Dietary supplements
Dietary supplements are products designed to give you nutrients that might be missing from your diet. They can also be used to help to manage or treat a health condition. They may also be called food supplements or nutritional supplements.
Types of supplements
Supplements are available in a variety of forms. These include:
- tablets
- capsules
- liquids
- gummies
- powders.
Popular supplements include:
- vitamins such as multivitamins, and vitamins D, C and B12
- minerals such as iron and magnesium
- herbs such as echinacea, St John's wort, turmeric and garlic
- protein powders such as whey protein, pea protein and soy protein
- products such as glucosamine, probiotics, fish oils and ones to support sleep.
When to take dietary supplements
Most people can get all the nutrients they need from eating a wide variety of healthy food and spending time outside in the sun to get vitamin D.
Taking supplements will not protect your health if you have been eating poorly or give you a boost if you are run down. Unless the supplement has been recommended by a healthcare provider it is usually better to spend your money on whole foods that protect your health.
Some supplements might be useful for some people. These include:
- an iron supplement if you have low iron or iron deficiency anaemia
- folic acid if you are planning to get pregnant and until you are 12 weeks pregnant
- iodine if you are pregnant or breastfeeding
- a probiotic if you are taking a long course or repeated courses of antibiotics
- vitamin B12 if you are vegan, particularly if you are breastfeeding, or older with a poor appetite
- vitamin D if you spend most of your time indoors, have dark skin, are pregnant or breastfeeding or cover most of your skin when outside
- iron, folic acid and vitamin D if you have newly diagnosed coeliac disease
- oral nutrition supplement drinks if you are underweight and struggling to put weight back on by eating normally
- omega-3 fish oils if you have high triglycerides (a type of fat) in your blood.
Low iron and iron deficiency anaemia
Pregnancy nutrients and supplements
Babies, children and vitamin D
Some pēpi are at higher risk of vitamin D deficiency. Vitamin D is essential for building strong bones and teeth. The recommendation in Aotearoa New Zealand is for all exclusively or partially breastfed pēpi to have vitamin D supplements until they are 1 year old.
Vitamin D and your baby — KidsHealth
Children and iron
Iron deficiency is common in tamariki and rangatahi. Iron is important for development, energy and growth.
Your healthcare provider can test for iron deficiency in tamariki and rangatahi and look for a possible cause. Usually it is managed with changes in diet or by taking iron supplements.
Risks of dietary supplements
Supplements, including herbal supplements, are not necessarily safer than prescription medicines just because they come from nature. In fact, several prescription medicines are chemicals that were found in nature and purified.
Many supplements are advertised as natural. But their ingredients are not always natural to the human body. Some may even have serious or unpleasant side effects.
Side effects
You are most likely to have side effects from supplements if you take them at high doses or if you take many different supplements.
Some supplements can increase the risk of bleeding.
If taken before surgery, some supplements can change your response to the anaesthetic. If you are having surgery, it is important to let your healthcare provider know what supplements you are taking. They can assess the risk of side effects.
Supplements can also interact with some medicines in ways that might cause problems. For example, vitamin K can reduce the ability of the blood thinner warfarin to prevent your blood from clotting.
Another supplement, St John's wort, interacts with some medicines. It makes some medicines less effective. With others, St John's wort can make the effects of the medicine stronger, which can lead to more side effects. Talk with your healthcare provider before starting St John’s wort.
Choosing a dietary supplement
- Make sure you really need the supplement. Talk to your healthcare provider, dietitian or pharmacist first.
- Always buy supplements from a reputable source such as your local pharmacy or supermarket, and not from an unknown company on the internet.
- Check the label. It should tell you how much to take, when to take it and how often, and how to store it. It should also have an expiry date.