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Family upbringing has no impact on adolescents’ food preferences

By Alison Fildes, on 11 July 2016

Written by Andrea Smith, Alison Fildes and Clare Llewellyn

Understanding the factors behind food likes and dislikes has important implications for politicians and clinicians. Our food preferences strongly influence what we chose to eat, affecting our health in the short- and long-term. Previous studies carried out by our group have shown that aspects of the shared family environment played an important role in shaping young children’s food preferences.  However, the relative influences of genes and the environment on older teenagers’ preferences was previously unknown.

In a new study published this week in the American Journal of Clinical Nutrition we explored the relative importance of genetic and environmental influences on adolescents’ food preferences using a twin design. The findings revealed that the effects of family upbringing on teenagers’ food preferences seem to disappear as they start to make their own meal choices, to the point where they have no detectable impact by late adolescence. Instead the ‘unique environment’ – aspects of the environment that are not shared by both twins in a pair (e.g. experiences  unique to each twin, such as having different friends) were found to effect food likes and dislikes at this age. Genes were also found to have a moderate impact on food preferences in late adolescence, in keeping with earlier findings from young children.

The research involved 2,865 twins aged 18-19 years from the Twins Early Development Study (TEDS), a large population based cohort of British twins born in 1994 to 1996. Food preferences were measured using a self-report questionnaire of 62 individual foods which were categorised into six food groups – fruits, vegetables, meat/fish, dairy, starch food and snacks. It is the first study to show how substantial influences of the shared family environment in early childhood are replaced by environmental influences unique to each individual by the time they enter young adulthood. The decreasing influence of the family environment in adolescence has also been observed for other traits, such as body weight.

The results of this study mean that efforts to improve adolescent nutrition may be best targeted at the wider environment rather than the home, with strategies focused on increasing the availability and lowering the cost of ‘healthier foods’. The substantial influence of the non-shared environment, suggests that food preferences can be successfully shifted towards more healthy choices in late adolescence. Policies that make the healthier food choice, the easier choice for everyone, have potential to achieve substantial public health improvements. In particular, the UK sugar-sweetened beverage levy soon to be introduced is one initiative that has the potential to promote a healthy food and drink environment.

 

Article link:

Smith AD, Fildes A, Cooke L, Herle M, Shakeshaft N, Plomin R, and Llewellyn C. Genetic and environmental influences on food preferences in adolescence. American Journal of Clinical Nutrition. First published ahead of print July 6, 2016. doi:10.3945/ajcn.116.133983

http://ajcn.nutrition.org/content/early/2016/07/05/ajcn.116.133983.full.pdf+html

Measuring appetitive traits in adults. What do we know about their relationships to weight.

By rmjlhun, on 6 July 2016

By Claudia Hunot, Alison Fildes and Rebecca Beeken.
Some people are more likely to put on weight than others, and may find it harder to lose weight. One of the ways in which people differ is in how they respond to food; their ‘appetitive traits’. For example, how full you tend to feel after a meal, how much you want to eat when you see or smell delicious foods, or how fast you eat. These traits are partly influenced by genes, and they explain individual differences in the way we all eat. In the present-day food-filled environment people who are more responsive to food cues (want to eat when they see or smell delicious food), and less sensitive to satiety (take longer to feel full) are more susceptible to over-eat and gain weight.

For a number of years, appetitive traits have been measured in children using the ‘Child Eating Behaviour Questionnaire’ (CEBQ) and more recently in infancy using the ‘Baby Eating Behaviour Questionnaire’ (BEBQ). These questionnaires measure a number of appetitive traits that can be grouped into two broad categories: food approach and food avoidance traits. Food approach traits, such as ‘food responsiveness’, are associated with a larger appetite or greater interest in food, while food avoidance traits such as ‘satiety responsiveness’ are associated with a smaller appetite and/or a lower interest in food. Research has shown higher scores on food approach traits and lower scores on food avoidance traits are associated with increased weight and weight gain. However, so far most of this research has been carried out in children. Until now no matched questionnaire existed for measuring the same appetitive traits in adults.

