Multivitamin myths

The multivitamin world is confusing and unregulated. Will taking a supplement really give you shinier hair or preventyou from getting sick? Bupa Dietitian Rosalyn D’Angeolo looks past the marketing to give us the facts.

Think of it this way: multivitamins can be an insurance policy. They can potentially help you fill gaps in your nutrition, during times when you’re very busy, stressed or run down. Can you eat junk and take a multi-vitamin to give your body everything it needs? Nope. We know that vitamins do not replace a healthy diet. But sometimes they can be useful.
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When they’re useful

Vitamins can be very useful for people who do not eat certain foods. For example, people who follow a vegan lifestyle may need to take vitamin B12, calcium and iron as these are the nutrients commonly lower in diets that contain no animal products. These should be taken under the supervision of a dietitian or doctor. For those people who get stomach upsets when drinking milk, calcium fortified almond milk or calcium fortified soy milk can help make up the difference in calcium that they would otherwise miss out on.

We know that certain deficiencies can cause side effects in the body. For example, too little potassium, calcium or magnesium in your diet can contribute to leg cramps. In this instance, a supplement may assist with symptoms. Iron deficiency can cause people to feel extremely lethargic, so an iron supplement in this instance is extremely beneficial.

Another time when vitamins become very important is when a woman is trying to conceive. It's recommended that during this time, women take a pregnancy supplement to ensure that the growing foetus gets enough folic acid, iron and iodine. These nutrients are essential for the normal growth and development of the foetus. 

When they’re dangerous

Taking one particular vitamin in higher doses (e.g. iron) when you’re not deficient can actually lead to a build-up of that vitamin in your system, which can cause toxicity. So if you’re feeling tired, get your iron levels checked before taking an iron supplement. If it is low, you would typically be recommended to take iron for 3 months and then have it re-tested to see if it’s back to normal. If it is, you stop taking the supplement. Supplementing with a particular vitamin or mineral over a long period of time without checking the levels in your system is not recommended.

The other thing to know is that taking more of something when you’re not deficient in it has no benefit. For example, if you’re getting enough vitamin C in your diet from fresh fruit and veg, then you take vitamin C to prevent getting sick, it probably won’t make much of a difference. 

There are water soluble vitamins and fat soluble vitamins. The fat soluble vitamins A, D, E and K can all be stored in the body - so these are particularly dangerous when taken in high doses without a doctor’s supervision.
In comparison, the water soluble vitamins are just excreted through your urine when they’re not needed by the body, which is why you might notice your urine is fluro green when you take a multivitamin. That’s the vitamins that your body already has enough of going straight in to the toilet.

Some vitamins and minerals can also interact with medication. If you’re taking prescribed medication, check with your doctor or pharmacist before starting any supplements.

Take home messages

  • A general multivitamin can act as an insurance policy during times where you might not be looking after yourself as well as you normally do
  • If you think you might be deficient in something, go to your doctor and get a blood test. Only then should you supplement your diet with a certain type of vitamin, if prescribed.
  • If you can’t or don’t eat a particular food group, see a dietitian to work out which vitamins you might be at risk of having too little of. A supplement may be recommended at that stage.
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