Staying Healthy at Home

Many Australians are presently working from home. Cutting the travel time to and from work provide opportunities to spend that time doing other things we wouldn’t ordinarily have time for. But working at home can be a disruption to normal routines that we all tend to thrive on. One of the most common sentiments I hear as extended holidays draw to a close is that many actually look forward to having the routine that the work life brings. Lack of regularity is just one of several challenges being house bound presents us. With that in mind, I offer six suggestions to stay healthy and sane whist working from home for this next, unspecified period of time.

 

  1. Keep a regular sleep/wake schedule: Not having to wake up at a specific time to catch the bus to work and merely having to open the computer to start our day can allure us into creating haphazard sleeping schedules. Humans have evolved to keep regular sleep/wake, light/dark rhythms that rewards us with vitality, productivity and energy when we observe these regular sleep-wake cycles. This period of physical isolation allows us to firmly entrench an 8-hour sleep opportunity and circadian rhythm that we might never have again, as going out to restaurants and other entertainment is off the cards for the foreseeable future. Decide what time you would like to wake each day, work back 8-hours, allowing an extra 30 or so minutes for wind down, shower, intimacy and so on. Remembering to use bright lights in the morning hours and dim light in the period before bed. Then stick to this schedule every day. 

 

  1. Respect work/life balance: in our parents and grandparent’s day, for the vast majority, there were no mobile phones, computers and internet. Once the work day was done, adults did not go home and keep working until all hours.  Now that we are house bound and have access to emails on our phones, there can be a strong temptation to essentially work 7 days a week, without truly respecting down time. It would be wise to maintain ‘office hours’ and ‘personal hours’, where, during the latter, the phone and computer are off to work and on to family, friends and entertainment. 

 

  1. Set an exercise schedule: just as we have group exercise classes, personal training and running clubs, keeping a scheduled daily exercise regime (especially in the morning before work hours) is critical to maintaining momentum and not falling off the bandwagon during this time we are at home. Here are several suggestions:
  • Talking a 5 to 10-minute walk after meals aids blood sugar control and the energy slump we often get mid-afternoon. This is a very little time investment but has a huge potentially to make us feel great and energised;
  • Aim to walk in nature several times a week, so we don’t develop cabin fever from doing everything indoors.
  • Exercise every day and alternate hard (see next point) with easy sessions, such as walking and jogging;
  • Use time efficient modes of interval training, such as stair or hill runs, as the ‘hard’ sessions. Aim to accumulate at least 10 minutes of high-intensity work in these sessions. After a 5-minute warm-up, finding a hill or stairs it takes about a minute to reach the top, tackle these 10 times with a slow walk back down. Skipping is another tremendous exercise mode, where you would aim to do a similar workout (10 x 60-seconds of skipping with, say, 30-seconds rest in between);
  • Set up a body weight circuit three times a week. An example of a circuit might be: squats, push-ups, lunges, abdominal planks and skipping. Do each exercise for 60-seconds, moving quickly on to the next exercise. Rest a minute at the end of the circuit, and perform five rounds of the circuit, 

 

  1. Use house bound time wisely: This unusual time provides us with the perfect opportunity to work on aspects of health and fitness that we do no ordinarily have time for, such as stretching, trigger point work or foam rolling, deep breathing and meditation. It can be as simple as a 5-minute stretch, foam roll or deep breathing while you make your morning coffee or tea. It’s another healthy habit that takes basically no extra time from your day but doing it regularly will make you feel great.

 

  1. Be mindful of eating ‘as something to do’: Most people working from home have already worked this out – we eat because we are bored, procrastinating or as something to do. So that we all don’t gain unwanted weight over this time, it would be helpful to set an eating schedule that we stick to every day and avoid mindless walks into the kitchen to snack.

 

  1. Stay connected: It has already been observed that the phase ‘social distancing’ is unhelpful and the term ‘physical distancing’ might be more appropriate. We are very used to seeing people at work, on the bus or after work. This, for the time being, has largely stopped. Rather than just texting people, make the time during ‘personal hours’ try to use FaceTime, Skype and Zoom as a way of connecting with others, especially those really affected by isolation, such as the elderly. Try to call people as well, rather than texting. In this way, those who are more affected by physical distancing will feel a much greater sense of connection, which is far better for everyone’s mental health.

