Vegetarian diet - a fresh look

The key to obtaining health benefits from a vegetarian diet is good knowledge and planning.

Seven out of 10 Australians are now eating more plant-based foods, largely in the belief that eating less meat and more plant foods improves overall health – a belief that is now supported by evidence.

Health benefits
A vegetarian diet can confer health benefits such as decreased risk of chronic diseases (responsible for 63% of worldwide mortality). This finding coincides with new concerns about a correlation between a high red meat diet and colorectal cancer.

Current evidence suggests strict protein combining is unnecessary as the body is able to store reserves of amino acids which form essential proteins. Because most Australians eat more protein than they require, vegetarians who generally eat less protein still meet their nutritional requirements. A nutrient-rich diet containing a variety of plant foods will contribute adequate amounts of protein to the diet, provided energy intake is adequate.

Vegetarians should plan to include a variety of protein-rich foods each day, with a particular emphasis on adequate intake of iron, zinc, calcium and vitamin B₁₂ (from animal sources).

Vegetarians are not at any greater risk of iron deficiency anaemia than non-­vegetarians if they eat a varied, well balanced diet. People with low iron stores or higher physiological need for iron will tend to absorb more iron and excrete less.

Non-haem iron bioavailability is dependent on enhancers and inhibitors in the diet. Vitamin C is a powerful enhancer, while phytic acid (legumes, wholegrain cereals) and polyphenols in drinks (tea and coffee) are inhibitors. Including a wide variety of foods is likely to cancel out the effects of these enhancers and inhibitors.

Health concerns
The key to obtaining health benefits from a vegetarian diet is good knowledge and planning. Experimentation with a vegetarian diet frequently begins in teenage years when knowledge of food composition and nutrition is limited. This can result in elimination of the major protein groups and a failure to replace these with nutritious alternatives, resulting in poor choices of vegetarian meal plans which may then compromise health. Monitoring intake in young vegetarians will maximise health benefits.

Conclusion
Vegetarians who eat a nutrient-rich diet can meet their protein requirements and are not at any greater risk of iron deficiency anaemia than non-vegetarians.

A well planned vegetarian diet contributes health benefits such as weight management and reduction in chronic disease risk.

Vegans may require vitamin B₁₂ and long-chain omega-3 fatty acid supplementation.                

Variations on a vegetarian diet

• VEGETARIAN: Does not consume meat, poultry, fish or seafood
• VEGAN: Does not consume any animal products or by-products
• SEMI-VEGETARIAN: Consumes dairy products, eggs, chicken and fish, but does not consume other animal flesh
• LACTO-OVO-VEGETARIAN (LOV): Does not consume meat, poultry, fish or seafood, but does consume eggs and milk. This is the largest group of vegetarians 
• OVO-VEGETARIAN: Consumes eggs
• LACTO-VEGETARIAN: Consumes milk
• FLEXITARIAN: Eats fish occasionally
• VEGIVORE: Adds meat as a condiment

Eight important points to know about a vegetarian diet

1. Vegetarian diets do provide health benefits such as reduced risk of many chronic diseases, e.g. diabetes and heart disease.
2. Requirements for most key nutrients (except vitamin D, long-chain omega-3 fatty acids and iron during pregnancy) can be met across the life cycle by well planned, plant-based, nutrient-dense, lacto-ovo-vegetarian diets.
3. Protein needs can be adequately met from a varied plant-based diet that includes legumes, soy products, grains, nuts and seeds.
4. Vitamin D deficiency levels in vegetarians are comparable to non-vegetarians; important dietary sources are margarine, eggs, soy milk fortified with vitamin D, and oily fish.
5. Vegetarian diets that exclude fish need to include adequate amounts of short-chain n-3 PUFAs found in chia seeds, flaxseeds and walnuts. Additional supplementation may also be required.
6. B₁₂: Good sources of vitamin B₁₂ include milk, fortified soy milk, yoghurt, cheese, egg and fortified yeast spread.
7. Zinc: Concerns about phytate as an inhibitor of zinc absorption are minimised by modern food processing methods. The body can adapt to different levels of zinc intake by adjusting absorption rate relative to the amount of endogenous zinc lost. Good sources are nuts, seeds, legumes and dairy.
8. Iron: Cereal products are the main source of dietary iron for all Australians (a bigger contributor than meat). Uptake is increased up to sixfold when combined with vitamin C-rich foods. Vegetarians with lower stores of iron or higher physiological need will absorb more iron and excrete less iron. Good sources are cereals, legumes, nuts, seeds and fortified foods.

Catherine Lombard, B.Sc, Grad Dip Diet, PhDManager Healthy Lifestyle Program , Women’s Public Health Research , Monash University.

Jean Hailes for Women’s Health is a national, not-for-profit organisation focusing on clinical care, innovative research and practical educational opportunities for health professionals and women.

http://www.jeanhailes.org.au/Reference: MJA Open 2012; 1 Suppl 2