As Hippocrates, the father of modern medicine, said more than 2,000 years ago, ‘All disease begins in the gut’. And modern science is proving it as true today as it was then.
In this blog we outline the importance of gut microbiota and the use of diet to affect them to try to improve health and welfare.
For a detailed exploration of the topic, register for our free, CPD-accredited NutriWebinar. Led by experts Professor Glenn Gibson and Laura Tilt, it will give you both incredible insight into the science and practical tips on how to help balance gut microbiota for real health benefits.
The importance of the gut microbiome
We have more than 1,000 species of bacteria in our gut. And there’s been an increasing realisation among scientists that these can have a profound effect on our health – from Irritable Bowel Syndrome to infections, asthma and inflammatory disease right through to bone health and cognitive function.
This understanding has led researchers to investigate what we can do to affect the microbiota, to be applied to this wide range of health problems. A steady stream of scientific publications over the last 15 years address the topic, alongside research into probiotics and, more recently, prebiotics – which selectively fertilise the ‘good’ bacteria.
Our gut microbiome status changes throughout our lives. We acquire our gut bacteria mostly at birth. Moving through the milk years, there are differences in acquiring bacteria between breast-fed and infant formulae fed babies: human milk.
There is change again at the weaning stage, after which the gut microbiota remains fairly stable. As we get older there is then a decrease in the largely in beneficial bacteria like the bifidobacteria.
The gut microbiota can be susceptible to various challenges: stress, infection, antibiotics and poor diet all amongst the factor coming into play on a daily basis.
How does diet affect our gut microbiome and our health?
Carbohydrates, proteins, amino acids and lipids are all metabolised by microbiomes in different ways, with different outcomes for our health.
Carbohydrate metabolism – especially that of fibre – leads to organic acids, short chain fatty acids, that have shown to be beneficial in the gut. For example:
- Acetate is metabolised by the muscle, kidney, heart and brain
- Propionate, cleared by the liver, is an appetite regulator also said to be involved in cholesterol synthesis
- Butyrate is a fuel and regulates cell growth
Fibre itself can stimulate the growth of good bacteria. It’s been estimated that per 100g fibre fermented, 30g of bacteria is produced.
Metabolism of excess protein, on the other hand, leads to less positive end products:
- Ammonia induces quick cell turnover
- Phenols/indoles may act as co-carcinogens
- Amines are linked to migraine, cancer, schizophrenia
Balancing our gut microbiota
- Increased fibre intake
To help ensure balanced gut microbiota, our diet needs to include enough fibre. As discussed in our recent blog, government recommendations advise 30g per day for adults, representing a 60% increase in intake for most. Laura Tilt provides excellent advice on how this can be achieved in the NutriWebinar.
- Probiotic and prebiotics
Much work has been done into probiotic supplements: live ‘good’ bacteria that bring health benefits, especially lactobacilli and bifido bacteria.
More recently, scientists have found that prebiotics could have an even more profound effect on our health. They work by selectively proliferating beneficial bacteria, which in turn inhibit pathogens. They may also have a more general effect, including dampening inflammatory issues.
Prebiotics are found naturally in human breast milk and in fructans and inulins in vegetables including asparagus, onion, banana and leeks. They can also be taken as supplements, especially in GOS forms.
As our understanding of the link between gut microbiota and our health has grown, researchers have increasingly looked to see where we can have the most impact.
We’re in a position where health and nutrition professionals can advise clients on what they can do to improve their gut health and therefore overall wellbeing. We look forward to our research widening and deepening further to improve our understanding in this vital area.
Get involved in the discussion on social media: @Nutrilicious @NutriWebinar #lifelonglearning #feedingthegut
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An extensive detailed analysis of the current scientific evidence into omega-3 seems to have thrown a spanner in the works for heart health dietary advice.
Conducted by Cochrane, the review concludes that there is no correlation between cardiovascular health and intakes of the long chain omega-3 fats eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) over a one- to six-year period.
Long chain omega-3 fats have long been associated with reductions in blood triglycerides, blood pressure and thrombosis; producing anti-inflammatory and anti-arrhythmia effects as well as improving endothelial function and insulin sensitivity.