 

Dr Tony Boutagy is an Exercise Physiologist with a PhD in exercise and sports science from Charles Darwin University. He’s conducted over 50,000 training sessions in his career that has spanned 25 years, and is regarded as one of the premier personal trainers in the country. 

Expert Q&A: Introducing Dr Kieron Rooney

1) Could you tell us a little about your career and areas of expertise/interest? 

My day job entails conducting research and teaching on how what we eat, influences our metabolism. This work includes investigating for example, the influence of lower carbohydrate and higher fat diets in diabetes and obesity as well as on measures of performance in normal healthy individuals. I’ve also completed work on the role of high sugar diets in altering health status and the potential for non-nutritive sweeteners to assist recovery in diets focused on lowering sugar intake. I completed a PhD in Biochemistry in 2003 and since then have been an academic at the University of Sydney.

 

2) What drew you to this line of work/research in the first place? 

To be honest, it was the only thing I was good at at University. I squandered most of my first year enjoying the freedoms that University Student life brought. However, by second and third year I found myself intrigued by metabolic biochemistry and the way in which our entire system is integrated to utilise the energy of food we eat and how our behaviors may change to seek out specific foods. Through the course of my PhD and then academic life, the relationship between what we eat, how we eat it and our health fascinated me.

 

3) How do you look after your own physical and mental wellbeing?

I wax and wane. Periods of control and periods of laziness. I like to convince myself it is all by design. But to be honest sometimes I have all the energy in the world to commit to health and sometimes sleeping in, having an extra drink and getting take away feels like the right thing to do. When I am committed, there are 3 – 4, 7km runs a fortnight interspersed with some weights on alternate days and more often than not there are 10-11 home cooked dinners in that fortnight with leftovers for lunches. I typically avoid sugar sweetened beverages, and opt for extra veges over “passenger carbs” like bread and pasta 

 

4) Do you have a favourite post-workout cafe?

Not really, since most of my runs and weights workouts are at home. But if you are in the Balmain / Birchgrove area The Gladstone Corner store does a great long black.

 

5) What is one thing you wish people knew about wellbeing? 

It takes a conscious effort to find it, grow it and keep it. And a subconscious effort to lose it.

 

6) What is one of the most ridiculous things you’ve read or seen about wellbeing that you know to be untrue?

That you have to cut the fat off your meat to make it healthy.

 

7) Do you have any favourite books, podcasts or websites on health or wellbeing that you’d recommend?

I really enjoyed “the art and science of low carb living” and “The case against sugar” otherwise I am somewhat of an online itinerant.

 

8) What is your top tip for living a healthy and happy life? 

Every sugary drink is doing you harm

 

The Truth About Supplements

Supplements

Supplements are often the first question I get asked about.

The magic bullet that will improve your overall health and wellbeing in one or two (or sometimes 6) tablets a day! There are few, but critically important populations that do need supplements. For example, any woman of reproductive age is recommended to take a multivitamin every day to get sufficient folic acid. Folic acid supplementation reduces the chance of having a baby with neural tube defects. These defects occur very early during gestation, often before a woman knows she is pregnant. 

The main challenge in determining if they work or not is the one size fits all approach. There is A LOT of research done on supplementation. It is a multibillion-dollar industry that benefits from making health claims demonstrating the efficacy and or effectiveness of their products. 

If you think about all of the different supplements out there and all of the different health outcomes they purport to benefit, you are going to find some that have evidence to support their use. For example, if you look at the Cochrane Library Database* that houses the GOLD standard in reviews of the evidence for clinical studies and type in “probiotic” you will see that there are 56 reviews on them spanning topics such as “probiotics for treating eczema” to “probiotics for non‐alcoholic fatty liver disease and/or steatohepatitis”… And you will see there are over 7381 individual trials on them! 

So do they work? Maybe. It depends on what you are trying to measure. 

One of the biggest issues (and sometimes dangers) with recommending supplements is that there is an assumption that a particular naturally occurring vitamin or mineral in food, if taken in isolation and in high doses will lead to better health as we believe we understand the mechanisms by which it works.

