There are several kinds of meat-free diets. The most common are:
Lacto-ovo-vegetarian: this describes the majority of vegetarians. Meat, poultry and fish are excluded, but eggs and dairy products are still eaten.
Lacto-vegetarian: Meat, poultry, fish and eggs are excluded; dairy products are still eaten.
Vegan: All animal products are excluded, including meat, poultry, fish, eggs and dairy products.
So what nutrients do animal products provide and what are alternative sources?
Meat, poultry and fish provide a number of nutrients includingprotein, iron and zinc, while dairy products are a source ofcalcium. If you choose not to eat these foods, you should be aware of other sources of these nutrients.
Proteins are made up of building blocks called amino acids, which are used to make enzymes, hormones and antibodies. Proteins also have other functions, for example, to help build bone and hair.
Animal protein is ‘complete’, which means that it contains the nine essential amino acids that can’t be made by the human body. Vegetarians can find this complete protein in eggs and milk.
Plant foods tend not to contain complete proteins, but when eaten together with other plant foods can join forces to create a complete protein profile. Vegans especially should try to mix grains, legumes, seeds, nuts and vegetables in each meal or at least throughout the day. This can be as simple as eating more beans or a chickpea curry with rice.
Iron’s main job is to transport oxygen around the body in red blood cells. Iron deficiency can cause fatigue and apathy, and if severe, can lead to anemia. Women are particularly susceptible to deficiency because their iron requirements are higher than men’s (due to the blood they lose during menstruation).
Iron from meat is more easily absorbed than iron from plants. That said, wholegrains, legumes, green leafy vegetables and dried fruits are also good sources of iron. The citric acid and vitamin C in orange juice increase iron absorption, so vegetarians would be wise to drink a glass with iron-rich foods. On the other hand, tannins in tea reduce absorption, so it’s best to wait half an hour or so after eating before brewing a cup.
Zinc is a major player in the body’s immune system and metabolic processes. Around 50 per cent of zinc in most of the population's diet comes from meat. Plant sources include green leafy vegetables, seeds, pulses and wholegrains.
Omega-3 fatty acids
These powerful anti-inflammatory and anti-clotting oils, most commonly found in oily fish, can help prevent heart disease. Linseed and rapeseed oils are good sources for vegetarians.
Calcium builds bone and teeth and is also involved in muscle contraction. Dairy products are a great source of calcium, but vegans may require other sources such as green leafy vegetables, soya, seeds, nuts and fortified foods like soya milk, flour and cereal.
This nutrient can only be found in animal products; therefore vegans are at risk of deficiency. Vitamin B12 is important for the nervous system and cell production, particularly red blood cells. Some foods such as soya milk, cereals and meat-substitutes are fortified with B12; vegans should try to eat these foods regularly and should also consider supplements.
Health benefits of a meat-free diet
Vegetarians have been shown to have lower rates of heart disease, type II diabetes, constipation and high blood pressure than meat-eaters. They are also likely to be leaner. However, researchers are not sure if this is due to the diet itself or the healthy lifestyle that vegetarians are more likely to follow e.g. not smoking, low alcohol intake and regular exercise.