This month, the British Medical Journal (BMJ) published a review on dietary patterns and chronic disease prevention. It aimed to answer questions including whether specific foods actually provide health benefits; and whether exclusion diets – vegetarian, vegan, avoidance of gluten or lactose – are the key to good health.
Here we put it in the context of the advice we’re being by government as to what we should eat to be healthy.
Key messages from the BMJ review:
- Prioritise eating fruits, vegetables, whole grains and fish to best help prevent chronic disease risk. Equally, lower consumption of red and processed meats and sugar-sweetened drinks.
- Eating more nuts, legumes, vegetable oils, fermented dairy products and coffee are further likely to provide benefit.
- Evidence comes from prospective observational and intervention studies, each study design having different strengths and limitations. Both types of studies should contribute to the evidence base.
- New analytical approaches are still needed for nutrition research.
How do the findings fit in with current advice?
The key messages promoted from the review support the government’s advice for healthy eating, the Eatwell Guide.
- Fruit and vegetables
BMJ: Found that fruit and vegetables were associated with lower risk of cancer, coronary heart disease and stroke.
GUIDANCE: It’s recommended we eat at least five portions of fruit and vegetables per day. See this factsheet (https://www.bda.uk.com/foodfacts/FruitVeg.pdf) from the British Dietetic Association (BDA) on how to help achieve this.
- Whole grains
BMJ: Wholegrain consumption was related to lower risk for most diseases studied (the endpoints).
GUIDANCE: We are advised to have at least 30 grams of fibre per day. Wholegrains can certainly help us achieve this. See the British Dietetic Association fibre fact sheet for more information https://www.bda.uk.com/foodfacts/fibrefoodfactsheet.pdf.
BMJ: Fish consumption was found to reduce the risk of coronary heart disease and stroke.
GUIDANCE: The government recommend we consume 2 portions of fish per week (one portion is around 140g), one of which should be oily. Find out more from the National Health Service.
- Red and processed meat
BMJ: Consumption of red and processed meats increased the risk for most of the endpoints.
GUIDANCE: This supports the latest review by the World Cancer Research Fund (WCRF) discussed in our previous blog.
Their report recommends we consume no more than about three portions per week, which is around 350–500g cooked weight (or 525–750g raw weight) a week. To help give you an idea of what that means:
- One pork chop is 75g cooked weight (110g raw)
- One medium steak is 145g (210g raw)
- A portion of beef mince in Bolognese averages about 140g cooked weight (200g raw).
WCRF recommend that for cancer protection we eat little or no processed meats (e.g. sausages, ham, bacon).
- Sugar sweetened drinks
BMJ: Drinking sugar-sweetened drinks was associated with increased risk of type 2 diabetes, coronary heart disease and stroke.
GUIDANCE: Excessive sugar intake (for which sugar-sweetened drinks are a major contributor of) remains a major problem in the UK. Just a couple of months ago, the UK sugar tax was introduced as one of the many strategies employed to help combat this public health issue.
The government’s advice for limiting free sugars supports BMJ’s findings.
- Nuts, fermented dairy products, coffee and others
The review states that higher consumption of nuts, legumes and vegetable oils are likely to confer further benefits. This helps support the benefits behind a more plant-based diet. For more information see the BDA’s factsheet (https://www.bda.uk.com/foodfacts/plant-based_diet).
Fermented dairy products (such as yogurt, kefir) were also mentioned because links were found between these foods and a reduced risk of cardiometabolic disease. Whilst fermented dairy foods can form part of a balanced diet, the research is inconclusive at this stage. The British Nutrition Foundation discuss the area of fermented foods and why it can be difficult to draw conclusions at this stage.
Finally, studies found a reduced risk of many endpoints by drinking 3-5 cups of coffee per day. We often see headlines focusing on negative effects of coffee, when in fact there is a lot of research for beneficial effects.
Coffee can certainly help meet our daily fluid requirements and should not be discouraged. We must bear in mind that due to the caffeine, it should be limited to two cups per day (instant coffee) for pregnant women.
The review also goes through the studies found for specific dietary patterns, highlighting that most reliable evidence for chronic disease prevention lies with following a Mediterranean diet. This type of diet generally refers to a diet encouraging high intake of fruits, nuts and seeds, vegetables, fish, legumes and cereals and reducing intake of meat and dairy products. Moderate intakes of alcohol and olive oil are also components of this diet.
