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Our 101 guide to vitamins and supplements

"In an ideal world we would get all the nutrients we need from a healthy diet, we would exercise regularly and get at least eight hours sleep a night; we wouldn't smoke, drink or get stressed out. Back in the real world, however, things are very different," says Healthspan's Dr Sarah Brewer.

"But, with as many different dietary supplements available as there are conflicting messages about them, it can be hard to know what is best for you. There are also questions of how best to take them, when to take them, how much is too much and other important considerations," she says.

With this in mind and with the help of Dr Sarah, we have put together a comprehensive guide on how to make the most out of your vitamins and minerals. 

Blue alarm clock

First things first: find a routine

So that your body can make the most out of the supplements you take, it's important to take them regularly and at the right time of day. It's so important, in fact, that we've dedicated an article to supplement routines.

See When's the best time to take my supplements? for more information.

What's the difference between vitamins and supplements?

If we look at the definition of supplement, it means "something that completes or enhances something else when added to it."

Now we already know the former part of Vitamin, 'vita' means life. But did you know that the latter part, 'min', is derived from the longer word 'Amine' which is the name of a class of compounds to which vitamins were originally thought to belong?

In effect a health supplement, such as a vitamin D supplement, is a method of aiding, enhancing or simply supporting your health.

Contained within a supplement is the actual vitamin, which in the case of vitamin D can only be obtained naturally by your body through sunlight.

There are vitamins called A, B, C, D, E, and K...
...But what happened to vitamins F, G, H, I, and J?

Now that's a good question.

Hint… a lot of them got re-identified as part of the vitamin B complex.

Vitamin F

Reissued as an Essential Fatty Acid (EFA) a long time ago – think omega-3 and omega-6.

Vitamin G

Previously this was the American name for what the Brits called B2. Now both sides of the Pond know it as 'riboflavin'.

Vitamins H and I

You'll probably know vitamin I from its colloquial form 'ibuprofen'. Vitamin H, more commonly known as biotin, is part of the B complex group of vitamins.

Vitamin J

Vitamin J was once identified as choline, which was also formerly considered to be a B vitamin (vitamin B4).

Choline is one of the missing B numbers, along with inositol (vitamin B8) and para amino benzoic acid (PABA), which is sometimes referred to as vitamin B10.

Supplement Safety

What are RNIs?

RNIs (Reference Nutrient Intakes) are the levels of intake of essential nutrients that are considered to meet the known needs of most healthy people.

Upper safe levels

Nutritional scientists have identified upper tolerable levels for the long-term use of vitamin and mineral supplements. These reflect the doses that most people can take every day without experiencing side effects.

In many cases, these doses are a lot higher than the NRV in your supplement. For a few supplements, however, the upper safe level is close to the recommended daily amount (e.g. for iron and magnesium).

Red telephone

Top supplement safety tips

● If you order from Healthspan's call centre, their Nutritional Advisors will automatically let you know if you are likely to go above upper safe limits based on the supplements you purchase.

● If you have a medical condition and are thinking about taking supplements always check with your doctor or pharmacist first. This is especially important if you are taking prescribed medicines or over-the-counter remedies. Many drugs are known to interact with foods or supplements, so always check for potential interactions before you take them.

● Check your supplement expiry dates! To make sure you don't buy too many supplements, consider subscribing to your favourite Healthspan products. That way packs will arrive when you need them, and you'll never run out. Out-of-date supplements can go in your household food bin.

Combining supplements

If you are combining supplements that might contain the same vitamins or minerals, check the combined doses carefully to ensure you do not breach upper safe levels except under medical advice (e.g. to treat iron-deficiency anaemia).

What about supplements that already combine vitamins and minerals?

Some supplements have a synergistic effect when used together, which is why glucosamine and chondroitin is one of the most popular combined supplements. Calcium and vitamin D are also often used together as vitamin D enhances the absorption of calcium from the intestines. Similarly, vitamin C boosts the uptake of dietary iron. One of the most popular combinations for many people is a multivitamin and mineral plus an omega-3 fish oil as this provides a good foundation for nutritional health.

Water soluble versus fat soluble

Vitamins fall into one of two categories based on their solubility. Water soluble vitamins dissolve in water and are readily lost from the body via the kidneys. A regular, daily intake is therefore important to avoid deficiencies. In contrast, fat soluble vitamins are more readily stored in liver and fat cells, so it takes longer for low dietary intakes to lead to a deficiency. It is important not to exceed recommended doses of fat soluble vitamins as excess could build up in the body to cause toxicity.

Examples of water soluble vitamins

  • Vitamins B1, B2, B3, B5, B6, B12, folate, biotin, C.
  • Vitamin B12 is unusual as, although it is water soluble, the liver can store significant amounts.

Examples of fat soluble vitamins

  • Vitamins A, D, E and K

For more information on optimal supplement use, see Get the most out of your supplements.

Dr Sarah Brewer is Healthspan's Medical Director and holds degrees in Natural Sciences, Surgery and Medicine from the University of Cambridge. Having worked as a GP and hospital doctor, Dr Sarah now holds an MSc in Nutritional Medicine from the University of Surrey and specialises in nutrition. She is also an award-winning writer and author.

Find out more at Dr. Sarah Brewer's website, or read more about Healthspan's health experts.

Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn't possible, supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.