This most recent publication will raise many eyebrows within the heart health professional arena and likely to be taken up by media editors who seem to enjoy questioning the trustworthiness of public health guidelines. These recommend a diet including omega-3, especially found in oil-rich fish such as salmon, tuna and mackerel.
So, do we need to change dietary guidelines on the importance of omega-3 and oil-rich fish?
Before we jump the gun, it’s important to put things into context:
1. The shortcomings of the review
a. The studies investigated in this review predominantly used omega-3 supplements. Thus the outcomes cannot be related to oil-rich fish consumption which is the main dietary source of EPA and DHA.
b. The studies were also of one to six years’ duration, which is a relatively short period to assess disease and mortality risk. And conclusions cannot be reached for a lifetime consumption of foods rich in EPA or DHA.
c. Many of the studies may not have used adequate number pf subjects in the studies to elicit a result. This is especially the case for studies conducted in healthy individuals (and therefore low risk of heart disease), which would require very high numbers to demonstrate a difference in the omega-3 and non-omega-3 study groups.
d. Any studies conducted over the last two decades of people at risk of cardiovascular disease (CVD) will be in individuals already medicated with statins and other cardio-protective drugs, which may mask the effect, if any, of additional omega-3.
2. Omega-3 benefits go beyond heart health
Long chain omega-3 fats are critical for eye and brain development of the foetus and young children. Therefore, food sources should be included in a healthy balanced diet of children and adults planning for a family.
3. Oil-rich fish is not just omega-3. It offers so many health benefits.
a. Unlike omega-3 supplements, oil-rich fish is a rich source of not only the long chain omega-3 fats but also of selenium, zinc, vitamin D and iodine; woefully lacking in the UK diet.
b. Oil-rich fish has a healthier fat profile when compared to red meat and other animal proteins. Replacing saturated fat with unsaturated fat in the diet has been proven to have a positive effect on blood lipids and cardiovascular health (as confirmed by Cochrane’s 2015 review and the SACN’s & the WHO’s draft 2018 reports). See our saturated fat blog
Indeed, the authors themselves remind us of the other nutritional benefits of oil-rich fish and that this review does not negate public health advice that consuming oil-rich fish is beneficial to health.
The Nutrilicious view
Taking vitamin and mineral supplements as a substitute for eating a healthy balanced diet has never been encouraged by health professionals. However, dietitians recognise that when demands for specific nutrients are high, or when an individual’s nutritional intake is at proven risk of being compromised, supplements can play an important role. For example, pregnancy and folic acid; under-5 year olds and vitamins C and D; or sufferers of osteoporosis and calcium and vitamin D.
Therefore, these findings do not come as any surprise: omega-3 supplements are not a solution to better heart health. There are numerous dietary and lifestyle factors that impact on heart health. It should always be about food rather than the benefits of single nutrients.
As Linda Main, Dietitian and dietary advisor for cholesterol charity HEART UK, explains: “We continue to advise the lifelong consumption of a heart healthy diet centred around eating whole foods rather than the emphasis being on nutrients.
“Eating patterns such as the Mediterranean, DASH or the UCLP© diets result in the consumption of a nutritionally appropriate diet. This is characterised by eating plenty of vegetables, fruits, wholegrains, vegetable proteins such as nuts and soya, seeds, vegetable oils and spreads. In those who consume animal proteins, the inclusion of low fat dairy, lean and largely unprocessed meat and white and oily fish and seafood are recommended.
“Omega-3 supplements are not currently advised by HEART UK and would not be our first choice, except when prescribed by a recognised qualified health professional or when needed to safeguard the intake of the essentially fatty acid – alpha-linolenic acid.”
As oil-rich fish is an excellent low saturated fat protein source, and the main dietary source of long-chain omega-3 fats as well as other crucial nutrients, it should continue to be part of dietary guidelines.
Additionally, for those wishing to follow a more plant-based diet, it’s reassuring that the report finds consumption of the shorter chain omega-3 fats found in plant foods (like rapeseed and soya oil) has cardio-protective qualities. This supports findings from population studies that vegetarians and vegans have a lower incidence of cardiovascular events and mortality compared to non-vegetarians.
Current UK heart health dietary advice remains unchanged:
- Lower the amount of food eaten which is high in saturated fat and replace it with foods high in unsaturated fats (which Cochrane’s 2015 review supports, SACN 2017 Saturated fat draft guidance).