This latest BMJ review supports the government’s messages for healthy eating. A significant proportion of the foods shown to be of benefit (such as fruit and vegetables, wholegrains, legumes, nuts and vegetable oils) are plant-based and these should be encouraged as part of our whole diets for both health and environmental reasons.
– There are often flaws to research in the field of nutrition, as discussed the BMJ review.
– Concentrate on the whole diet rather than just focusing on individual foods or groups.
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The latest National Diet and Nutrition Survey (NDNS) highlighted that 91% of women of childbearing age (16 to 49 years) in the UK have folate levels that are too low.
It’s in the early stages of pregnancy that the foetus rapidly develops spine and nerve cells. Low folate levels increase the risk of foetal Neural Tube Defects (NTDs), such as spina bifida, so folic acid is recommended as a supplement.
Yet a recent survey of 750 pregnant women carried out by baby charity Tommy’s showed that:
- One in five women started taking folic acid before contraception
- One in six women did not take folic acid at all
Previous large studies have seen similar low levels of folic acid intake. For example, a study of nearly half a million women in England and the Isle of Man found less than 1 in 3 women had taken folic acid supplements before pregnancy.
What is the current advice for folic acid supplements?
Women planning a pregnancy (ideally two to three months before conception) are advised to take a 400-microgram supplement of folic acid until the 12th week of pregnancy.
Women with diabetes and those who have had a pregnancy previously affected by NTDs may need a 500-microgram supplement. For more information on who may need higher doses, see the National Health Service.
The advice for taking a supplement is in addition to eating foods rich in folate, the natural form of folic acid. Top sources of folate include green leafy vegetables, citrus fruits, beans and legumes, yeast extract and fortified foods. Eating these foods alone will not meet the demands of a pregnant women and their developing baby.
For more information, the British Dietetic Association (BDA) have produced a factsheet on folic acid.
Folic acid fortification: the UK needs to get up to speed
Over 80 countries have introduced mandatory fortification of flour with folic acid, to help reduce the number of babies affected with NTDs.
The UK hasn’t yet followed suit. In 2002, the Food Standards Agency (FSA) advised against mandatory fortification because folic acid supplements were believed to mask the anaemia caused by B12 deficiency (which causes ongoing nerve damage) and lead to an increased risk of colon cancer in certain groups.
However, more recent research has found no significant links between high doses of folic acid and cancer. In addition, countries that already have mandatory folic acid flour fortification in place haven’t seen an increase in people developing nerve damage as a result of B12 deficiency.
Highlighting the benefits, the US has seen a 23% fall in pregnancies with NTDs since the policy was introduced in 1998. A 2016 study published in the British Medical Journal estimated that 2,000 pregnancies associated with NTDs would have been prevented if the UK had adopted the same fortification as the US from 1998.
The most recent update from the Scientific Advisory Committee on Nutrition, which considers all the evidence for and against folic acid supplementation, echoed previous advice they had given supporting mandatory fortification of flour with folic acid in the UK. The FSA also now support mandatory fortification. Unfortunately, the UK government has remained unwilling to introduce regulation.
The BDA have information on how their members can help support the introduction of folic acid fortification to put pressure on the UK government.
What’s next for folic acid intake?
Folic acid plays a crucial role for the prevention of NTDs in babies but many women are not taking the recommended supplement before pregnancy.
In response to their findings, Tommy’s have created a new online tool, Planning for Pregnancy, which helps women plan for healthy pregnancies. It was created alongside the Royal College of Obstetricians and Gynaecologists, Public Health England and the UCL Institute for Women’s Health. The tool provides advice on folic acid and other factors involved for a healthy pregnancy and will hopefully prove to be a useful resource for women planning to become pregnant. Dietitians, nutritionists and all involved in food and health communications have a role in promoting such resources.
At a policy level, we hope to see the UK government enforce mandatory fortification of flour in the UK as a simple way to increase folic acid for everyone, in light of the wealth of evidence to support the measure.
Of course, in addition to taking folic acid pre-conception, there are other points to be aware of to help ensure a healthy pregnancy including avoidance of smoking, avoiding alcohol, being a healthy weight before pregnancy (BMI between 18.5kg/m2 and 24.9kg/m2) and engaging in regular moderate exercise.