Let’s take vitamin A or E as an example. These are antioxidants that combat free radicals. We assume vitamin A or E will reduce the damage to cells caused by free radicals, including damage to our DNA, which may play a role in the development of cancer. Seems logical these vitamins could help reduce cancer. Better load up on antioxidants supplements. 

Well they did just that back in the 1990s and early 2000s with a series of studies that were designed to improve cancer outcomes in high risk groups. 

One study conducted in the 1990’s wanted to test if the health effects of vitamins found in fruits and vegetables, retinol and beta carotene, (think vitamin A), which had been seen to be in higher concentrations in people with lower rates of lung cancer, would be the same when taken as a supplement. 

Over 18,000 men and women at a high risk of developing lung cancer were either assigned a beta-carotene and retinyl  palmitate (vitamin A) supplement taken daily or a placebo. The study was stopped ahead of schedule because participants who were randomly assigned to receive the beta-carotene and Vitamin A were found to have a 28% increase in incidence of lung cancer and a 17% increase in incidence of death compared to the placebo group. 

A second study in 2001 was conducted to determine the long-term effect of vitamin E and selenium on reducing the risk of prostate cancer in approximately 34,000 relatively healthy men >55 years. It was assumed these antioxidants would reduce the risk of cancers in high enough doses. 

Oral selenium and vitamin E was planned to be taken for a follow-up of a minimum of 7 and maximum of 12 years at very high doses. It was found that the risk of prostate cancers in men that were supplemented with vitamin E was 17% greater compared to a placebo (no supplement). In the selenium group there was also an increased risk but it wasn’t statistically significant.

So what does all of this mean?

Both of these studies highlight that caution should be used when recommending or using high doses of vitamins or micronutrients. Naturally occurring dietary constituents (i.e. vitamins and minerals) are part of normal physiology, and either deficiency or excessive doses are harmful. 

It doesn’t mean you shouldn’t adhere to advice given to you by your doctor or dietician if treating a medical condition, but it does show that the assumed benefit of a vitamin or mineral is not always correct when taken in isolation. 

This lack of benefit/potential harm from single antioxidants was later confirmed in 2012 with one of those GOLD standard Cochrane reviews I was talking about before that looked at Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

This review included 78 clinical trials with 296,707 participants randomised to antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. They found, wait for it, an increased risk of mortality was associated with beta-carotene and possibly vitamin E and vitamin A, but was not associated with the use of vitamin C or selenium, with absolutely no benefit of antioxidant supplements in the general population or in patients with various diseases.

Ok, but you are really here for me to tell you whether fish oil is good for you or not. Right? Well. 

A recent large Cochrane Review assessed the effects of increased intake of fish and plant-based omega-3 fats on all-cause mortality, cardiovascular events and blood lipids levels, mainly via capsules, as many people believe that taking omega-3 supplements reduces risk of heart disease, stroke and death. 

The review included 86 clinical trials and over 120,000 participants that compared greater omega-3 intake versus lower omega-3 intake for at least a year. The review found that increasing EPA and DHA (omega-3 fats found in fish) had little or no effect on all cause mortality, cardiovascular death, stroke, or heart irregularities.

So, what’s the take away from all this?

Some supplementation is necessary for some people

There will be new studies that may change what we know on some of the topics I have shared with you here, and if they do, and the reviews are high quality, without industry funding then the thinking around supplementation may change. But if you’re healthy, and not a female trying to fall pregnant or sexually active and of reproductive age, eat a minimally processed, plant-based diet and you are going to be in good health!

 

* Cochrane Library Database – If you ever want a summary of the evidence on a topic that uses randomized controlled trials to test an intervention, then this is the place to look – and they now give great plain language summaries.

 

​Dr Nick Chartres is the Director of Science & Policy at the University of California, San Francisco working with the Program of Reproductive Health and the Environment. His work focuses on US federal chemical policy and regulation.

Nick received his PhD from The University of Sydney, where his thesis examined ways to reduce bias in public health guidelines, including the primary studies that are used in our national Dietary Guidelines. Nick also has a Masters in Nutrition.

