In the literal sense, a multivitamin is a dietary supplement that contains several vitamins. In reality, it is more often one that contains a combination of vitamins, minerals and phytonutrients beneficial for human health.
Multivitamin supplements generally provide between half and double the recommended daily amount (RDA) of a given nutrient. They come in various forms (tablets, capsules, pastilles, powders …) and are taken once or several times a day depending on the composition.
As we know, vitamins and minerals play a key role in many essential physiological functions. For example:
A multivitamin supplement is therefore a welcome source of additional nutrients providing daily support for your health. In no circumstances, however, should it be seen as a substitute for a balanced diet and healthy lifestyle: just because you’re dutifully taking a course of multivitamins doesn’t mean you can eat fast food every day!
What’s more, specific population groups may benefit in particular from supplementing with vitamins and minerals as they are more likely to develop deficiencies: vegans who exclude animal-source products from their diet, the elderly who tend to have smaller appetites, those under intense stress, top athletes… (4-7)
Does the science support multivitamin supplementation? Led by Harvard University in 2012, the large-scale Physicians' Health Study II looked at the effects of taking multivitamin supplements among a sample of 14,641 subjects over several years. Significant results were observed at a cellular level (8).
A, B, C, D, E, K, Mo, Zn… in understanding this new ‘multivitamin alphabet’, the first thing to say is that a good supplement should offer doses close to recommended daily amounts … without ever exceeding upper safe levels. In the case of strong>iodine for example, 150 µg/day is deemed to be a sufficient intake according to the EFSA (European Food Safety Authority), but you should not exceed 600 µg/day.
It’s worth noting that with certain water-soluble vitamins such as vitamin C, there is a greater degree of flexibility. As any excess vitamin is eliminated via urine, the risk of overdosing is minimal.
How about minerals? According to a study conducted between 2001 and 2002, the magnesium intake of 48% of the US population was below the RDA. Yet this mineral plays a crucial role in supporting normal muscle and nervous system function (9). So a multivitamin is all the better for including it in its formulation (though not above a level of 250mg/day in the form of dissociable magnesium or magnesium oxide).
With regard to trace elements, zinc, selenium, iodine and molybdenum all play a role in numerous enzyme and/or hormone reactions. It therefore makes sense to boost your daily intake of them through supplementation.
Conversely, there are some substances that should be viewed with caution, including iron and copper. In individuals who already have adequate amounts, supplementing with these minerals could raise levels to the point where they exert an adverse prooxidant effect on cells (10-11).
Beware too of controversial synthetic excipients! Magnesium stearate and silicon dioxide contain nanoparticles, thought to pose a risk to health.
While it’s important to scrutinise the list of substances in a multivitamin supplement, it’s also vital that these substances are bioavailable! To offer genuine health benefits, multivitamins need to contain the forms of vitamins and minerals absorbed most effectively by the body. For example, according to the latest studies, pyridoxal-5-phosphate is the most bioactive form of vitamin B6 (12).
For optimal absorption, it is also appropriate to prioritise natural sources which are more suited to human physiology - like d-alpha tocopherol for vitamin E or selenomethionine for selenium.
Is it just vitamins and minerals in these supplements? Drawing on the most up to date scientific data, certain formulations have chosen to include phytonutrients and other active compounds to produce comprehensive synergistic effects.
Amongst others, you’ll find certain carotenoids (such as lutein and lycopene), quercetin, apigenin, and the famous pyrroloquinoline quinone (PQQ) – which is currently the subject of several promising studies into its effects on mitochondria (13). There’s no doubt that a whole new era is opening up in the world of multivitamins!
If you’re planning to start taking a multivitamin, the supplement Daily 3 combines no less than 42 ingredients selected for their high bioavailability– including 12 vitamins, 8 minerals, and carefully-selected phytonutrients (lutein, anthocyanins, luteolin, apigenin …) with a recommended dose of 2 to 3 vegetarian capsules a day.
If you’re particularly busy or preoccupied, it may be better to opt for a supplement that only needs to be taken once a day (such as Daily 1, which combines 30 active substances in a one-a-day tablet).