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One in two people in the UK will be affected by cancer at some point in their lives. The important new expert report by the World Cancer Research Fund (WCRF) has been published, evaluating the links between diet, nutrition, physical activity and cancer and the past decade of cancer prevention research.
It finds that around 40% of cancers could be prevented by making healthy lifestyle choices.
Here’s a summary of the key findings, along with WCRF recommendations about how we can best help prevent cancer.
Key lifestyle factors linked to cancer
1. Body fatness
- There is strong evidence that greater body fatness is a cause of many cancers – including pancreatic cancer, liver cancer and ovarian cancer. Science in relation to the link has grown over the last decade.Rates of overweight and obesity have been rising in most countries. Figures released on obesity just this week show that in the UK almost 60% more children in their last year of primary school are classified as ‘severely obese’ than in their first year.WCRF says that if current trends continue, being overweight or obese is likely to overtake smoking as the number one risk factor for cancer.
- Whilst greater weight gain in adulthood increases the risk of post-menopausal breast cancer, evidence showed that being overweight or obese as an adult before menopause decreases the risk of pre-menopausal breast cancer. Also, being overweight or obese between the ages of 18 and 30 years decreased the risk of pre- and postmenopausal breast cancer.Despite the findings, it is important to know that WCRF recommend maintaining a healthy weight throughout all stages of life.
WCRF Expert Panel opinion – Keep weight within the healthy BMI range (18.5kg/m2 – 24.9kg/m2) and avoid weight gain in adult life. WCRF explain more about BMI and provide a useful BMI calculator.
2. Dietary factors
a. Wholegrains, vegetables and fruit
- Wholegrains and other foods containing dietary fibre decrease the risk of colorectal cancer. This includes both foods that naturally contain fibre and foods that have had fibre added.
- Beta-carotene in foods or supplements is unlikely to have a substantial effect on the risk of prostate cancer.
- Foods contaminated by aflatoxins (toxins found in some fungi) increase the risk of liver cancer. Find out more about what this means on the WCRF website.
- Foods preserved by salting increase the risk of stomach cancer.
WCRF Expert Panel opinion – For wholegrains and other foods containing dietary fibre, the evidence shows that, in general, the more people consume, the lower the risk of some cancers.
We are advised to consume at least 30 grams of fibre per day (see the fibre fact sheet from the British Dietetic Association for more information on how to achieve this).
A diet high in all types of plant foods is recommended including at least five portions of vegetables and fruit per day. This poster from WCRF shows what counts as a portion.
b. Animal products
- Red meat and processed meat increase the risk of colorectal cancer.
- Cantonese-style salted fish increases the risk of nasopharyngeal cancer.
- Dairy products decrease the risk of colorectal cancer.
WCRF Expert Panel opinion – For people who eat meat, limit consumption of red meat, such as beef, pork and lamb, to no more than three portions per week: 350–500g cooked weight. Eat little, if any, processed meat.
c. Alcoholic drinks
- Consuming alcoholic drinks increases the risk of:
- Mouth, pharynx and larynx cancers
- Oesophageal cancers
- Breast cancer (pre- and post-menopause)
- Two or more alcoholic drinks a day increase the risk of colorectal cancer.
- Three or more alcoholic drinks a day increase the risk of stomach cancer and liver cancer.
- Up to two alcoholic drinks a day decrease the risk of kidney cancer (though note, WCRF advise that this is far outweighed by the increased risk for other cancers).
WCRF Expert Panel Opinion – The evidence shows that, in general, the more alcoholic drinks people consume, the higher the risk of many cancers.
WCRF advise that for cancer prevention, it’s best not to drink any alcohol at all. Indeed, there is no threshold for the level of consumption below which there is no increase in the risk of at least some cancers.
3. Physical activity
- Being physically active decreases the risk of:
- Colon cancer
- Breast cancer (post-menopause)
- Endometrial cancer
- Vigorous physical activity (e.g. running or fast cycling) decreases the risk of:
- Pre- and post-menopausal breast cancer
WCRF Expert Panel Opinion – The evidence implies that, in general, the more physically active people are, the lower the risk of some cancers.
We are advised to do at least 150 minutes of moderate intensity activity (examples include brisk walking, cycling, household chores, swimming, dancing) or 75 minutes of vigorous activity (examples include running, aerobics, squash, netball, fast cycling) per week.