The Stages of Change

People know that smoking is bad for their health, but still choose to smoke. People know they ‘should’ go for that run, but still choose to sleep in. People know that the McDonalds drive through is not the healthiest option for dinner, but still use it on a Friday night after work. People are informed and educated around healthy behavioural choices, however still make unhealthy choices. Even when an individual has a serious health scare, they still may not want to change or know how to change the behaviours that have led them to their condition. 

The Transtheoretical Model (Stages of Change) can explain why. 

Social psychological research into dietary change and levels of physical activity are often the forgotten piece in understanding how to promote healthy behavioural change, long term. 

Health Behaviour Models

The contribution of social psychology is now becoming more and more influential in affecting long term dietary and exercise change. The most important contribution has been the advancement and application of various health behaviour models to initiate and promote change.

Some of the most popular models of health behaviour include: the health belief model; social cognitive theory; protection motivation theory; the theory of planned behaviour; and finally, and importantly, the transtheoretical model of change.

The Transtheoretical Model of Change (Stages of Change Model)

Developed by Prochaska and DiClemente, the model’s central concept is that all individuals pass through similar stages of change regardless of the problematic behaviour that they are trying to change.

These stages are:

  1. Pre-contemplation
  2. Contemplation
  3. Preparation
  4. Action
  5. Maintenance

With relapse common in the attempt to maintain any new behaviour.

Think of a current behaviour in your life that is potentially unhealthy. It doesn’t need to be anything too sinister; perhaps your partner has been telling you to drink less wine during the week, or you’re staying up past midnight binging on Netflix, or you’ve only exercised once in the past month. Look at each stage outlined below and see if you can identify which stage you are currently in, where you have been, and most importantly, where you would like to be!

Pre-contemplation: This is where a person has little to no awareness that their current behaviour is unhealthy or problematic. People in the pre-contemplation stage have no intention to change their behaviour in the foreseeable future. This is your husband or wife who you have desperately wanted to exercise for the past ten years, and despite your every attempt to change his or her behaviour, they haven’t even walked past the gym!! They’re thinking… “What problem?! It’s not a problem!”

Contemplation: This is where a person is thinking about making a change, but they haven’t yet taken any kind of action. This may have been you before joining the gym. People in contemplation see the advantages and disadvantages of their problematic behaviour… “I know that half a bottle of red wine each night isn’t great for my waist line, but it really helps me to relax once the kids have gone to bed.” Sound familiar?! 

Preparation: This is the third stage where a person shows intent to act and has gone about planning for changing their behaviour. This may have been you when you hired a personal trainer and started arranging for a regular time to be available in your week for exercise. 

Action: Once a person is engaging in their new healthy behaviour, they are in action. For example, doing your first exercise session!! This is also known as the “doing” stage.

Maintenance: Once a person has continued with their new behaviour for 6 months or more, they are in the final stage of change.  

Relapse: A relapse or a ‘lapse’ is a normal part of changing an unhealthy behaviour. A relapse is defined as going back to the problematic behaviour (or worse), whereas as a ‘lapse’ is like a little slip up. The important thing is to learn from any lapses or relapses by identifying the trigger, and then putting strategies in place for preventing another one from occurring in the future. 

As you pass through each identified stage of change, so too does your level of self-efficacy. In other words, once you progress to maintenance (especially if you have been following a detailed program) you will find it easier to identify and overcome any common barriers in the future. Therefore, when you relapse or lapse (which is very normal), you can re-implement your new learnt and healthful behaviours. The goal is to move towards maintenance, while increasing your levels of self-efficacy. 

It is important to note however, that ‘at-risk’ populations are often not prepared for the action stage and will not be served by traditional educational programs. Therefore, helping people set more realistic goals and assisting them in moving towards action with a trained professional is a very important step in this process. Professionals who have the right skills can guide you in changing your thinking and attitudes.

If you have issues with self-worth, or anxiety around changing your behaviour, or perhaps a belief that prevents you from acting, this is completely normal! Seeing a psychologist may be a crucial step for you in changing your problematic behaviour. Psychologists are well trained in dealing with ambivalence. It is very common for people to be ‘stuck’ in the contemplation stage. If this sounds like you, a psychologist can guide you in working through the pros and cons of changing your behaviour and collaborate with you to start preparing for change. 