Therefore, in our latest study we developed the ‘Adult Eating Behaviour Questionnaire’ (AEBQ) to measure these appetitive traits in adults. We also wanted to explore whether these traits relate to adult weight, as they do in children. Adult samples were recruited at two time points, one-year apart, from an on-line survey panel. Participants completed the AEBQ and provided their weight and height measurements to calculate BMI. Data from a total of 1662 adults was analysed and showed the 35 item AEBQ to be a reliable questionnaire measuring 8 appetitive traits similar to the CEBQ.

We also showed that food approach traits such as ‘food responsiveness’, ‘emotional over-eating’ and ‘enjoyment of food’ were positively associated with BMI. This means people with higher scores for these traits were heavier on average. While food avoidance traits including ‘satiety responsiveness’, ‘emotional under-eating’ and ‘slowness in eating’ were negatively associated with BMI. This means people with higher scores for these traits were lighter on average.

These findings suggest appetitive traits are likely to be important for weight across the life course. The newly developed AEBQ is a reliable instrument, which together with the BEBQ and the CEBQ, could be used to track weight-related appetitive traits from infancy into adulthood. The AEBQ may also help to identify individuals at risk of weight gain and could inform targeted interventions tailored to help people manage their appetitive traits, and in turn control their weight.

Article link:
Hunot, C., Fildes, A., Croker, H., Llewellyn, C. H., Wardle, J., & Beeken, R. J. (2016). Appetitive traits and relationships with BMI in adults: Development of the Adult Eating Behaviour Questionnaire. Appetite. http://dx.doi.org/10.1016/j.appet.2016.05.024
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Updating the General Nutrition Knowledge Questionnaire for adults

By rmjlkli, on 17 June 2016

By Nathalie Kliemann, Fiona Johnson and Helen Croker

Access to nutrition information is widespread and many people rely on sources such as newspapers, websites, magazines, and TV programmes. Some of the information is conflicting and misleading, and the sheer quantity can be overwhelming, leaving many people confused as to what is the current nutrition advice. In an attempt to understand how well UK adults understand nutrition information, in the 1990’s researchers at the Health Behaviour Research Centre developed a questionnaire to assess general nutrition knowledge (GNKQ) in the UK adult population. This measure has been widely used since then and is cited in over than 150 research papers, which have explored the relationship between nutrition knowledge and other factors, such as dietary intake, socio-economic status, and use of food labels. It has also been adapted for use in different populations and translated into other languages, including Turkish, Romanian, and Portuguese.

Why update it?

Since the GNKQ was developed 20 years ago,  there have been developments in our understanding of the links between diet and health, and big changes in the food supply including the introduction of new types of foods and processing methods. This has resulted in new advice regarding good nutrition, and the GNKQ needed updating to reflect the way we eat today and bring it into line with current recommendations. Our recent publication reported the development of a revised GNKQ, with four main sections measuring: knowledge of dietary recommendations; food groups; healthy food choices, and links between diet and ill health. We also conducted 4 studies to test how well the questionnaire measures nutrition knowledge in adults (tests of reliability and validity).

Main results

Our findings showed that the revised version of the GNKQ is a consistent, reliable and valid measure of nutrition knowledge, and that scores improve when people undertake nutrition training. It also showed some differences between people, as the GNKQ-R scores were higher among women, people with a degree, those with better health status and in younger adults. The sections can be administered individually to measure specific areas of nutrition knowledge. We concluded that the revised version of the GNKQ will be a useful tool to assess nutrition knowledge among the UK adult population, and identify groups of people who might benefit from nutrition education to navigate their way through the mass of nutrition information available.

Article link:

Kliemann N, Wardle J, Johnson F & Croker H. Reliability and validity of a revised version of the General Nutrition Knowledge Questionnaire. European Journal of Clinical Nutrition, 2016, 1-7.

www.nature.com/ejcn/journal/vaop/ncurrent/pdf/ejcn201687a.pdf

 

Learning to like vegetables: Starting early

By Alison Fildes, on 10 June 2015

Vegetables are commonly among children’s least liked foods, while sweet-tastes are preferred from the outset. These preferences are reflected in children’s diets with children in the UK and other European countries eating too few vegetables and too many sugary foods. Evidence suggests introducing vegetables early in life may have important implications for future health. It is possible to learn to like foods, such as vegetables, simply by trying them on multiple occasions. Older children (or adults) may need to try a food 14 times or more before they begin to like it but infants are particularly accepting of new tastes. This makes the weaning stage is a key period for learning to like a variety of different foods.