4. Other factors related to cancer
The report also covers links between cancer and other dietary factors (including glycaemic load, vitamin supplements and non-alcoholic drinks); height and birth weight; and lactation. For more information, see the summary report.
The 10 cancer prevention recommendations
The report includes 10 key recommendations for cancer prevention. Shown here as an overview infographic, there’s lots more useful detail in the report itself.
For lifestyle factors as discussed within this report, incorporating the recommendations into our lives as a whole package, rather than just focusing on a few individually, will be the most conducive for cancer prevention. It is interesting to know that between 30-50% of all cancer cases are estimated to be preventable through healthy lifestyles and avoiding exposures to occupational carcinogens (substances capable of causing cancer), environmental pollution and certain long-term infections.
NEW resources to help with cancer prevention:
- Cancer Health Check – A new online questionnaire check has been launched to help individuals find out where they are doing well and where they could make changes to their lifestyle to help reduce the risk of cancer.
- Toolkit – WCRF have published a downloadable toolkit which shows key points from the report using lots of visual representations of the findings.
- Interactive Cancer Risk Matrix – This tool gives information on how different aspects of diet, as well as body weight and physical activity, might be linked to cancer risk based on the strength of the evidence.
- Individual sections of the report – these can be accessed digitally as PDFs or as toolkits. This allows us to zoom in on specific dietary factors or different cancers and find out the evidence from the main report.
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This week, Public Health England (PHE) published their first assessment on the government’s sugar reduction programme, introduced to help reduce rates of childhood obesity.
The food industry – including retailers, manufacturers, restaurants, cafes and pub chains – was given the target to cut 20% of sugar from a range of products by 2020, with a 5% reduction in the first year. The first year of the programme was from August 2016 to August 2017.
What does the assessment show?
- Retailers and manufacturers have achieved only a 2% reduction in sugar.
- Sugar has been reduced by 11% by retailers and manufacturers in drinks that are included in the Soft Drinks Industry Levy and average calories per portion has been reduced by 6%.
- New guidelines have been published for the drinks industry to reduce sugar in juice and milk-based drinks.
Importantly, PHE highlight that there are forthcoming sugar reduction plans from the food industry and that some changes of products were not captured in the data (as the changes took effect after the one-year mark measured). This all points towards hopefully seeing greater reductions in future assessments.
Measuring the progress
Ten food categories were measured that contribute the most sugar to children’s diets, although breakfast pastries and cakes were not included due to insufficient data. Some of the key findings from the assessment include:
- Reductions in sugar levels were seen across five of the categories.
- Yogurts and fromage frais, breakfast cereals, and sweet spreads and sauces have all met or exceeded the initial 5% sugar reduction ambition.
- Biscuits and chocolate confectionary have seen no change at all in sugar levels.
- The puddings category has actually seen a slight (1%) increase in sugar content overall.
- It has been noted that for the eating out of home sector, portion sizes in products likely to be consumed in one go are substantially larger (on average more than double) those of retailers and manufacturers.
- Calories in products likely to be consumed in one go have reduced in four categories. Of these, ice cream, lollies and sorbets, and yogurts and fromage frais have reduced average calories by more than 5%. Often this is due to smaller portion size.
The British Retail Consortium (BRC) provided an interesting infographic showing how the food industry has been cutting sugar.
In response to the PHE assessment, Andrew Opie, Director of Food Policy at the BRC, stated: “Retailers are fully committed to helping improve the health of their customers and have led the way in reducing sugar in their products. Thousands of tonnes of sugar have been removed from retailers’ own product ranges to date and continuing work will result in even greater reductions over the next few years.
“Retailers have shown that reducing sugar levels across a wide range of products is possible but all food businesses must follow suit if we are to see significant reductions in the level of sugar in the nation’s diet.”
The British Dietetic Association‘s Head of External Affairs, Jo Instone, said: “We recognise that there are limitations in the data and that these are the early stages of the reformulation programme. However, it is disappointing to have such significant gaps and for a number of manufacturers to have refused to allow information on their progress to be published.”
“Clearly, it will be important for the BDA, the Obesity Health Alliance and others to continue working with Public Health England and the government to drive this programme forward. We would hope that the 2019 report can fill in a number of gaps and that we will see more substantial progress made across the board.”
