Vitamin A is a fat soluble vitamin which is stored in the liver. Found in animal foods and converted from beta-carotene in plant foods, vitamin A health benefits include: healthy vision, gene expression, reproduction, embryonic development, red blood cell production, and immune function.

Deficiency is rare in Canada, but common in developing countries due to malnutrition. It causes night blindness, dry eyes and skin, and impaired growth.

Drugs that deplete vitamin A include:  cholestyramine, colestipol, mineral oil, and neomycin.

Vitamin A supplements from beta carotene should be avoided by those at risk of lung cancer (smokers) since a number of large scale studies have shown an increase in lung cancer rates when smokers consumer beta carotene in a supplement.

Those with liver toxicity (alcoholics, liver disease) should also avoid beat carotene supplements since beta carotene is stored in the liver.

Doses greater than 10,000 IU daily should be avoided by pregnant women due to the risk of birth defects.   Supplements of vitamin A beyond what is provided in a multivitamin are not recommended due to risk of toxicity. To avoid this risk, choose a multivitamin that contains beta-carotene, which is converted to vitamin A in the liver, but is not associated with health risks. Eating a lot of beta-carotene from foods can make your skin look yellow, because  beta-carotene (which is a yellow-orange pigment)is stored in the cells under our skin. This may look odd but it is not harmful to your health.

Foods that provide vitamin A health benefits include: liver, dairy products, and oily fish (Beta-carotene is found in orange and green vegetables and fruit).

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Zinc is often found in multivitamins and prenatal supplements.  It is used in our bodies to support immune function, reduce severity and duration of the common cold, and delay the progression of macular degeneration. It is also involved in numerous enzyme reactions and is required for growth and development, immune and neurological function, reproduction and regulation of genes and to stabilize the structure of proteins and cell membranes.

Although a severe zinc deficiency is rare, except in those with a genetic disorder, severe malnutrition or malabsorption, severe burns, or chronic diarrhea, marginal deficiencies are common in malnourished people, vegetarians, pregnant women, the elderly, and those with celiac disease, Crohn’s disease, colitis, and sickle cell anemia.

Zinc deficiency symptoms include impaired growth and development, skin rashes, severe diarrhea, immune system deficiencies, impaired wound healing, poor appetite, impaired taste sensation, night blindness, clouding of the corneas, and behavioural disturbances.

Some people that are on prescription drugs may deplete their store of zinc. Drugs that deplete zinc include: diuretics, anticonvulsants, iron supplements, penicillamine, ACE-inhibitor drugs, acid-reducing drugs, and oral contraceptives.

Zinc supplements can reduce copper levels, so look for a multivitamin that contains copper as well as zinc. Zinc supplements can also reduce absorption of antibiotics (tetracycline and quinolones), so separate intake of zinc supplements from these products by two hours. Since the average zinc intake is below the RDA and many conditions and drugs deplete zinc levels, a supplement should be considered. Most multivitamin and mineral complexes provide at least the RDA for zinc.

Foods that are rich in zinc include: red meat, shellfish, eggs, whole grains, and fortified cereals. Too much zinc can cause abdominal pain, diarrhea, nausea and vomiting. High dosages of zinc supplements may reduce copper levels.

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