Winter would seem the perfect time to reach for a multi-vitamin, to keep you at your fighting fittest – but what exactly constitutes a multi-vitamin, and do they really deliver?
What is a multi-vitamin?
Strictly speaking, a multi-vitamin is a supplement that contains a combination of vitamins. But in practise, the term is used to refer to products that contain both vitamins and minerals, and in some cases, other added ingredients such as herbs like ginseng or gingko biloba.
The primary purpose of a multi-vitamin is to fill a nutritional gap in instances where diet is nutritionally inadequate or where there are specific increased nutrient needs. For example, post-menopausal women have increased calcium requirements.
Are they safe?
Some studies on multi-vitamins have reported findings that are a cause for concern, for example:
The 2008 VITAL (VITamins And Lifestyle) study found that an increase in vitamin E supplementation was associated with an increased risk of lung cancer, particularly among smokers.
More recently, a 10-year prospective study of more than 35,000 women found that women who took a daily multi-vitamin were nearly 20 per cent more likely to develop breast cancer.
However, the majority of studies support the safety of multi-vitamins. A 2009 Women’s Health Initiative study on supplement use did not find any significant links between multi-vitamin use and the likelihood of developing cancer or cardiovascular disease.
What’s safe for me?
If you do choose to add a multivitamin to your daily routine, it is important to keep in mind that the safe intake level is not necessarily the same for all population groups and life stages. For example, pre-menopausal women require 18mg iron a day while men need only 8mg. Similarly, a multi-vitamin that contains vitamin A may be appropriate for most of the population, but can cause birth defects if over-consumed by pregnant women. The best thing to do is to consult with your GP or a dietitian about what multi-vitamin is best for your needs.
Do they work?
Again, published opinion is conflicting. A 2002 literature review of the role of vitamin supplementation in the prevention of chronic disease by researchers at Harvard University surmised that ‘it appears prudent for all adults to take vitamin supplements.’ But in contrast, an expert panel convened by the US National Institutes of Health concluded that most of the studies examined did not provide strong evidence for beneficial health-related effects of supplements taken singly, in pairs, or in combinations of three or more.
What health professionals do agree on, however, is that while taking a multi-vitamin might not offer any measurable benefits, it is unlikely to cause any harm, provided the doses are age and life-stage appropriate.
How do I choose the best multi-vitamin?
In Australia, there are recommended intakes for 14 vitamins and 14 minerals and trace elements. Multi-vitamins generally meet or exceed 100 per cent of certain vitamin requirements, but include a far smaller proportion of minerals. But don’t assume that a multivitamin contains all of the vitamins and minerals you need, or that they provide 100 per cent of the recommended amounts. There is no regulation requiring manufacturers to do so.
Nutrient intakes are typically expressed as Recommended Dietary Intakes (RDIs), which represents an intake that will meet 97 per cent of the healthy population’s needs. The most recent Nutrient Reference Values have also included an additional Suggested Dietary Target (SDT) for certain nutrients that may help in the prevention of some chronic diseases. The SDT is generally higher (but sometimes lower, as is the case with sodium) than the RDI. See www.nhmrc.gov.au/ publications/synopses/n35syn.htm for more information.
Are multi-vitamins as effective as food?
Nutrients are absorbed more efficiently from food than from supplements, so it’s best to meet your nutrient needs with a healthy diet. Taking supplements has also been shown to negatively affect the body’s absorption of some nutrients. However, some interactions can be positive – such as taking vitamin C with iron, which greatly increases iron absorption.
Some vitamins are also better absorbed than others. Water-soluble vitamins, such as vitamin C, dissolve easily in water and are excreted from the body once the body has reached its daily threshold. Because they aren’t stored in the body, daily intake of water-soluble vitamins is important. On the other hand, fat-soluble vitamins, such as vitamin A, are not excreted as easily from the body, so they can reach harmful levels in the body if over-consumed.
What about minerals?
With the exception of iron, minerals are less likely to be over-consumed in a multivitamin. This is because our mineral requirements are far greater (as much as 50 times!), so the tablet/capsule would be too big. It’s a good idea to talk to your doctor about what mineral supplements – if any – you should take.
Unfortunately, most vitamin manufacturers do not list the percentage of RDIs contributed on their product label, which can make it difficult to judge if you are choosing the most appropriate product. If you have questions, call the manufacturer – they should be able to tell you how much of the RDI is being provided, or consult your doctor.
Many of us could probably benefit from adding a multi-vitamin to our daily routine; but it’s best not to view them as the main source of your daily vitamins and minerals. unless you have specific requirements (ie. – pregnancy, post-menopausal status etc), the best way to look at a multi-vitamin is as ‘insurance’, against the possibility that you are not meeting your nutrient needs through a healthy and varied diet.
For the general healthy population, a multi-vitamin that provides roughly the RDI for the vitamins and contributes some of the RDI of key minerals such as calcium should be all that is needed. Many multi-vitamins contain some iron, which is appropriate for most people, but some multi-vitamins contain no iron.
The addition of herbs to multi-vitamins is becoming increasingly popular, although they are not essential in a multi-vitamin preparation. If you choose a multi-vitamin with herbs, be sure to discuss it with your GP first to ensure that it is appropriate for you.
Centrum Complete contains 27 essential vitamins and minerals, with the vitamins at or near 100 per cent of the RDI. This product is one of the only multi-vitamin products to list the RDIs next to the dosage so you know how much you are getting.
Blackmore’s Sustained Release Multi-Vitamin is suitable for both men and women and releases the vitamins and minerals over a prolonged period of time.
Nature’s Way Advanced Multi delivers an immediate release of selected vitamins into the stomach, and a 12-hour sustained release of other vitamins as the tablet travels through the small intestine.
Centrum Select 50+ is formulated for men and women over the age of 50. Compared to regular Centrum, it contains increased levels of selected vitamins and minerals, such as some B group vitamins, folic acid and antioxidants, such as vitamins E and C.
Berocca Performance with 12 vitamins and minerals, this is a great on-the-go option if you want a pleasant tasting way to boost your nutrient intake.
Nature’s Way Kids Choc Orange chewable multi-vitamins contain 17 essential vitamins and minerals and can be chewed or squeezed into food or drink. Not suitable for children under 2 years of age without medical advice.