Nutritional Requirements for Adults: Food Supplements


When requirements for specific nutrients cannot be met by diet alone, vitamin or mineral supplements may be recommended. The following groups of people may benefit from vitamin and mineral supplements, and should discuss their personal needs with a doctor or qualified nutritionist. Pregnant women, in particular, should always check with their healthcare practitioner before taking any supplements.


Menstruating women

Teenage girls and adult women who have heavy periods may benefit from additional iron, but this should be prescribed by a doctor.

Excessive supplementation of iron may cause diarrhoea or constipation.


Women taking oral contraceptives

Taking oral contraceptives may deplete levels of vitamin C and B vitamins, including folic acid.

These vitamins are usually included in multivitamin preparations.


Pregnant women

Women who are pregnant, or planning to become pregnant, are advised to take a daily 400mcg dose of folic acid (also known as folate) to reduce the baby’s risk of spina bifida.

Supplementation should continue up to the 12th week of pregnancy. Pregnant women should seek their doctor’s advice before taking any form of supplement or medication.


Heavy drinkers

Too much alcohol interferes with the absorption of nutrients from food and depletes the body’s supply of B-complex vitamins and vitamin C, as well as interfering with the absorption of zinc, magnesium, potassium and calcium.

A heavy drinker would need to take six times the RDA of vitamin C to achieve the same vitamin C blood-level as a non-drinker.



Cigarette smokers have an increased requirement for vitamin C because they process this vitamin at a higher rate than non-smokers. The need for B-complex vitamins is also increased.

Smoking tends to deaden the senses of taste and smell and also speeds up the metabolism so a smoker may eat less food and therefore obtain insufficient nutrients. Some people have found that switching to e-cigs immediately improves health as less toxins are taken into the body.


People with hereditary risk

People with a family history of degenerative disease, such as heart disease, should consider taking antioxidant supplements containing vitamins C, E and betacarotene.

Antioxidant supplements help the body to fight the free radicals thought to be a contributing factor in degenerative diseases.


Vegans and vegetarians

Depending on the balance of foods they eat, vegans and some vegetarians may be deficient in vitamin B12 because it occurs mainly in animal products.

Before supplementing this vitamin, vegetarians and vegans should check that the product does not contain animal-based lubricants.


Faddy eaters

People who skip meals, eat erratically or rely on fast food may have a large intake of fats and carbohydrates (fast foods typically contain both in abundance) and a small intake of vitamins and minerals. People who follow restricted or ‘starvation’ diets in order to lose weight may also be deficient in certain vitamins and minerals.

Faddy eaters should consider taking a multivitamin and mineral supplement. Teenagers are often faddy eaters and may not eat balanced meals.


Housebound people

People whose skin is rarely exposed to sunlight should seek advice about taking a vitamin D supplement (this vitamin is made in the body by the action of sunlight on the skin).

An excess of vitamin D can affect the heart, lungs and kidneys; moderately high intake over a long period of time may also increase the risk of atherosclerosis. Seek medical advice before supplementing.


Elderly people

Once a person has moved into later life, somewhere about the age of 60, her body has a reduced ability to absorb nutrients from the diet, and a multivitamin and mineral supplement is a sensible addition to the diet.

Elderly people and anyone else taking medication should consult their healthcare practitioner to ensure that there will be no adverse reaction between their medication and the supplements they plan to take.