As part of the European HabEat project we conducted an exploratory trial investigating the impact of advising parents to introduce of a variety of single vegetables at the very start of weaning. Pregnant women or mothers with infants less than 6 months old were recruited from healthcare settings in the UK, Greece and Portugal. Mothers and their infants were randomized (allocated by chance) to either an intervention group or a control group, ensuring there were equal numbers of breast-fed and formula-fed infants in each group. Intervention mothers were visited before they started weaning and were given advice on introducing five vegetables (one per day) as their baby’s first foods, repeated over 15 days. After the first 15 days, intervention mothers were told to continue to offer vegetables but also to start introducing other age-appropriate foods such as fruit. Mothers in the control group received standard care, which varied from country to country. For example, UK recommendations are to introduce fruits, vegetables and baby rice or cereal as first foods, but the information provided to mothers is inconsistent and access to advice may vary by region.

Taste tests were conducted one month after the start of weaning. Intervention and control infants were fed unfamiliar vegetable (artichoke) and fruit (peach) purées and a researcher recorded how much of it they ate (g) and how much they appeared to enjoy these foods. When the results for the UK, Greece and Portugal were combined (n=139) the children who took part in the intervention, and ate a variety of vegetables for the first 15 days of weaning, had not eaten significantly more of the unfamiliar vegetable purée than the children from the control group. However in the UK, intervention children ate almost twice as much of the unfamiliar vegetable compared with control children whose parents were not advised to offer vegetables as first foods (32.8g vs. 16.5g). UK mothers and researchers also rated intervention infants’ as liking the vegetable more. Whereas in Portugal and Greece there was no significant effect of the intervention on infants’ intake of or liking for the vegetable. In all three countries, there was no difference between groups in the amount of fruit purée children ate or how much they seemed to like it.

These results may be partly explained by variation in existing weaning practices across Europe. Common first foods given to UK infants include fruits and ‘baby rice’. Vegetables, particularly green or bitter tasting varieties, are offered less frequently. When they are introduced vegetable purées are often combined with fruits such as apple or pear, sweetening the food and potentially masking the vegetable flavour. In contrast vegetables are regularly offered as first foods in Portugal where vegetable soups are a common weaning food. These differences may be reflected in later dietary patterns as Portuguese school-children have some of the highest levels of vegetable intake in Europe.

The findings of this study suggest that repeatedly offering a variety of vegetables to infants at the start of weaning may work to increase vegetable acceptance in countries where vegetables are not already given as first foods. However, we don’t know yet whether this effect will last throughout toddlerhood and into later childhood, so this will need to be explored in future studies.

Reference: Fildes A., Lopes C., Moreira P., Moschonis G., Oliveira A., Mavrogianni C., Manios Y., Beeken R., Wardle J. & Cooke L. (2015). An exploratory trial of parental advice for increasing vegetable acceptance in infancy. British Journal of Nutrition. journals.cambridge.org/bjn/vegetabletrial

To achieve weight loss, fat shaming is not the answer

By Susanne F Meisel, on 11 September 2014

Negative attitudes towards obese individuals therefore remain one of the ‘last socially acceptable forms of prejudice’ . One has only to glance at the ‘comments’ section of media reports discussing obesity to realise that obese people are openly subjected to labelling and stereotyping, and some outright abusive attacks. Unfortunately, stereotypes of the overweight and obese are held across all segments of society, including those working in health and social care .

Despite solid evidence (and frequent discussion on this blog) showing conclusively that whole host of factors contribute to excessive weight gain,currently, responsibility for maintaining a healthy weight rests solely with the individual. Therefore, people may think that stigmatising those who ‘refuse’ to conform to the ‘societal imperative’ is justified . Some may go even further and claim that stigmatising overweight and obese people would encourage them to lose weight. However, when our researchers looked at the scientific literature surrounding stigma and weight loss, there was little evidence showing whether this was actually true.

To find out whether weight and the experience of stigma are related in some way, researchers from our department looked at data from 2,944 UK adults over four years who participated in the English Longitudinal Study of Ageing (ELSA), a study of adults aged 50 or older. Participants are weighed and measured every four years, and asked questions on a range of topics every two years.

