Vegetarian and vegan diets are now common everywhere. People choose to eat a vegetarian or vegan diet for a variety of reasons such as cultural, moral or health reasons. In athletes the reason may include meeting increased carbohydrate needs or to assist in weight control. A nutritionally sound vegetarian or vegan diet is possible if enough energy is consumed from a wide variety of foods. However, an athlete who consumes a poorly planned vegetarian diet may be at risk from nutritional deficiencies as well as poor physical performance.
Semi-vegetarian diet exludes some but not all groups of animal derived products (for example those who avoid meat but not fish).
Vegan / Strict vegetarian
Strict vegetarian diet excludes all animal derived foods including meat, poultry, fish, eggs, and dairy products. An athlete, without consultation from a dietician, should not attempt a vegan diet, especially young children and adolescents as this could have health risks.
You are unlikely to be deficient in protein if you include dairy-based products and/or eggs in your diet both frequently and in sufficient quantities. If you are an athlete you may require up to 150% more protein than the amount recommended for non-athletes. However, this increased quite target is often met easily as athletes do eat more. You are at greatest risk of inadequate protein intake if you are growing or consume lower quality proteins (i.e plant proteins). Plant proteins have lower digestibility, lower energy content and lower protein quality than meat proteins and therefore athletes and non-athletes may have to increase their protein intake to take account of this lower digestibility of plant proteins.
Ensuring a Balance of Proteins
There are millions of different proteins but all are built from the same twenty amino acids - the basic building blocks. The sequence of the amino acids determines the protein and its function. Our bodies can make amino acids although there are eight amino acids ("essential amino acids") our body can't make and must be supplied in our diets. Plant foods do not contain all the essential amino acids needed by humans - for this reason plant proteins are often described as providing lower protein quality than animal proteins. Animal proteins such as meat and fish have all the essential amino acids and are then described as high quality proteins. It is therefore important to eat a range of plant protein sources to obtain the different amino acids to ensure your body has all its requirements.
For example, cereals (bread, rice and pasta) are low in an essential amino acid called lysine whilst legumes (beans) are low in a another amino acid but by combining them (beans on toast, tortilla and beans) the "cocktail" can provide a mixture of amino acids similar to that of a complete protein found in animal products. It was once thought that a vegetarian should combine plant proteins in each meal; it is now agreed that amino acids needs to be balanced over a period of days rather than hours.
Athletes in Intense Training
If you wish to maximise your recovery then your post exercise meal should include mainly carbohydrate but also some protein. This is because some amino acids (though not all) boost the levels of insulin in the blood resulting in quicker clearance of the blood glucose (from the carbohydrate intake) and allowing a faster rate of muscle glycogen recovery.
Plant protein sources: eggs, fish, legumes, peanut butter, milk, nuts, soyabean products (e.g. tofu), cheese, yoghurt.
Vegetarian athletes are at more risk of iron deficient anaemia than non-vegetarian athletes who eat red meat. In terms of quantity, red meat is a fairly average source of iron but the quality of iron is far superior to that found in plant sources. The main risks groups for iron deficiency are adolescent males and females, vegans, vegetarian athletes and adult female endurance athletes. Coaches should be aware that underlying iron deficiencies can be noticeable in athletes as they become more lethargic and their performance reduces.
Sources of Iron
There are two types of iron: heme iron and non-heme iron. Heme iron is found in meat, fish and poultry and is well absorbed by our bodies. Non-heme iron is found in some vegetables, cereals, pulses, beans and fruit. It is poorly absorbed but when taken with vitamin C or heme iron, absorption will increase significantly. Soyabean and diary products are poor sources of iron, so vegetarians should include other non-heme iron sources in their diets daily through: dark green leafy vegetables, fortified breakfast cereals, dried fruits (dates, apricots, prunes), kale, blackstrap molasses, beans, tofu.
Strategies to meet iron needs
Calcium requirements are highest during childhood and adolescents (with the exception of women who have just had a child). A combination of inadequate calcium intake and amenorrhoea in young children and young women has raised concerns about osteoporosis. Calcium interferes with the absorption of iron, but calcium and iron are both essential nutrients. To overcome this, increase your iron intake to increase the opportunity for uptake. Females who take both an iron and calcium supplement should take the iron supplement with meals (i.e. at breakfast with orange juice to enhance absorption) and avoid calcium supplements with meals (i.e. take these before bed).
Sources of calcium
Vegetarian foods rich in calcium: leafy greens (such as spinach and broccoli), milk, cheese, yoghurt, fish (sardines, and canned salmon), new calcium-fortified orange juices, fortified bread, breakfast cereals, soyabean curd (tofu) but only if made by calcium carbonate (check food label).
Strategies to meet calcium needs Eat at least three servings of dairy foods a day for example milk in cereal, yoghurt, cheese in a sandwich (if you are growing, pregnant or breast feeding increase to 4-5 portions per day). If you do not have regular menstrual cycles you may require extra calcium, seek advice about this from your doctor or, if available, sports medicine doctor. If you are a vegan or unable to eat diary products, include products such as fortified soya or other fortified products, and seek advice about using mineral supplements correctly.
Vitamin B12 deficiency is very uncommon. However, it can develop in strict vegans as vitamin B12 is only found in meat or food derived from animal products, such as dairy products and eggs. No active form of vitamin B12 is found naturally in plant foods (and that includes soya products). Therefore individuals following a vegan diet should include a fortified source of vitamin B12 in the diet such as soyabean milk fortified with vitamin B12 or take a vitamin B12 supplement. However, if you eat dairy products and eggs they will provide you with sufficient amounts of vitamin B12. The current recommended nutrient intake (RNI) is adequate for all requirements apart from cases of malabsorption (impaired absorption of nutrients).
It has been reported that vegetarians have a lower zinc status than non-vegetarians. This may be due to the fact that cereals, legumes, nuts soya products and eggs are secondary sources of zinc. However there is no indication that vegetarian athletes or non-athletes need to include zinc supplements in the diet. The best sources of zinc are crab, shrimps and oysters.
Run The Planet thanks ScottishSport.co.uk (www.scottishsport.co.uk) for the permission to reprint the article "The Vegetarian Athlete" by Ruth McKean, Sports Nutritionist. Text copyright © 2002 by ScottishSport.co.uk. All rights reserved.