What are the possible health benefits of a vegetarian diet? On the downside might you be missing out on important nutrients?
What healthy nutrients does a vegetarian diet contain?
Vegetables and fruits contain fibre, as well as vitamins such as A, C and E. Eating more fruit and vegetables is associated with a lower risk of death from all causes, in particular cardiovascular (e.g. heart attack and stroke). That’s according to a review of 16 different studies published in the BMJ in 2014.
Pulses are a good source of protein, fibre and minerals such as iron, zinc and magnesium.
Wholegrain products contain vitamin B, potassium, magnesium and zinc. They may reduce mortality in people with type 2 diabetes.
Nuts and seeds are rich sources of Vitamin E and essential fatty acids. The U.S. Food and Drug Administration has granted tree nuts a qualified health claim for cardiovascular disease risk reduction.
Is what a vegetarian diet excludes also important?
The UK Department of Health has advised those consuming large quantities of red and processed meat to cut back – as this probably increases the risk of bowel cancer.
Cutting out saturated animal fat may have other health benefits, as saturated fats are believed to increase the risk of cardiovascular disease. However, this is currently being debated. Some countries like France consume quite a lot of saturated fat but have low levels of cardiovascular disease. They also consume quite a lot of fruit and vegetables though, which may be protective.
According to the Harvard School of Public Health, on balance fish and moderate egg consumption (provided the eggs are stored and cooked properly) can form part of a healthy diet. However, its Healthy Eating Plate suggests that we limit dairy products like milk, cheese and butter.
What is the evidence for health benefits?
Metabolic disorders are factors believed to increase the risk of heart conditions, stroke and diabetes. They include high blood pressure, high blood glucose levels, high LDL (‘bad’) cholesterol, and being overweight. A US study found that vegetarians had a lower incidence of metabolic disorders.
Research from the USA also suggests that vegetarian diets are associated with lower deaths from all causes - particularly from heart attack and stroke, kidney failure and diabetes. These reductions were larger and more significant in men than in women. This research aimed to take account of other potential factors, like smoking, alcohol, exercise, education and sleep – to specifically identify the effect of diet.
However a European Study published in 2009 found no difference in the death rates of vegetarians and non vegetarians in Britain. It did note though that death rates from both groups studied were low compared with national rates. This suggests that further research is needed.
Are all vegetarian diets the same?
There are five main types of vegetarian diet:
The strictest is vegan i.e no food of any kind which has animal origin, including honey. Some vegetarians eat dairy products (lacto – vegetarians), some eat eggs (ovo-vegetarians) and some eat both (lacto – ovo vegetarians). Pescetarians eat the widest range i. e fish, eggs and dairy products - but not poultry or meat.
These different vegetarian diets have different nutritional consequences (see below):
Are there possible deficiencies in a vegetarian diet?
Yes. Animal protein (from eggs, dairy products, fish and meat) tends to provide all the amino acids we need. In contrast each type of plant based protein (from pulses, seeds, nuts, grains, fruit and vegetables) typically lacks one or more of the essential amino acids.
This is more of an issue with a vegan diet. It is less of an issue with vegetarian diets that allow other sources of protein, like eggs and dairy products. The stricter the vegetarian diet the more important it is to have a good mix of different types of plant protein, to optimise nutrient intake. For example beans on toast provides pulses (beans) and cereals (bread). Adding a glass of soya milk, some nuts and a banana would add soya, nuts and fruit i.e. three additional and different types of plant based protein. Soya and quinoa are said to be the best plant based sources of essential amino acids.
The main nutrients vegetarians and vegans need to ensure they get enough of are iron, selenium, vitamin B12 and omega-3 fatty acids. Potential sources are:
- Pulses, green vegetables, wholemeal bread, dried fruit, nuts, seeds and eggs (for iron) – ideally with fruit, to help increase the absorption of iron.
- Brazil nuts, cashew nuts and pecans (for selenium)
- Yeast extract and some fortified breakfast cereals (for Vitamin B12)
- Tofu, flaxseed, eggs, walnuts and walnut oil (for omega – 3)
Vegetarian diets from around the world provide interesting alternatives – like tortillas, beans, avocado and salsa (from Mexico) or Chana Masala (chickpeas stewed with onions, tomatoes and spices and eaten with rice), from India.
- Vegetables, fruit, pulses, whole grains, nuts and seeds contain a range of health enhancing nutrients.
- Some (but not all) research suggests a vegetarian diet reduces the risk of heart attack, stroke and diabetes – and the risk of becoming overweight.
- However, there are different types of vegetarian diet.
- The stricter the vegetarian diet the more important it is to eat a wide range of sources of plant based protein to get all the nutrients needed (which non vegetarians get through meat, fish, eggs and dairy products).
Published 05/06/2011, Reviewed by Natnaree Kaewhin, September 2014
Next Review date August 2017