To assess stigma, participants were asked how often they encounter five discriminatory situations: ‘In your day-to-day life, how often have any of the following things happened to you: 1) You are treated with less respect or courtesy; 2) you receive poorer service than other people in restaurants and stores; 3) people act as if they think you are not clever; 4) you are threatened or harassed; 5) you receive poorer service or treatment than other people from doctors or hospitals. Responses ranged from ‘never’ to ‘almost every day’. Participants who reported discrimination in any of the situations were asked to indicate the reason(s) they attributed their experience to from a list of options including weight, age, gender, and race. The researchers considered participants who attributed experiences of discrimination to their weight as cases of perceived weight discrimination. Because many participants reported never experiencing discrimination, the researchers divided responses to indicate whether or not respondents had ever experienced discrimination in any domain (never vs. all other options).

Of the 2,944 eligible participants in the study, 5% reported weight discrimination. This ranged from less than 1% of those in the ‘normal weight’ category to 36% of those classified as ‘‘morbidly obese’. Men and women reported similar levels of weight discrimination.

However, those who reported experiencing weight discrimination gained more weight than those who did not over the 4-year period. On average, after taking baseline differences in BMI, gender, age and personal wealth into account, people who reported weight discrimination gained 0.95kg whereas those who did not lost 0.71kg, a difference of 1.66kg.

However, because this study looked only at the relationship of perceived stigma and weight gain, we cannot conclude that stigma caused weight gain – it could also be that weight gain increased perceived stigma, or that a third factor influenced both weight gain and stigma. To conclusively establish whether stigma indeed causes weight gain, we would have to run a controlled experiment with at least two groups of similarly overweight people, where one group is subjected to stigma over a period of time, and the other one is not, and then measure their weight at the end of the study. Of course, such an experiment would be highly unethical, given the damaging effects of stigma on psychological health. Another limitation of this study was that discrimination was assessed two years after the initial weight measurements and two years before the final measurements, although the researchers controlled statistically for this.

However, regardless of its limitations, this study showed that weight discrimination is definitely not associated with weight loss. This means that there was no evidence for the idea that stigmatising overweight and obese individuals would motivate them to lose weight. in many cases, it may even hinder weight loss. Therefore, we should work towards removing prejudice and blame from weight loss advice and should focus on positively supporting those who are trying to lose weight. One way may be to teach active coping strategies and increasing acceptance-based elements into weight loss programmes because this has had some promising effects. Furthermore, we will need to continue highlighting the complex causes of obesity rather than relying on simplistic representations, and increase work to acknowledge and address weight-related stigma, to make the ‘last socially acceptable form of prejudice’ unacceptable.

 

Article link:

Jackson, S. E., Beeken, R. J., & Wardle, J. (2014). Perceived weight discrimination and changes in weight, waist circumference, and weight status. Obesity, n/a.  http://onlinelibrary.wiley.com/doi/10.1002/oby.20891/full

 

The darker side of weight loss – why it is important to pay attention to mood changes when losing weight

By Susanne F Meisel, on 7 August 2014

The increasing prevalence of weight-related diseases have led health organisations world-wide to advise overweight and obese people to lose weight.  Indeed, the notion that weight loss is generally ‘a Good Thing’ for people who are overweight (BMI 25-30) or obese (BMI ≥30) seems to have been taken on board by the wider society.  Rightly or wrongly, magazines are full of stories, tips and tricks on how to achieve the ‘perfect’ weight, and the diet industry’s worth is estimated to be several billion pounds.   In a recent study of over 9000 overweight and obese adults, over 60% reported that they were ‘trying to lose weight’.

Undoubtedly, even losing relatively small amounts of weight (5% of body weight) will reduce the risk of many obesity-related conditions and diseases, most notably, diabetes, heart disease and stroke.  There are also many reports that weight loss has psychological benefits.  Most commonly, people said that they had improved energy levels, and felt less depressed after losing weight.

However, when researchers from our department looked more closely at the evidence for improvements in depression, it became clear that most of these reports came from people in weight loss trials.  Interestingly, mood improvements often occurred before any weight was lost in these studies, and were not related to the actual amount of weight lost.  This suggests that factors other than weight loss per se may have been responsible for the reported mood improvements.  One explanation is that personal contact (which is a central part of most weight loss trials) may have been responsible for people feeling less depressed by providing support during the weight loss process.  Furthermore, it is likely that people who take part in weight loss trials are very different from the ‘average’ weight loser in the population, so we cannot say that findings from trials will also be true for most people in the UK.

