Wednesday, 22 January 2014

Is it healthier to go veggie?

On the eve of speaking at a House of Lords debate on the health impacts of vegetarian and vegan diets, EBLEX nutrition manager Maureen Strong took a scientific, evidence-based look at the key nutritional issues

There are a number of reasons why people choose not to eat meat. Respect for sentient life (as opposed to plant life), religious belief, animal rights, health issues or for cultural, environmental, aesthetic or economic considerations. My focus here is purely on the advantages and disadvantages of vegetarian and vegan diets from a health perspective.

It may not be the most exciting or ‘sexiest’ of messages but the key to good health is a balanced diet, based on moderation in all things, plus an active lifestyle. Diversity in the diet is an extremely important component of healthy eating. Both vegetarian and non-vegetarian diets can be either good or bad for health, depending on the variety and quantity of foods selected. Dietary deficiencies are most likely to be seen in people with very restrictive diets.

Potential health problems stemming from a poorly balanced diet are much greater for vegetarians than non-vegetarians, especially vegans. Non meat-eating diets are much more likely to lead to deficiencies in calcium, iron and vitamin B12 intake if they are badly planned. A particular danger with poor vegan diets is that they will not provide sufficient energy (calories), especially during infancy, childhood and pregnancy.

My fellow debater for the All Party Parliamentary Food and Health Forum at the House of Lords this week will be Professor Tim Key of Oxford University, who is leading the UK work on the European Prospective Investigation into Cancer and Nutrition (EPIC). This study, involving 500,000 people (around half of them non meat-eaters) from 10 European countries, has been examining the effects of a vegetarian diet on long-term health since 1993.

EPIC has reported that British vegetarians have low mortality compared with the general population. However, in pointing out that vegetarians consume more of the ‘protective’ foods such as fruit and vegetables, the study has stated that any potential health benefits of a vegetarian diet could actually be “attributed to non-dietary lifestyle factors such as a low prevalence of smoking and a generally high socio-economic status, or to aspects of the diet other than the avoidance of meat and fish”.

Vegetarian diets can result in a number of dietary deficiencies for the following reasons:

·         Many of the richest sources of major minerals are found in animal foods

·         Natural dietary sources of vitamin D are limited to animal foods

·        A plant based diet could be limited in the availability of some indispensable amino acids if different plant proteins are not adequately combined

·       High levels of fibre content in vegetarian diets, which includes phytates and oxalates, can impair intestinal absorption of some minerals such as iron, zinc and calcium

·      The iron found in plant foods, eggs and milk is an organic (non-haem) form and has a much lower absorption rate from the intestine than the iron complexed with haem found in animal flesh

·         The richest source of zinc is found in animal foods.

In the literature, the protein, micronutrients and fat found in meat and meat products have been associated with chronic diseases such as cancer and coronary heart disease (CHD). Yet it should be stressed that while meat may contain a few, not clearly defined cancer promoting factors, it also contains a number of cancer protecting elements such as vitamin A, folate and selenium. Moreover, the cancer protecting factors in meat can be optimised by a diet that includes fruit and vegetables.

The British Nutrition Foundation sees it this way: “Vegetarians have been found to be at reduced risk of coronary heart disease (CHD) and some forms of cancer in some studies. It is not possible, however, to disentangle which aspects of the vegetarian lifestyle are associated with the possible protective effect. It is certainly inappropriate to blame any single food, or even diet in general, for the causation of CHD or cancer.”

The fact is meat is a good source of protein, readily available iron, calcium, magnesium, selenium, zinc and a range of B vitamin. Since such a high proportion of women of child bearing age are iron deficient and considering the evidence linking meat consumption to cancer is so weak, eating meat as part of a balanced and varied diet should actually be encouraged.

This blog first appeared on the AHDB website