We know vitamins and minerals are essential building blocks for growth, development and a healthy immune system, but each of these micronutrients has a different function and the dangers posed by certain deficiencies are diverse – so which do you really need in your diet and when is the right time for you to use supplementation?
Since every individual is physiologically and environmentally unique, there's no clear-cut answer. A balanced diet supplemented by a daily multivitamin should be sufficient to keep most people healthy, but individuals lacking in a particular nutrient may need a little extra help. Vitamins A, D, E and K require fat to be absorbed, so deficiencies may develop in people who follow extremely low-fat diets, while children, pregnant women and the elderly are more susceptible to certain vitamin and mineral deficits.
It's vital to ensure that you're getting enough of all the nutrients and take a supplement if you're not, says dietician Elienne Horwitz, but it's also important to stick to the recommended dietary allowance (RDA) for individual vitamins and minerals. "Stay away from mega-doses – in huge amounts, they act more like drugs than nutritional supplements and are potentially harmful," she warns.
NOTE: All RDAs here are applicable to adults – childhood doses may be much lower in certain cases.
Vitamin A is known for its vision-honing and immunity-enhancing properties. When selecting a Vitamin A supplement, choose beta carotene over retinoic acid or retinol, as the latter can cause brittle bones if taken in excess. Overdosing on Vitamin A can cause dryness of the lips, skin, hair, nose and eyes – or in extreme cases, liver disease, so be sure to never exceed the absolute required daily dosage.
RDA: men 900mcg/day, women 700mcg/day
All B vitamins play a role in the metabolism of cells, maintain healthy hair, skin and muscles, support the immune system, promote cell development and division, and contribute to psychological wellbeing. Certain B vitamins are also thought to ward off fatigue, although research in these areas is ongoing*. (see sidebar)
RDA: B1: men 1.2mg/day, women 1.1mg/day, B2: men 1.3mg/day, women 1.1mg/day, B3: men 16mg, women 14mg, B6: 1 - 1.7mg/day, depending on age, B9: 400mcg/day, B12: 2.4mcg/day
Vitamin C protects against infection and supplementation is particularly important during times of emotional and physical stress, when the body uses it more quickly. Despite its popularity as a treatment for the common cold, research regarding its efficacy has produced inconclusive results and most experts believe it alleviates but not eliminates symptoms. Vitamin C is also necessary for the absorption of iron, so not getting enough can indirectly cause iron deficiency or anaemia. Intake of Vitamin C (over 2 000mg/day) can cause gastrointestinal disorders and kidney stones.
RDA: men 90mg/day, women 75mg/day
Key to healthy bone formation, calcium is a mineral you don't want to be missing out on, so you should take a supplement if your dietary intake is insufficient, says dietician Elienne Horwitz. A deficiency can put you at risk for developing osteoporosis, a degenerative bone disease, and researchers suspect it may also play a role in causing colon cancer and hypertension. Although, you don’t want to overdose on the stuff either – taking calcium in huge doses can cause the body’s soft tissues to calcify, which can be potentially lethal in the case of the kidneys.
RDA: men 1 000mg, women 1 000 - 1 300mg
One of the harder vitamins to get through diet alone, Vitamin D facilitates the absorption of calcium and is essential for the development of healthy bones. It is found in only a handful of foods, including fatty fish and fish oils, and the only other natural way to bump up your levels is exposure to direct sunlight. In children, a Vitamin D deficiency can cause rickets - a skeletal disease that causes distinctive bow-shaped legs and a "cowboy" gait. In adults, too little Vitamin D can cause weak muscles and bones symptomatic of a degenerative disease called osteomalacia. Low Vitamin D levels have also been linked to depression and several studies have shown supplementation to improve mood in depressed patients.
Vitamin E has antioxidant properties and protects the body against free radicals, associated with premature ageing of the tissues, cells and internal organs. For this reason, it helps to keep the skin healthy, supple and youthful and may even be instrumental in warding off more serious age-related illnesses, such as cancer, cardiac disease, stroke and dementia. Signs of a Vitamin E deficiency include visual disturbances, muscle weakness and changes in balance.
The active ingredient in many toothpastes and mouthwashes, fluoride is best known for its role in the formation and maintenance of healthy tooth enamel. Be careful not to overdo it though – too much fluoride during childhood can cause unattractive discolouration and mottling of teeth in later life.
RDA: 1.5 - 4mg
If you're feeling washed out and sluggish, you may be suffering from anaemia, a condition associated with iron deficiency. Iron's most vital function is to transport oxygen to the cells, which is why a a shortage can bring on fatigue and lethargy – the body's cells are literally suffocating. In more severe cases, anaemia can also wreak havoc with the immune system, red blood cell functioning and thought processes.
RDA: 8mg/day (but 27mg/day in pregnant women)
Vitamin K plays an important role in blood clotting and preventing haemorrhage. People at risk for deep vein thrombosis should steer well clear of Vitamin K supplements, as they may exacerbate the problem.
RDA: men 120mcg, women 90mcg
Trouble sleeping? You might not be getting enough magnesium. It is a natural muscle relaxant and a deficiency can lead to tremors, muscle spasms, loss of appetite, nausea and vomiting, personality changes and heart disease. It's also important for bone density.
RDA: men 420mg/day, women 320mg/day
Zinc is involved in cell repair, so take it when you have an open wound, when feeling under the weather, or to boost immunity when you feel a bug coming on. Zinc is essential for promoting healthy growth and plays a role in reproductive health: missing out on this mineral can stunt growth, producing vertically challenged adults, and cause hypogonadism in men – a disorder linked to low testosterone and sperm count.
RDA: men 11mg/day, women 8mg/day
When you need them most...
Deficiencies of B9 (folate) during pregnancy have been linked to birth defects. Pregnant women are also at risk for iron deficiency, as the amount of blood in the body increases and needs more iron to transport oxygen to additional cells. Iron is also vital for the healthy development of the baby and placenta – iron deficiency anaemia has been associated with low birth weight and, in severe cases, infant death. While Vitamin A is also important during pregnancy, be sure to limit your intake to the RDA – high doses have been linked to miscarriage and deformities.
A national survey found that one in two SA children aged one to nine receive less than 50 percent of the RDA of Vitamins A, C, B2, B3, B9, calcium, iron and zinc. Vitamin A is vital for effective eyesight, Vitamins B2, B3 and B9 for metabolism and strong immunity, Vitamin D and calcium for healthy bones, zinc for growth, and iron for concentration and energy.
Research has found that higher levels of Vitamin B, Vitamin C, Vitamin D and Vitamin E are linked to more efficient cognitive functioning in senior citizens. Getting enough magnesium and calcium should also be a priority in later life to protect against weak, brittle bones.