A vegan diet is one that consists of exclusively plant-derived foods. Vegans don't use or consume any animals (land or sea) or animal products such as milk, eggs, or honey. When eliminating major food groups, there is always a concern that the diet may be deficient in certain nutrients. Two key nutrients that are commonly at risk for deficiency in the diet of vegans are Vitamin B12 and Calcium. As such, it is important to make a concerted effort to include a varied and balanced intake of foods that will ensure an adequate intake of all micro nutrients (vitamins and minerals).
What is Vitamin B12 and why do we need it?
Vitamin B12 is a water-soluble vitamin that helps to maintain many cells in the body with special reference to our blood cells and the cells of our nervous system. It is also required for the manufacture and repair of genetic material in the cells known as DNA. A lack of Vitamin B12 can cause a type of anaemia called megaloblastic anaemia that is characterised by weakness, tiredness or light-headedness as well as nerve problems like numbness or tingling and muscle weakness. The recommended dietary requirement for vitamin B12 is 2.4 mcg daily for those over the age of 14 years.
Vitamin B12 sources in the Vegan diet
As vitamin B12 does not appear in any plant foods, the only way to meet the requirement is from consuming fortified foods or taking a supplement containing vitamin B12. Food fortification is the process of adding micronutrients (essential trace elements and vitamins) to foods when they would not necessarily have contained these nutrients beforehand.
commonly fortified with vitamin B12 are plant based milks (soya milk, rice milk
and almond milk), yoghurts as well as certain fortified breakfast cereals where
Vitamin B12 is added to increase micronutrient levels. For example, a small
portion of 30 g of a fortified breakfast cereal can contain up to 100% of the
daily vitamin B12 requirement. A cup of
soya yoghurt (250ml) can provide 50% of the B12 requirement.
What is Calcium and why do we need it?
Calcium is a vital nutrient for growth and development of bones and teeth which makes it an essential mineral in the diet. The heart, nerves, and blood-clotting systems also require calcium for optimal functioning. The recommended dietary requirement is 1000 mg per day for adults aged 18 years to 50 years. Women over 50 years and men over 70 years should consume 1200 mg daily. Insufficient intakes of calcium can contribute to an increased risk for developing bone related diseases like osteoporosis and osteopenia which causes brittle and fragile bones that can fracture and break easily.
Calcium sources in the Vegan diet
Some foods, such as spinach, contain a high amount of calcium but the calcium is bound to a substance called 'oxalate' which reduces the absorption of the calcium in the gut. As a result, certain plant based calcium sources can be considered less bioavailable which means the body cannot absorb all the calcium present in the food source. Choosing low-oxalate vegetables such as rocket, cabbage and kale are key to ensuring sufficient calcium levels in a strictly vegan and plant based diet.
Calcium is also found in fortified foods such
as plant milks (soya milk, rice milk, almond milk etc.) and foods such as tofu
and fortified bread. Green leafy vegetables, including cabbage, rocket,
watercress, kale, broccoli and parsley are a source of calcium in the vegan
diet as are oranges; kidney beans; chickpeas; and mixed raw nuts and seeds. One
cup of cooked broccoli contains 180 mg of calcium (18% of daily requirements);
50 g of tofu can have approximately 200 mg of calcium and 30g of sesame seeds
have 280 mg of calcium (almost 30% of daily requirements).
From a practical point of view, it is a challenge to select and enjoy an adequate amount of these foods to meet the requirement on a daily basis. To calculate your daily dietary intake of calcium try this calcium calculator http://caltrate.co.za/calciumcalculator. Should your dietary intake be insufficient, it is recommended that adults consider taking a calcium supplement that will provide 500-600mg of elemental calcium.
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