Take Home Message

Changing life long behaviours and creating new healthy habits can be incredibly difficult. The first and most crucial step to the process is about identifying the behaviours in your life that are problematic. If you believe that you don’t have the ability to change, it is recommended that you seek professional help from a psychologist to guide you in commencing the process of change. Everybody can change a problematic behaviour; you may just have to change your attitude towards the behaviour first!

 

Simone Chartres is an endorsed Clinical Psychologist with the Australian Health Practitioner Regulation Agency (AHPRA). She has over 10 years of clinical experience working with young people and adults with complex presentations in the public and private sector. Simone has extensive clinical experience in the assessment, diagnosis and treatment of anxiety disorders, mood disorders, substance use disorders and eating disorders.

Research Review: Diets Rich in Fermented Foods Reduce Inflammation in our Bodies

In this article, our expert Dr Tony Boutagy – reviews Gut-microbiota-targeted diets modulate human immune status   by Wastyk et al. 2021, and breaks it down to give us the vital parts we need to know. 

1) What was the high-level summary of the research?

The microbial cells that live in the human gut are collectively called the gut microbiota or microbiome. These cell colonies significantly affect our metabolic and immune health and we know that diet plays a major driving factor in the composition and function of these microbiota.

This study found that a diet rich in fermented foods (things like sauerkraut, cottage cheese, kombucha, miso and kimchi)  enhances the diversity of these gut cells and decreases several markers of inflammation, which are linked to increased risk of chronic disease.

This is the first study to show that we can boost the diversity in these cells and lower certain markers of inflammation by eating a diet rich in fermented foods.

 

2) How was the study undertaken and what did it try to measure? 

This was a clinical trial of 36 healthy adults who were randomly assigned to a 10-week diet that included either fermented or high-fibre foods. The two diets were analysed to examine the potential for different effects on the gut microbiome and the immune system.

 

3) What did the study find? 

Over the course of the 10-week intervention, the researchers observed a decrease in many inflammatory markers in individuals consuming fermented foods and an increase in microbiota diversity. Eating foods such as yogurt, kefir, fermented cottage cheese, kimchi and other fermented vegetables, vegetable brine drinks, and kombucha tea led to an increase in overall microbial diversity, with stronger effects from larger servings

The results suggest that fermented foods may be powerful modulators of the human immune system and may provide an avenue to combat many diseases of modern civilization.

The findings also paint a nuanced picture of the influence of diet on gut microbes and immune status. On one hand, those who increased their consumption of fermented foods showed similar effects on their microbiome diversity and inflammatory markers, consistent with prior research showing that short-term changes in diet can rapidly alter the gut microbiome. On the other hand, the limited change in the microbiome within the high-fibre group supports previous reports of a general resilience of the human microbiome over short time periods, with the researchers speculating that changes in the microbiome may require more than 10-weeks in response to increasing dietary fibre intake.

 

4)  Is there any other research out there that supports these findings or contradicts it?

It has been known for some time that the microbiota is highly malleable and can be radically reshaped within days to months of certain events, such as when someone migrates to another country, takes antibiotics or changes their dietary habits. 

Previous research has demonstrated that humans living today in industrialised areas have reduced diversity in gut microbiota compared to our ancestors. Studies have also shown reduced diversity in these cells in modern industrialised communities compared to those eating a traditional, non-Western diet, without heavy food processing. 

This is the first study to demonstrate an increase in microbial diversity and lowered inflammation in response to a diet rich in fermented foods. The findings support previous reports that diet is an important modulator of the composition and function of the microbiome, and these changes can occur over a relatively brief period of time.

 

5) How much weight should we give this research?

This study was conducted by a multi-centre team of world leaders in both diet and the microbiome. They used state-of-the-art technologies to examine the composition of the microbiome and several markers of inflammation and found that high-fibre and high-fermented-food consumption influence the microbiome and human biology in distinct ways. While these findings are promising, they need to be further demonstrated in larger studies across diverse populations, 

However, given the fact that our present understanding of low microbiota diversity is associated with many chronic diseases of modern civilisation, such as obesity and diabetes, coupled with the knowledge that high levels of sanitation in industrialised populations has led to reduced microbial diversity, studies like this that show increases in microbial diversity by simply eating fermented food appear to be a simple and user friendly way to improve health.

