Clare Collins
There are many reasons people go vegan, from wanting to be healthier, to reducing their environmental footprint, to concerns about animal welfare.
No matter what the reason, many people find it difficult to meet the nutrient intake targets for specific vitamins and minerals while on a vegan diet. These include vitamin B12, iron, calcium, and iodine.
VITAMIN B12: Vitamin B12, or cobalamin, is essential for making red blood cells, DNA (your genetic code), fatty acids located in myelin (which insulate nerves), and some neurotransmitters needed for brain function. It is stored in the liver, so a deficiency probably won’t happen in adults in the short term.
Symptoms of vitamin B12 deficiency include tiredness, lethargy, low exercise tolerance, light-headedness, rapid heart rate or palpitations, bruising and bleeding easily, weight loss, impotence, bowel or bladder changes and bleeding gums.
Other symptoms related to the nervous system include a loss of sensation in the hands or feet, problems related to movement, brain changes ranging from memory loss to mood changes or dementia, visual disturbances, and impaired bowel and bladder control.
Vitamin B12 is abundant in animal foods including meat, milk and dairy products. For vegans, plant sources of vitamin B12 include some algae and plants exposed to bacterial action or contaminated by soil or insects. While traces of vitamin B12 analogues can be found in some mushrooms, nori or fermented soy beans, more reliable sources include vitamin B12-supplemented soy or nut “milks”, or meat substitutes. Check the nutrition information panel on the label for the B12 content. Crystalline vitamin B12 added to these products can boost the B12’s absorption rate.
CALCIUM: Calcium is needed to develop and maintain skeleton bones, and is stored in teeth and bones. It is also essential for heart, muscle & nerve function.
Low calcium intakes are associated with osteoporosis or “brittle bones” and a higher risk of bone fractures.
A bone scan is used to measure bone density, with osteoporosis diagnosed when bone density is low.
Both low calcium and low vitamin D levels increase risk of osteoporosis.
Although the richest sources of calcium are milk and milk-based foods, vegans can get calcium from tofu or bean curd, some fortified soy or nut beverages, nuts, seeds, legumes and cereals.
Calcium needs can be higher for vegans and vegetarians due to the relatively high oxalic acid content of foods such as spinach, rhubarb, beans, and the high phytic acid content of seeds, nuts, grains, some raw beans, and soy products. These specific acids can lower the calcium absorption from these foods by 10-50%.
In a study of calcium intakes of 1,475 adults , vegans were below national recommendations and had lower calcium intakes compared with vegetarians, semi-vegetarians, pesco-vegetarians, and omnivores.
IODINE: Iodine is needed to make thyroxine, a thyroid hormone used in normal growth, regulation of metabolic rate, and development of the central nervous system. Iodine is concentrated in the thyroid gland.
Iodine deficiency can lead to the enlargement of the thyroid gland, a goitre, or hypothyroidism.
Symptoms of hypothyroidism include lethargy, tiredness, muscular weakness, feeling cold, difficulty concentrating, poor memory, weight gain, depression, facial puffiness, hair loss, dry skin, constipation etc.
The iodine content of food depends on the iodine content of plants, which in turn depends on soil iodine content. When soil content is low, iodine may need to be supplemented.
Major sources of iodine are seafood, dairy products, and eggs. For vegans, iodised salt, commercial bread made using iodised salt, fortified soy or nut milks and seaweed are important.
Substances called goitrogens, which are found in brassica vegetables “ including cabbage, broccoli and Brussels sprouts, sweet potato and maize “ can interfere with thyroid hormones.
IRON: Iron is needed to make haemoglobin in red blood cells, which carries oxygen around your body.
Iron is also needed for the production of energy in muscles, and for concentration and healthy immune system.
Not having enough iron leads to iron deficiency, and is associated with reduced work capacity, impaired brain function, lower immunity, and delayed development in infants.
The first stage of iron deficiency is referred to as low iron stores and your doctor may refer you for a blood test to check your iron status.
The biggest contributors to iron intake are wholegrain cereals, meats, chicken, and fish. The amount of iron absorbed from food depends on a person’s iron status (with those who are iron-deficient absorbing more), as well as the iron content of the entire meal, and whether iron is haem (from animal foods) or non-haem iron from plant sources such as grains and vegetables.
Long-term vegans will also need to keep an eye on levels of vitamin D, omega-3 fat and protein.
A good strategy is to check with your GP to review your health and well-being, and an accredited practising dietitian can check whether you’re getting all the nutrients you need.