Milk based drinks and juice
Following our concern about sugar levels in fruit juice, we’re pleased to see new plans by PHE encouraging the drinks industry to achieve the following by mid-2021:
- Reduce sugar in juice-based drinks by 5% (excluding single juice – that is, products with juice from a single fruit with nothing added to it).
- Cap all juice-based drinks (including blended juices, smoothies and single juices) likely to be consumed in one go to 150 calories.
- Reduce sugar in milk (and milk substitutes) based drinks by 20% and cap products likely to be consumed in one go to 300 calories.
Some progress has been made, but it seems we’re still well off hitting targets for sugar reduction. It’s clear that more work is needed – by manufacturers and retailers, but also cafes and restaurants, where calorie intake tends to be significantly higher.
The next progress report from PHE is due in Spring 2019 and should give a clearer picture on the programme’s progress.
Of course, this is only one of the many strategies needed to help combat the obesity crisis. Along with the BDA and many others, we’re looking forward to hearing government measures for issues including broadcast advertising, in-store promotions and other interventions to help tackle the problem.
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In recent years, there has been much debate about whether the government are providing the correct advice for saturated fats in the diet. We have seen many claims that saturated fats may in fact be good for us, with recent headlines causing confusion including:
“Is butter back and is sat fat good?”
“‘Saturated fat good for you’, expert claims”
“Saturated fat link with heart disease questioned”
So we are very pleased to have the much-anticipated Scientific Advisory Committee on Nutrition (SACN) draft review into saturated fat published this week.
SACN’s draft recommendations are:
- The population average contribution of saturated fat to total calorie intake should be no more than 10%. This means no more than 30g of saturated fat for men, no more than 20g for women and less for children.
- Dietary saturated fats should be substituted with unsaturated fats. Foods like fish (especially oily fish such as mackerel, salmon and trout), unsalted nuts, seeds and avocado are sources of unsaturated fat.
The rationale behind this is the wealth of evidence linking saturated fats to an increased risk of high blood cholesterol, which can increase the risk of cardiovascular disease (CVD).
SACN advise that reducing saturated fats can help improve blood lipids and also blood glucose control. There is also no evidence that reducing intake of saturated fat increases risk of any of the outcomes considered: cardiovascular disease, blood lipids, blood pressure, diabetes, dementia and some cancers.
This new review from SACN helps support advice that we should not be promoting regular use of coconut oil (another trend of recent years: see our coconut oil blog). Indeed, coconut oil is made up of around 85% saturated fats, with 1 tablespoon providing a hefty 12g of saturated fat.
How does this compare to previous guidance?
The previous review was undertaken by SACN’s predecessor Committee on Medical Aspects of Food Policy in 1994 and concluded that saturated fat intake should be no more than 10% of total calories for adults and children aged five and older.
SACN have come to the conclusion that the new evidence supports and strengths the above original recommendation and hence there are no changes to the current government advice.
How much saturated fat do we eat in the UK?
In the UK, average saturated fat intakes are at around 12% of calories. There are improvements to be made to meet the 10% target.
Most of our intake comes from milk products (such as whole milk and cheese), cereal products and meat products.
What are the best saturated fat substitutes?
The review considers what we substitute saturated fat with and the effects on our health. It concludes that the best is to replace saturated fats with monounsaturated fats and polyunsaturated fats.
This fully supports recent consensus on saturated fat reductions from the World Health Organisation 2016 meta-analysis focusing on impact on serum lipids, and the 2015 Cochrane review by Hooper focusing on cardiovascular disease outcomes. Both come to more or less the same conclusions. (If you’re interested in the basic chemistry of fats, do read the WHO analysis, it’s particularly interesting!)
When discussing substitution of saturated with carbohydrates, they highlighted that there is ‘adequate’ evidence that when saturated fats are replaced with carbohydrates alone, this is linked with an increased risk of heart disease.
However, SACN states there was a lack of good quality evidence that differentiated between types of carbohydrates and their resulting effects on heart disease. Different carbohydrates can have different effects on the body (for example, due to varying fibre content). Further research that differentiates between the types of carbohydrates is clearly needed.
In a nutshell, the draft guidelines support current advice that we need to reduce saturated fat intake and replace it with unsaturated fats.
For more information on how to lower your saturated fats intake, see Heart UK’s website.
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