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.