What is a vegan diet?

The idea

A vegan diet avoids all animal foods, including meat, fish, chicken, eggs, dairy products and honey. Most people follow such a diet for philosophical reasons. Many do not like killing animals and many object to keeping any animals for the production of food.

The science

As this is a philosophical question, the main concerns revolve around whether a vegan diet can provide the nutrients we need. If well chosen, a vegan diet can be nutritionally adequate, with the exception of vitamin B12 which is found mainly in animal foods. Vitamin B12 is essential for making red blood cells and also is a vital component of nerve cells. A deficiency may take years to develop but the effects are major and a deficiency may be irreversible. Mushrooms contain a small amount of vitamin B12, but even regular consumption of mushrooms would provide only about 5% of the body’s needs. Substances with some similarity to vitamin B12 are found in comfrey and spirulina, but these can’t be used by the body and these foods cannot be regarded as a source of vitamin B12.

Research shows that a vegetarian diet (which is different from a vegan diet because it may include dairy products and eggs) is linked with a lower risk of obesity, heart disease, type 2 diabetes and bowel cancer. Due to a lack of research data, we do not know whether the same benefits occur in vegans, but the benefits are expected providing a variety of plant foods are included.

How to ensure an adequate vegan diet

• Protein is easily supplied by legumes, tofu, soy drinks, grains, nuts and seeds. As long as a variety and sufficient quantity of these foods are consumed, protein needs will be met. The old idea that certain foods needed to be consumed together to supply enough essential amino acids has been superseded by newer research that shows the body can easily meet its needs as long as a variety of foods is consumed over the day.
• Iron can be supplied by legumes, tofu, wholegrains and iron fortified cereals, vegetables, nuts and seeds. In general, there is no more iron deficiency among vegans than among meat eaters – as long as a variety of plant foods is consumed. However, pregnant women should ask their doctor to check their iron levels in case a supplement is required.
• Zinc is supplied by legumes, wholegrains, nuts and seeds. These foods also contain substances called phytates which may hinder zinc absorption. Soaking legumes, adding yeast to breads and roasting nuts enhances zinc absorption and most vegans should have no problem absorbing ample quantities.
• Calcium can be supplied by almonds, fortified soy, rice or oat milks and tofu that is set with a calcium salt (check the label).
• Other minerals and vitamins are easily supplied from a variety of fruits, vegetables, legumes, grains, nuts and seeds.

Watch out for

Vitamin B12. Take a vitamin B12 supplement or choose sufficient quantities of foods that have been fortified with this vitamin. Some soy drinks and meat alternatives are possibilities, but check the label. The recommended dietary intake for adults is 2.4 micrograms/day.

Omega 3 fats. These polyunsaturated fats come in two types: those in plant foods such as walnuts, linseeds, chia seeds and canola and some longer chain omega 3s found in fish and other seafood and grass-fed meat. The plant-based omega 3s have to be converted to the longer chain omega 3s and this reaction requires a particular enzyme. A diet that is high in vegetable oils and spreads such as sunflower, safflower, corn, grapeseed may ‘use up’ the enzyme. Better choices in a vegan diet are extra virgin olive, avocado, canola oils or walnut oils and spreads made from them.

Visit our vegan recipe collection.

Source

Taste.com.au — January 2013

Author

Dr Rosemary Stanton