- Increase our intake of fibre (especially from beans, pulses, oats and barley), nuts.
- Consume at least five servings of fruit and vegetables daily.
- Reduce intakes of red meat and avoid/limit processed meat.
- Consume two portions of fish weekly – one of which should be oil rich.
- Increase intakes of leaner and plant-sources of protein.
- Use sterol or stanol fortified products (if blood cholesterol is raised after other dietary changes have been made).
It’s interesting to note that, unlike the US, the UK does not (and has never) recommended taking dietary supplements of omega-3 fish oil.
For up to date expert advice on heart health visit: heartuk.org.uk
Saturated fat and heart health reports
Supplements for specific groups
NHS UK: Vitamins for children; Vitamins, supplements and nutrition in pregnancy
Vegetarian and vegan diets and health outcomes
- Rizzo N, Jaceldo-Siegl K, Sabate J et al. Nutrient profiles of vegetarian and non-vegetarian dietary patterns. J Acad Nutr Diet.. 2013;113(12):1610-9.
- Sobiecki J, Appleby P, Bradbury K et al. High compliance with dietary recommendations in a cohort of meat eaters, fish eaters, vegetarians, and vegans: results from the European Prospective Investigation into Cancer and Nutrition-Oxford study. Nutr Res.. 2016;36(5):464-77.
- Springmann M, Godfray H, Rayner M et al. Analysis and valuation of the health and climate change cobenefits of dietary change. Proc Natl Acad Sci U S A.. 2016;113(15):4146-51.
- Clarys P, Deliens T, Huybrechts I et al. Comparison of nutritional quality of the vegan, vegetarian, semi-vegetarian, pesco-vegetarian and omnivorous diet. Nutrients.. 2014;6(3):1318-32.
Cochrane is an established body of researchers, health professionals and patients across the globe renowned for their high quality scientific reviews of nutrition and health evidence.
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This week, the Daily Mail and the Independent reported that showing the calorie content of meals in restaurants can help lower people’s calorie intake.
This is based on a systematic review of 28 studies, which concluded that nutritional labelling on restaurant menus can reduce the amount of energy (i.e. calories) purchased.
Overall, it was found that nutritional labelling could reduce calorific intake by up to 12% – around 72 calories for a typical 600kcal meal. That’s equivalent to three boiled new potatoes or around 150ml of juice.
Behind the headlines: the Nutrilicious dietetic view
This study is very relevant, considering that on average we eat out for around a quarter of our meals. These meals can often be served as large portions and can be high in sugar and salt.
More and more restaurants in the UK are now providing the nutritional values of meals, which are often available online. They include Nandos, Starbucks, Prezzo, Wagamama, Zizzis, Giraffe and many more. However, previous research has only shown mixed results as to the effects of having the nutritional values available.
There are some limitations to the review – many of the individual studies it’s based on were graded as poor quality. Nevertheless, it provides evidence that displaying nutritional values to restaurant menus may help to lower calorie intake in individuals.
Another weapon in the battle against obesity
Just this week, Cancer Research UK released a report showing that on current trends 70 per cent of millennials – those born between the early 1980s to mid-1990s – will be overweight or obese by the age 35 to 45.That’s more than any other generation since records began. The UK is already the most overweight nation in Western Europe, with obesity rates rising even faster than in the US. We know definitively from the McKinsey Global Institute Report on Overcoming Obesity: an initial economic analysis that we need as many nudge strategies as possible to help overcome this very serious obesity issue.
Professor Theresa Marteau, the review’s lead author and head of the Behaviour and Health Research Unit at Cambridge University, summed it up: “This evidence suggests that using nutritional labelling could help reduce calorie intake and make a useful impact as part of a wider set of measures aimed at tackling obesity. There is no magic bullet to solve the obesity problem, so while calorie labelling may help, other measures to reduce calorie intake are needed.”
Her thoughts are echoed by many experts. Professor Ian Caterson, president of the World Obesity Federation, stated: “Energy labelling has been shown to be effective – people see it and read it and there is a resulting decrease in calories purchased. Combined with a suite of other interventions, such changes will help slow and eventually turn around the continuing rise in body weight.”