When our researchers looked for studies that used big samples that were representative of the population, they found results from only two studies, the Health and Retirement study, and the Health ABC study.  Curiously, both of these reported slight increases in depressive symptoms in people who lost weight.  However, because these studies also included healthy weight people, and did not look at whether people wanted to lose weight, or lost weight because they got ill during the study period or had significant stress in their lives (which is often related to both weight loss and depression) it was difficult to determine what the reason behind this puzzling finding was.

Therefore, our researchers set out to explore the relationship between weight loss and depressed mood in the English Longitudinal Study of Ageing (ELSA), a large cohort, representative of the UK population that has been going on for over 12 years.  The good thing about ELSA is that it includes lots of measures on all sorts of topics, so that it is very unlikely that people take part because they feel strongly about a certain issue, and it weighs and measures all of its participants every four years so does not rely on self-reported data.

For this particular analysis, the researchers decided to only look at overweight and obese people because these are the people who might be advised to lose weight; a sample of 1979 people.  They also used data telling them about participants’ intention to lose weight, their mood (using an established scale for depressive symptoms), any life stressors or illnesses that occurred during the study period, and blood pressure and triglyceride levels (which were used to check that people benefitted physically from weight loss in the expected way).

The results showed that people derived typical physical benefits from weight loss, with blood pressure and blood test results improving over a period of four years.  However, just like in the other two studies, our researchers found that overweight and obese people who lost at least 5% of their body weight (which is recommended) over four years were nearly twice as likely to be depressed than people who were weight stable, even when taking life stress and onset of illness into account.

However, this study was not able to determine cause and effect, so it is impossible to say whether weight loss caused depressed mood, or whether depressed mood caused weight loss or a third factor that was not measured caused both weight loss and depression.  It is important to investigate these findings further in order to establish why these results were observed, and why they differ so greatly from those reported in weight loss trials; especially since there are so few other studies out there at the moment that could hint at an explanation.

People often think that losing weight will make them happier, but these findings suggest that weight loss may not always be a positive experience.  In fact, the psychological ‘costs’ of weight loss might explain why many who do successfully lose weight struggle to keep the weight off in the long term.  However, this is not to say that people should not attempt to lose weight – after all, people in the study got physically healthier.  Rather, it seems important that service providers are mindful of the possibility that weight loss may worsen mood, and to perhaps include an assessment of mood in their weight loss programmes.  It may also be sensible for anyone trying to lose weight to be aware of any on-going mood changes and to seek psychological support from health professionals or even friends and family if they begin to struggle.

Article reference:

Psychological Changes following Weight Loss in Overweight and Obese Adults: A Prospective Cohort Study

Jackson SE, Steptoe A, Beeken RJ, Kivimaki M, Wardle J (2014) Psychological Changes following Weight Loss in Overweight and Obese Adults: A Prospective Cohort Study. PLoS ONE 9(8): e104552. doi: 10.1371/journal.pone.0104552

Letting your imagination run wild – genetic testing for risk of weight gain

By Susanne F Meisel, on 5 April 2013

These are exciting times for people working in genetics.  The field has become trendy.  ‘DNA’, ‘genes’ and ‘genetic code’ are no longer specialist terms, but used casually in everyday language. The media love ‘The gene for’ stories  and attributing individual differences to biology and less to environment is becoming commonplace.  I recently read an interview with a singer who explained that she could not imagine being anything else but a singer, because singing ‘was in her DNA’. If this still does not convince you: The pop band ‘Little Mix’ recently released a new song titled ‘DNA’ (http://www.youtube.com/watch?v=D3h-lLj3xv4).

Why the fascination with genes?  To a degree, it appears to stem from the inherent assumption that our genes can give us insights into ourselves that would otherwise remain inaccessible. Although our DNA is  99.9% identical, this is not interesting – it is all about the tiny bit of difference, the bit which sets us apart and makes us unique.

Companies have been quick to capitalise on our curiosity of what would be possible once the Human Genome was decoded.  Genetic tests for an array of traits and conditions, including those that are common and driven by lifestyle, such as obesity or heart disease, are already available over the Internet.  So far, we are not sure about the effects of giving this type of information to people. It could be that people will use it to prevent the condition. Alternatively, it could be that they become fatalistic or complacent. I have written in more detail about the current debate in a previous blogpost ( http://tinyurl.com/bve6y2m).  I hope to add some evidence to the debate by looking at the psychological and behavioural consequences of receiving genetic test feedback using obesity as an example for a very common, very complex condition.

