Vegetarian and vegan diets Vegetarians and vegans have to take extra care that they get all the necessary nutrients from their diet.

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How many people follow these diets? What is a vegetarian and vegan diet?

Nutrient intake Vegetarian diet and health

Are vegetarian diets suitable for all?

About five per cent of the UK population consider themselves to be vegetarian, according to the National Diet and Nutrition Survey. That's about 3 million people, with women more likely to call themselves vegetarian than men. The figure for vegans is smaller - consumer surveys suggest they make up about one per cent of the UK population.

People choose to follow vegetarian and vegan diets for a variety of social, religious, lifestyle, moral and health reasons.

Strictly speaking, a vegetarian diet is one that includes only cereal products, nuts, seeds, and fruit and vegetables, and may or may not include the use of dairy products and eggs. Vegetarians do not eat meat, poultry, fish, shellfish or foods containing meat products.

Vegans will not eat dairy products, eggs or any other food derived from animals.

Probably the most common type in the UK are lacto-ovo vegetarians, who include eggs and dairy products in their diet. Lacto-vegetarians eat dairy products but not eggs.

For both vegetarians and vegans, avoiding certain products can be tricky. For example, animal fat and ingredients such as gelatine may be used in manufactured foods. Rennet, which is extracted from the stomach lining of cows, is often used in cheese making.

In many cases, there are vegetarian alternatives to these ingredients so, if you are considering a vegetarian or vegan diet, it's well worth taking some time to read food labels.

There are also several variations on the above diets. Pescatarians will include fish and/or shellfish in their diet, and semi or demi-vegetarians will occasionally include meat or poultry. The more foods that are excluded, the greater the care that's needed to ensure a balanced diet.

Vegetarians should follow the same healthy eating guidelines as meat eaters, as outlined by the Food Standards Agency's 'eatwell plate'. They should choose foods from all the main food groups, including alternative sources of protein such as low-fat dairy products, eggs and pulses.

Several large studies have examined the nutrient intake of vegetarians and meat eaters, and most have shown no difference in nutrient intake. Vegetarian or vegan diets may be more healthy or less healthy than diets of meat eaters, depending on specific food choices.

For good health, vegetarians and vegans should consider certain factors.

Protein

Following a vegetarian diet involves more than just avoiding meat and meat products. A sensible non-meat eater's diet contains alternative sources of non-meat protein. This shouldn't just be limited to dairy products but can include other sources of protein such as pulses (for example, lentils), nuts and seeds, eggs, soya products such as tofu, and vegetable protein foods.

Eating a variety of non-meat protein foods will ensure you get all the essential amino acids (the 'building blocks' of protein) your body requires.

Iron

The most easily absorbed iron is found in meat. Iron from plant foods is less well absorbed, which may increase your risk of iron deficiency. But with good food choices, the risk of iron deficiency should be no greater for vegetarians than for meat eaters.

Selenium

Selenium is an antioxidant found in meat and fish, and non-meat sources include Brazil nuts, seeds, grains, soya beans and mushrooms. The selenium content of plant foods can depend on how much selenium is present in the soil they're grown in.

This may partly explain why some studies have shown selenium is in short supply in vegetarian diets, while other studies have shown vegetarian diets provide adequate amounts of selenium.

Calcium

Dairy products are a major source of calcium in the diet. Calcium from plant foods isn't so well absorbed. For vegans, calcium-fortified foods such as fortified soya milk may be useful.

Vitamin B12

Vitamin B12 is found predominantly in meat. There are some non-meat dietary sources such as miso and tempeh, but they appear not to be as useful to the body as the B12 found in meat. Only very small amounts of B12 are required, but it's important for vegans to include a reliable source of vitamin B12 in their diet, which could include:

• Fortified yeast extract
• Fortified breakfast cereals
• Fortified soya milk or rice milk
• Fortified soya protein

Well-planned vegetarian diets boost the intake of fibre, and fruit and vegetables, and are generally lower in saturated fat. This dietary pattern helps to reduce the risk of chronic diseases such as cardiovascular disease and some cancers.

Several studies have shown that vegetarians and vegans are more likely to adopt other healthier lifestyle habits, such as being more physically active and not smoking. Together, these various factors help to explain why a vegan or vegetarian lifestyle is often linked to improved health.

Vegetarian diets can meet the nutrient requirements of different groups of the population such as children, pregnant and breastfeeding women, and older people, provided they're well planned.

If you're already a vegetarian or vegan, or are planning to stop eating meat and meat products, it's worth thinking about what foods you need to eat to ensure you have all the nutrients required for good health.

This article was written by the MRC Human Nutrition Research and published in August 2008.