Sue Davies, Which? food policy expert, says it’s not just the experts who believe access to more information is important: “This research highlights the value of calorie information and why it is so important that it is provided more widely for people when eating out. In a recent Which? survey, 63% of people agreed that calorie information should be provided on the food in cafes and restaurants for transparency.”
The United States is leading the way on this front: the Food and Drug Administration recently implemented a policy whereby restaurants with 20 or more locations must show calorie counts on their menus from May 2018. It will be interesting to monitor the impact.
There are many measures that are needed to help reduce obesity, and the serious health issues that it causes. Ensuring nutritional values are available to consumers may be a simple strategy amongst many that are needed to help individuals take steps to make wiser meal choices.
There are other steps we can take to help us make healthier choices when eating out. The NHS provides some useful advice and tips
At Nutrilicious, we enjoy helping all organisations to implement, measure and communicate nudge strategies to help the nation overcome the urgent problem of obesity. If you would like to discuss how your organisation could contribute, please get in touch – we would be more than happy to discuss and help.
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Popular in the news this week is the story linking eating ‘ultra-processed’ foods and cancer, as reported by the Independent (‘Processed food, sugary cereals and sliced bread may contribute to cancer risk, study claims‘) the BBC the Daily Mail and The Guardian.
These headlines are based on a study published in the British Medical Journal this month. In the study, foods were classified based on the NOVA system, which relates to the nature, extent and purpose of food processing. Those falling under the category of ‘ultra-processed’ include:
- Mass-produced bread and buns
- Sweet or savoury packaged snacks including crisps, chocolate bars and sweets
- Sodas and sweetened drinks
- Meatballs, poultry and fish nuggets
- Instant noodles and soups
- Frozen or shelf-life ready meals
- Foods made mostly or entirely from sugar, oils and fats
Study details and findings
A cohort of 105,000 people were followed for an average of five years. A 10% increase in the proportion of ultra-processed foods in the diet was associated with a significant 12% increase in the risk of overall cancer and 11% in the risk of breast cancer.
Alongside the original study, the British Medical Journal have also published an editorial further explaining the findings.
Behind the headlines: the Nutrilicious dietetic view
Limitations of the study
While this story has been heavily publicised, there are several limitations of the study which mean we cannot draw firm conclusions:
- Those who ate a lot of ultra-processed foods had other behaviours that have been linked to cancer which could skew the results. They include being more likely to smoke, being less active, consuming more calories overall and more likely to be taking the oral contraceptive. The researchers stated that their impact ‘cannot be entirely excluded’.
- Cause and effect cannot be established for an observational study: we cannot say that ‘ultra-processed foods have caused the increase in cancer’. It is an association found.
- The term ‘ultra-processed’ is still somewhat vague, so it’s difficult to establish which specific foods might be responsible for the increased cancer risk, and why.
- The participants were mainly women who had decided to take part in a health and diet study themselves, so were likely to be interested in their health. This means the sample may not be highly representative of the general public.
That said, we can give credit to the large sample size used in the study giving more reliability to the findings.
Response from Cancer UK
Helping to put this study into context, Professor Linda Bauld from Cancer Research UK responded: “It’s already known that eating a lot of these foods can lead to weight gain, and being overweight or obese can also increase your risk of cancer, so it’s hard to disentangle the effects of diet and weight.”
She also said the study was a ‘warning signal to us to have a healthy diet’ but individuals should not worry about eating a bit of processed food ‘here and there’ as long as they were getting plenty of fruit, vegetables and fibre.
So, can we reduce the risk of cancer?
It’s estimated that one in two people will develop cancer at some point in their lives. Whilst some risk factors for cancer are non-preventable (such as genetics), there are still lots of things we can do to help reduce our risk:
- Eating a healthy, balanced diet
- Limiting red meat and avoiding processed meats
- Maintaining a healthy weight
- Abstaining from smoking
- Keeping alcohol intakes below government guidelines
- Protecting your skin from sun damage
- Knowing your body (e.g. checking for lumps)
For more details on all of the above, go to the National Health Service. The World Cancer Research Fund also carry out a continuous review of the scientific evidence into the subject of diet, lifestyle and cancer risk. Read their cancer prevention recommendations.
This study does not allow us to draw firm conclusions about ultra-processed foods and cancer. However, we should certainly be reminded of the importance of diet and lifestyle in cancer prevention.