Because we do not know yet how people react to knowing about their genetic susceptibility to weight gain, it would be unwise to give them this information right away.  Instead, we set up an online study where people were asked to imagine their reactions to receiving a ‘higher-risk’ or an ‘average-risk’ genetic test result for weight gain. They were then asked questions on a broad range of feelings and behaviours. We included 2 sets of people, nearly 400 students, who were predominantly of healthy weight and almost as many people from the general public who were or had been overweight.

Results showed that people in both groups reported to be more motivated to make lifestyle changes after imagining getting a ‘higher’ genetic risk result than after imagining getting an ‘average’ genetic risk result. On average, negative feelings and feelings of fatalism were anticipated to be very low and did not differ between risk scenarios. Those who were already overweight or obese were more likely to think that in comparison with an ‘average’ genetic risk result, receiving a ‘higher’ genetic risk result would offer them an explanation for their weight status.  Finally, people in both groups thought that they would be more likely to seek out information about what their result means in the ‘higher-risk’ than in the ‘average-risk’ scenario.

These findings are good news, because they suggest that giving people feedback for susceptibility to weight gain is unlikely to have unanticipated negative effects, and may even be motivating.  Furthermore, people who are already overweight may also benefit from genetic feedback.  However, these findings may not hold up once people are actually given genetic test feedback, because they only tell us about what people think they might do – and people find it generally quite difficult to imagine to be negatively affected by an event.  The next step is now to give people ‘real’ genetic feedback for risk of weight gain to discover the effect of this type of information.

 

Reference:

Meisel, S. F., Walker, C., & Wardle, J. (2011). Psychological Responses to Genetic Testing for Weight Gain: A Vignette Study. Obesity (Silver Spring); 20 (3).DOI: 10.1038/oby.2011.324

 

Log it to lose it

By Susanne F Meisel, on 26 September 2011

How self-monitoring tools and participation in online support groups assists weight loss

 

The internet can be a wonderful place, with hours of fun to be had looking at unlimited amounts trivial information, bad adverts and cats doing the craziest things. However, new research by our research group suggests that the Web may have benefits for those looking to shed the pounds and stay fit, too.

Dr Fiona Johnson and colleagues used data collected from a commercial online weight-loss programme (Nutracheck) to see if individuals monitoring their diet and exercise levels using the software more regularly were more likely to lose weight.  The programme is an online platform which helps users track diet and exercise goals in addition to providing weight charting software, information about nutrition and health and an online forum. With over 3500 subscribers’ data to look at, there was enough information to see which techniques worked best and for whom. What the researchers wanted to find out was whether men and women used the programme differently, and whether any particular parts were more effective than others for losing weight.

The main finding was largely unsurprising – the more often people logged into the programme the more weight they lost, demonstrating the benefits of encouraging users to return frequently to online weight loss programmes.  There were also differences between the genders. Using online support forums was a better route to weight loss for women, whereas recording exercise levels seemed to increase success in men. Looking a little deeper in the data reveals yet more interesting patterns. Overweight or obese men and women that used food diaries the most were substantially more likely to lose over 5 % of their body weight (an amount which is likely to have health benefits) than those who logged their food consumption less diligently. Overweight and obese men seemed to benefit particularly from exercise diaries, with the most engaged being the most likely to shed significant amounts of weight.

We all knew it – consistency is the key. Just sticking to actually using the programme you spent your precious money on will help fight the flab. If you are a man, making note of how often and how long you spend exercising and toning your Adonis body appears to be the route to success. And if you are a woman, chatting about the experience of weight loss and dieting will help even more. So what are you waiting for? Stop looking at crazy cats and get logging!

 

Reference:

Johnson, F & Wardle, J. (2011) The association between weight loss and engagement with a web-based food and exercise diary in a commercial weight loss programme: A retrospective analysis. International Journal of Behavioural Nutrition and Physical Activity. 8:83 doi:101186/1479-5868-8-83

 

Susie (susanne.meisel.09@ucl.ac.uk)