 

6) What does this mean for your work/research/industry?

There is an immense body of literature that supports the role of fibre in health and lower rates of mortality. Studies also reveal the role dietary fibre plays in supporting gut microbiota diversity and metabolism and the positive role of short-chain fatty acids, a product of fibre fermentation by the gut microbiota, in maintaining gut barrier health and reducing inflammation

Dietary interventions that specifically alter dietary fibre, such as increasing total fibrous carbohydrates, whole grains, and resistant starch have shown impacts on the microbiota along with improvements in numerous health markers.

A recent study found differences in microbiota composition among fermented food consumers versus non-consumers. Given that fermented foods have historically been part of many diets around the world, consuming fermented foods may offer an effective way to reintroduce evolutionarily important interactions. They may also provide a way to rebuild microbes that have been lost over the course of the over sanitising of our modern environment.

Extensive data across the field of gut microbiome science has established that diet is a major driver of the species and functions that reside within an individual’s gut. Poor diet is a known contributor to many diseases of modern culture that are rapidly spreading globally as more populations adopt Western-style diets. Furthermore, many modern diseases are driven by chronic inflammation, an immunological state that is modulated by the gut microbiota.

 

7) What’s the key takeaway for us to take from this research?

This is the first study to demonstrate that eating a diet rich in fermented foods can both improve the diversity of the microbiota and reduce markers of inflammation. This increase in microbial diversity may play an important role in reducing the risk of developing several chronic diseases, such as type II diabetes and obesity.

 

8) Will you be doing anything differently because of this research? 

I have made a concerted effort to include fermented foods several times a day in both my and my family’s meals. These have included yoghurt, kefir, pickles, sauerkraut, kimchi and cottage cheese. I’m looking forward to exploring more food options that will bring in a greater variety of fermentation to our diets.

 

Tony Boutagy holds a PhD in exercise science, where his primary interest is in body composition and human performance. Dr. Boutagy shares his time between hands-on coaching in Sydney and online education on topics which include health, exercise and lifestyle.

Research Review: The Impact of Fruit and Vegetable Intake on Perceived Stress

In this article, our expert Dr Kate Edwards – Associate Professor in Exercise and Sport Science at the University of Sydney – reviews Fruit and vegetable intake is inversely associated with perceived stress across the adult lifespan by Radavelli-Bagatini et al. 2021, and breaks it down to give us the vital parts we need to know. 

1) What was the high-level summary of the research?

The study found that reported perceived stress levels were associated with fruit and vegetable intake in adult Australians, with those people eating the most fruit and vegetables (>473g/day) reporting lower perceived stress than those eating the least (≤243 g/day). The World Health Organisation recommends eating 400g/day of fruit and vegetables. When looking at the effect across the different age groups,  it was found that the positive associations were greatest in adults between the ages of ≥45-<65 years.

 

2) How was the study undertaken & what was it trying to measure? 

The data came from a large study, the Australian Diabetes, Obesity and Lifestyle (AusDiab) Study. AusDiab is a national population-based survey of Australian adults aged ≥25 years, recruited in 1999–2000 (AusDiab1), they also included data from the 5-year follow up in 2004-2005. This study included 8689 adults at baseline and 5031 at 5 years follow up.

 

3) What did the study find? 

First the study looked at the cross-sectional association (looking at the data at a single time point) and found that fruit and vegetable intake was associated with perceived stress. They then added into their model other factors that might also be associated with stress and that could attenuate the effects, like overall energy intake, physical activity, smoking, age, sex, BMI, relationship status, socio-economic index and chronic disease. Even accounting for all those factors, fruit and vegetable intake was still associated with perceived stress. Interestingly, when they looked at the change in fruit and vegetable intake over time, perceived stress was not associated, which the authors suggest means that fruit and vegetables might reduce perceived stress rather than stress leading to reduced fruit and vegetable intake.

 

4) Is there any other research out there that supports these findings or contradicts it? 

