Vegetarians have a lower risk of developing heart disease, some types of cancer, high blood pressure, stroke, diabetes and obesity. However, vegetarian diets must be planned carefully to avoid missing out on important nutrients.

Some vegetarians eat dairy foods or eggs, and others eat white meats (chicken or fish). However, 'vegans' avoid all animal foods and are most at-risk of nutritional deficiencies, especially in pregnancy or childhood. Nutrients of most concern are:

Iron. As red meat is the richest source of iron, people who do not eat meat (particularly menstruating women) should boost iron intake from other foods. These include iron-fortified cereals, leafy green vegetables (e.g. spinach, broccoli), beans, lentils, nuts and wholegrain bread. Iron is best absorbed if eaten with food containing vitamin C, such as orange juice or tomatoes, and if not drunk with tea or coffee at the same meal.

Calcium. Vegetarians who do not eat dairy foods can get extra calcium from calcium-enriched soy drinks, canned fish with edible bones, almonds and tofu.

Zinc. Animal foods are the richest source of zinc. However, zinc is also found in seeds and nuts, wholegrain cereals and breads.

Vitamin B12. If you don't eat meat, dairy products or eggs, have B12-fortified soy milk or cereals. Ask your doctor if your diet is adequate.