Useful supplements

The Ministry of Health says most people in New Zealand can get all the nutrients they need from their food. Professor Jim Mann of the Department of Human Nutrition at Otago University says millions of dollars are wasted on dietary supplements each year. We agree with both points.

These are the supplements with well-established health benefits, and the circumstances in which they should be taken. It's a small list.

Folate

(also called folic acid) is a B vitamin, important for women planning or in the early stages of a pregnancy. There is evidence it reduces the incidence of neural tube (birth) defects.

The Ministry of Health recommends women take a 0.8mg supplement of folate four weeks before they conceive and for the first 12 weeks of the pregnancy.

They should also increase the folate in their diet by eating fruit and vegetables and wholegrain breads and cereals. Some breakfast cereals and some fruit juices are fortified with folate - this will be stated on the label.

New Zealand and Australian food ministries have decided it will be compulsory to add folate to some bread. Mandatory fortification on its own won't increase intake to the levels required. Those planning a pregnancy will still need to take a supplement.

Vitamin B12

is only found in animal products. The richest sources are liver and kidney. It's also found in other meats and in lesser amounts in milk and milk products.

Vegetarians, and especially vegans, are at risk of vitamin B12 deficiency.

Vitamin D

aids in the absorption of calcium and is important for bone health. Most of us get enough vitamin D from exposure to sunlight. The only people who may need a top-up are those who rarely get outside.

Margarine, eggs, butter and oily fish like salmon are good sources of vitamin D.

Iron

deficiency may result in anaemia. This is a medical condition and should be properly diagnosed by a doctor.

Supplements are necessary when there is evidence of iron-deficiency anaemia, or when women have high menstrual losses, or are pregnant and have low iron stores.

Vegetarians may also have low iron stores. The iron in meat, poultry and seafood (called "haem" iron) is more easily absorbed than the non-haem iron in vegetables.

Calcium

is needed for strong bones and is especially important for growing children and women after menopause. Doctors sometimes recommend supplements to people at risk, especially frail, older women.

Milk and milk products are good sources of calcium. You can also keep up your calcium levels from non-dairy sources like green vegetables, wholegrain cereals and breads, canned fish with bones, beans, nuts and calcium-fortified soy drinks.