This data is similar in findings to other studies but is much more representative of the whole population. Prior studies have found similar associations in pregnant women and students and have included smaller numbers of people. The data is 20 years old, but Australian Bureau of Statistics suggests there has been little change in fruit and vegetable intake between 2007-2018.

 

5) What’s the key takeaway for us to take from this research?

Public health messaging about fruit and vegetable consumption might be well targeted to middle-aged adults, as the association between perceived stress and fruit and vegetable intake was strongest in that group, and if the effect can be confirmed the messaging of anti-stress effects could be powerful.

 

6) Will you be doing anything differently because of this research? 

This study suggests accounting for diet and in particular fruit and vegetable intake in stress research is important, and suggests that work examining the effect of diet interventions should be considered.

Expert Q&A: Introducing Dr Tony Boutagy

1) Could you tell us a little about your career and areas of expertise/interest? 

I started working in the fitness and health industry in 1995. Over the years I have worked in a number of related roles, but primarily as a trainer, strength coach and lecturer. My areas of interest are all things body composition, which covers nutrition, strength training, cardiovascular exercise and lifestyle.

 

2) What drew you to this line of work/research in the first place? 

I started work as a trainer while I was studying sports science at university, I immediately found the human body and the way it functioned incredibly fascinating, especially in its application to training and exercise, so my interest was captured and I’ve never looked back.

 

3) How do you look after your own physical and mental wellbeing?

I make exercise and sleep a non-negotiable priority. This means that most other things, other than family, are subordinate to the time I allocate to exercise and keeping regular sleep rhythms. I also cross train over the week, lifting weights, swimming, cycling, running and stretching. This keeps the stimulus and impact diverse and the exercise enjoyable.

 

4) Do you have a favourite post-workout cafe?

In Mosman, The Source Cafe in Raglan St and in the city, Mecca.

 

5) What is one thing you wish people knew about wellbeing? 

Small behaviours which become habits have profound impact on our health and well being. Sleeping 7-9 hours a night. Lifting weights and getting up a sweat with some intervals or a long run. This actions do not require a lot of time or motivation, but when done with consistency, improve our health in a remarkable way.

 

6) What is one of the most ridiculous things you’ve read or seen about wellbeing that you know to be untrue? 

Can I give three?

You can sleep less than 6 hours a night and be healthy.

Carbohydrates make you fat.

Strength training will make me bulky.

 

7) Do you have any favourite books, podcasts or websites on health or wellbeing that you’d recommend?

For a higher level discussion, Peter Attia’s podcast the Drive and Andrew Huberman‘s Lab are extremely good. For practical sports nutrition, I love From Paper to Podium. Matthew Walker’s book Why We Sleep is very good and Michael Hutchinson’s Endure is a great read on endurance exercise.

 

8) What is your top tip for living a healthy and happy life? 

Don’t spend time with boring people.

 

Expert Q&A: Introducing Dr Nick Chartres

1) Could you tell us a little about your career and areas of expertise/interest? 

I currently work in science policy in the United States. I work on environmental health research translation methods and the promotion of evidence-based federal policies to prevent exposures to harmful environmental chemicals.

A lot of my work is monitoring, evaluating and commenting on how the US Environmental Protection Agency regulates chemicals to ensure that they are consistent with the best scientific methods. Think of it like auditing. I look at whether an evaluation of a body of evidence examining a chemical, like asbestos, with a health outcome like cancer, is done accurately. I want to make sure there is no underestimation in the true risk posed by the chemical. This all sounds very esoteric, so why is this important? 

Adopting scientific methods that accurately capture risks is critical to protecting health, particularly for marginalised communities, such as fenceline (a neighbourhood that is immediately adjacent to a company and is directly affected by the noise, odours, chemical emissions, traffic, parking, and operations of the company. Historically, polluting facilities have often been built in or near African American communities) and communities of colour that can face the highest exposures to toxic chemicals and pollutants.