After smoking, excess weight is one of the biggest causes of cancer and it has also been estimated that about one third of cancers could be prevented by changing our diet and lifestyle. This includes being a healthy weight, following a healthy diet and engaging in physical activity.
What changes could you make to help reduce your risk?
Reference: Macmillan Cancer and Cancer Research UK
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Plant-based diets made the headlines again this week, with coverage of a study suggesting a vegan diet can prevent type 2 diabetes. It was reported by the Daily Mail (‘Going vegan can prevent overweight adults from falling victim to diabetes’) and Medical News Today.
In the study, 75 participants were put into two groups. One group was asked to follow a low-fat, plant-based vegan diet with no calorie restriction. The other was asked to make no dietary changes for a period of 16 weeks. Participants prepared all their own meals and for both groups, alcoholic drinks were restricted to one per day for women and two per day for men.
All the participants had a Body Mass Index (BMI) between 28kg/m2 and 40kg/m2 (putting them into the ‘overweight’ or ‘obese’ categories), with no history of diabetes.
At the end of the study, the plant-based group reported:
- Marked improvements in beta-cell functioning – these are the cells which produce the hormone insulin, which is important for controlling blood sugar levels (a key factor in diabetes where blood sugar levels are elevated or harder to control).
- A significant increase in how well the body responded to insulin – when the body is less sensitive to the hormone insulin, it increases the chances of developing type 2 diabetes.
- A decrease in BMI and body fat levels – this is important because excess body weight is strongly associated with increased risk of type 2 diabetes.
It was reported that neither group made any changes to their physical activity regimen, nor did they change the use of their medications.
Read more details of the original study
Behind the headlines: the Nutrilicious dietetic view
Whilst this is yet another study showing positive effects arising from a plant-based diet, we must be aware of its limitations:
- Efforts were made to help ensure adherence to the diet (such as dietitian telephone calls to the participants and food diaries completed at the start and end) but this still relies on the honesty and accuracy of the participant.
- As noted by the researchers, the participants used in the study were ‘generally health-conscious individuals’ who were willing to make significant dietary changes. Thus, we cannot be sure findings would be representative of the general population if they were to eat a vegan diet.
- The study is too short and too small to show conclusively that a vegan diet prevents type 2 diabetes.
- The meals were prepared by the participants and thus any changes or fluctuations were not controlled or recorded.
On the other hand, a strength of the study is that it was a randomised controlled trial, which is the gold standard in research for measuring the effectiveness of an intervention.
The link between plant-based diet and reduced risk of diabetes
The researchers recognised that the major factor accounting for the reduced risk of type 2 diabetes in the plant-based group was the weight lost (including visceral fat lost).
The link between the two is well established. Research shows that for every kilogram of weight loss, there is a 16% reduction in risk or type 2 diabetes.*
The generally higher fibre and lower fat content of plant-based diets (which also includes vegetarian diets) would be expected to be helpful in reducing the energy density, and thus total calorie content of the diet. This could help with reducing obesity.
*Hammam et al (2006) Effect of Weight Loss With Lifestyle Intervention on Risk of Diabetes.
In the UK, 11.9 million people are at risk of developing type 2 diabetes: prevention is clearly of great importance. The disease can have both short-term and long-term complications.
Further research will be needed to determine whether a vegan diet could prevent type 2 diabetes, and whether the positive improvements noted in this study require a strict vegan diet or whether the positive effects could be achieved with smaller changes.
Evidence shows the best ways to reduce risk of type 2 diabetes include:
- maintaining a healthy weight;
- eating healthily; and
- keeping physically active,
Adopting principles from a plant-based diet can certainly help with the first two points. The range of benefits of adopting a more plant-based diet are discussed further in last week’s blog.
For more information on reducing risk see Diabetes UK alongside their useful information about veganism and diabetes.
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The rise in popularity of vegetarian and vegan diets is in the news, including stories in the Daily Mail INews. This comes following a release by Kantar Worldpanel of supermarket sales figures and analysis of consumer behaviour. It revealed:
- Over January 2018, one in ten shoppers purchased a meat-free ready meal. This has increased by 15% compared with the same time last year.
- During January 2018, 29% of evening meals were now free of meat and fish.
