Brigid McKevith, Senior Nutrition Scientist, British Nutrition Foundation

Vegetarian diets seem to be becoming more popular, although it is difficult to get accurate estimates because no single, accepted definition of the term 'vegetarian' exists. The term covers a wide range of dietary patterns (e.g. a lacto-ovo-vegetarian excludes all flesh foods but includes dairy produce and eggs while a vegan avoids all foods of animal origin); consequently food intake and therefore nutrient intakes can vary greatly.

The key nutritional issue for people following a vegetarian or vegan eating pattern is the adequacy of their diet. While in the UK meat and meat products are an important source of a range of nutrients such as iron, zinc, vitamin B12 and vitamin D, a well-planned and balanced vegetarian or vegan diet can also be nutritionally adequate. These nutrients need to be found from other sources which are either naturally rich in the particular nutrient (e.g. dried apricots are a good source of iron) or are fortified (e.g. some breakfast cereals are fortified with iron). While some vegans may have low intakes of vitamin B12, vitamin D, calcium and iodine, vegetarian and vegan diets are likely to contain more of other nutrients such as folate, fibre, phytohemicals and carotenoids than the diets of some fish- and meat-eaters.

Some large studies have shown that vegetarians have a lower overall mortality rate than the general population. However this advantage is not seen when vegetarians are compared with similar health conscious non-vegetarians. A high intake of plant foods is associated with a reduced risk of some cancers and several studies have found an increased risk of colorectal cancer amongst those with the highest intakes of meat and the lowest intakes of fibre. However, there is no evidence that being vegetarian per se confers a protective effect. Improvement in a number of established risk factors for cardiovascular disease (CVD) including a more favourable blood lipid profile, a lower body mass index and lower blood pressure have been reported in vegetarians and vegans. Conversely, several studies have found vegetarians to have high plasma concentrations of homocysteine, an emerging risk factor for CVD. These findings need to be viewed in the context of other lifestyle differences e.g. activity pattern, smoking habits and alcohol intake.

There are healthy and unhealthy vegetarian diets just as there are with omnivorous diets. While vegetarian diets may offer some benefits, more research is needed to establish if a vegetarian diet per se can provide long term health benefits. However, it is known that a diet rich in fruits, vegetables and whole grain cereals and low in saturated fats can decrease the risk of a number of chronic diseases. Such a diet should be encouraged for everyone, along with other appropriate lifestyle choices, regardless of whether meat, fish and dairy foods are included.

The British Nutrition Foundation has recently published a briefing paper on vegetarian nutrition which can be ordered at www.nutrition.org.uk .

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