Currently, every year, there’s about 15,000 kgs of chemicals produced for every person in the U.S. and many of these chemicals are persistent and bioaccumulative (so they never break down and just keep piling up in our water, soil and air) and end up in people, who are vulnerable and disproportionately exposed. Our studies have found ubiquitous exposure of pregnant women to more than 43 different industrial chemicals, many with serious health hazards. Babies are born with chemicals in their bodies, and our studies have also found significant links between prenatal exposures and health harms to children like loss of IQ. Leukemia in children has increased by ~40% over the last few decades. I have children and this worries me deeply. 

My other key area of work is examining bias, both methodological and financial conflicts of interest, in research. We know that in multiple areas of research that the presence of industry sponsorship leads to more favourable study outcomes towards the study sponsor, than those without industry sponsorship. So again, why is this important? Well, if the study results we use in things like the dietary guidelines are biased due to food industry sponsorship, then the recommendations that are made may not be valid. So I study this and work on strategies to try minimise its influence in research. I conducted the first in-depth study examining the association between industry sponsorship with the outcomes of primary nutrition research. 

 

2) What drew you to this line of work/research in the first place? 

I have a really deep interest in public health. I have had a privileged life and upbringing so I’m particularly interested in protecting marginalised communities that don’t have access to the same level of health I do. The corporate strategies that industries use to sell products that are harmful to the public’s health, like processed foods, tobacco, chemicals, fossil fuels and alcohol all disproportionately impact low income, indigenous and communities of colour. The products these industries produce are causing the global increase in non communicable diseases and death. The Global Burden of Disease estimates that approximately a third of deaths worldwide are attributable to behavioural risk factors that, at their core, have the consumption of unhealthful products and exposures produced by profit driven commercial entities.

A basic human right is that everyone’s children can grow up in a world that is toxic free, with access to a healthy food system. Unfortunately for 90% of the world that isn’t the case. So I’m interested in trying to make it more equitable. 

 

3) How do you look after your own physical and mental wellbeing?

The $64,000 Question… I’ve always had a pretty good relationship with food and exercise. If I don’t do something physical every morning before work my brain doesn’t work. I’ve always loved meat but as I have gotten older, the more plants I eat, the better I feel. I want to sleep more because that’s when I’m happiest and smartest but it’s not always possible. I try to play with my kids everyday, I’m not good at mindfulness but they make me mindful. I love drinking beer after work on a Thursday (the new Friday since having kids) or Friday night. 

 

4) Do you have a favourite post-workout cafe?

Ha. Yes, my kitchen. I exercise in my garage or go for a run from home so this is where I end up. In San Francisco there’s one place I get a coffee sometimes on a Saturday morning called the Roastery, which is super cool and old school. It has these huge hessian bags of the different coffee beans in the shop, so when you walk in the smell just smacks you. Magic.

 

5) What is one thing you wish people knew about wellbeing? 

That human connection and relationships are the most important thing to a healthy life (although I’m sure many people know this). I think being part of a community, contributing to that community and staying active is critical to anyone’s wellbeing. That’s a partly scientific answer and part anecdotal. Also just eat as many plants as you can. Buy a good recipe book and learn how to make them tasty for you and your kids. You will live much longer if you do.

 

6) What is one of the most ridiculous things you’ve read or seen about wellbeing that you know to be untrue? 

Ha. Other than the Ab Cruncher 2000 (I made that name up but you get the idea) that could melt stomach fat away in only 6 minutes a day! I see bad science everyday in my work. Going back to my work in nutrition I think the most ridiculous thing is that a lot of the food industry, especially Coca Cola have tried to frame the obesity epidemic around a lack of exercise as being the main determinant and not their highly processed food commodities.

They’ve spent a lot of money on funding research, researchers and developing marketing campaigns to confuse the public and persuade policy makers. If we removed highly processed food commodities from our food systems, or regulated their production, we would significantly reduce the number of people that die from diseases related to obesity. The economic impact and thus relief on our health care spending would be astronomical.

 

7) Do you have any favourite books, podcasts or websites on health or wellbeing that you’d recommend?

Marion Nestle Food Politics

Gyorgy Scrinis Nutritionism

Good Mood Dudes Podcast

 

8) What is your top tip for living a healthy and happy life? 

Probably the same as number 5. Being connected with a community and having a purpose (maybe that’s a little too existential for this question!). And eating lots of fruits and vegetables everyday.

 

See some of Nick’s published research here.