- Britons consumed 3.9 billion meat free evening meals in the 12 months to October 2015. This rose to 4.3 billion in the 12 months to October 2017.
- As a nation, we consumed 87 million more entirely vegan-friendly meals in 2017 than in 2015.
Announcements of product sales and ranges underscore these figures. In just two examples, it was also reported in the news this week that sales of Quorn (a meat substitute product) have increased globally by 16%. Last month also saw Tesco bring out their own vegan range, Wicked Kitchen, highlighting the increasing demand for more plant-based options.
Behind the headlines: the Nutrilicious dietetic view
There are many reasons why we could be seeing an increase in the popularity of meat free meals.
The trend of ‘Veganuary’ (where individuals adopt a vegan diet for the month of January) is likely to have contributed to the findings which related to the month of January 2018.
Richard Allen, a spokesman for Kantar Worldpanel, emphasised increasing access to meat-free foods: “The surge in vegetarian evening meals over the past year is down to the wider availability of products which make eating meat-free more attractive and practical.”
He continued: “Our ideas about what’s healthy are also changing – we’re more focussed on foods that are natural and less processed and eating a varied diet.”
What are the benefits of a plant-based diet?
The evidence for plant-based diets is growing and can offer many benefits. Indeed, the updated ‘Eatwell Guide’ saw that plant sources of protein were listed ahead of animal food sources of protein. The protein group now has the title ‘Beans, pulses, fish, eggs, meat and other proteins’, highlighting the increased role plant-based diets can play.
Benefits of adopting a more plant-based diet include:
- Research has shown that vegetarian and vegan populations tend to have lower blood pressure, cholesterol levels and rates of cardiovascular disease compared to their omnivorous counterparts. This could be due to less saturated fat in the diet and more polyunsaturated fats, in addition to other cardio-protective components in the diet such as soya and nuts.
- Plant-based diets tend to have a more balanced macronutrient profile. For example, the higher fibre content of plant-based diets is often accompanied by lower fat intakes. This can help reduce the energy density of the diet and thus help reduce the total energy (calorie) intake. This could help prevent people being overweight/obese, and therefore any related negative effects and co-morbidities (e.g. type 2 diabetes, increased cancer risk etc).
- Animal foods are resource intensive (energy, land and water) and thus tend to have higher greenhouse gas emissions compared to plant foods per unit weight.
- Modelling work has shown that reducing the amount of animal foods in the diet will make a critical contribution to climate change mitigation.
- Recent research has suggested that the British government could reduce its healthcare and societal costs by £5.21 billion if just 10 per cent of the UK population emphasised plant-based foods in their diet.
References: Clarkson V, Plant Food Sources of Protein for Optimum Health, Muscle Status and Sustainability – The Evidence and Practice and Schepers J & Annemans L., The potential health and economic impact of plant-based food patterns in Belgium and the United Kingdom. Nutrition 15th December 2017 (in press)
Does this mean meat is off the menu?
Gaining the benefits of a plant-based diet does not have to mean a diet no with meat at all. A ‘flexitarian‘ diet is predominantly plant-based without completely eliminating meat and can be extremely beneficial for health and reducing carbon footprints.
Indeed, meat, poultry and fish are nutritious foods and can provide a range of nutrients beneficial for health. We are advised by the NHS to have two portions of fish per week, one of which is oily. They also advise how meat can fit into the diet.
We welcome findings that plant-based meals are being explored and becoming more popular. We encourage everyone to enjoy a varied diet featuring a wide variety of plant-based whole foods.
Overall, plant-based eating isn’t new. It’s not radical. And it’s definitely not about cutting things out. A plant-based diet shouldn’t be defined by what it excludes, but by what it includes. The core message is ‘put plants first’. Instead of planning meals around meat, bring veggies, fruits, whole grains, pulses, legumes, nuts and seeds from the side of the plate to front and centre.
It doesn’t have to be wholesale change: many benefits can be achieved by simply reducing intake of meat rather than following a strict vegetarian or vegan diet. We recommend making small steps to include more plant-based foods and meals in your diet, to benefit your health and the planet.
If you do decide to go further, the NHS gives advice on ensuring a vegetarian or vegan diet is balanced. The British Dietetic Association are part of an important alliance with the Vegan Society to share the message that all well-planned vegan diets can support healthy living in people of all ages.
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