Supplements: because they’re worth it?

It’s a minefield out there – with so many brands, doses and combinations, how can consumers know which vitamins or minerals they should take – if they should take any at all? Walk into any health food shop or pharmacy chain, and you’ll be faced with shelves stocked full of vitamins, minerals and herbal supplements claiming to maintain health or alleviate a diverse array of symptoms. Confronted with a sea of single, paired and multivitamins, with or without added herbal this-and-that, consumers have a tough choice deciding which product is right for them. But is it worth the hassle? Is there any benefit to popping a daily supplement, or is the consumer’s health – and that of their wallet – put at risk by manufacturers’ claims? Vitamin and mineral supplements are worth big bucks – the market in the UK was worth over £674.6 million in 2009, of which multivitamins and fish oils were the most popular, contributing £138.6m and £139.1m respectively¹. Advocates say there is nothing to suggest that taking a daily nutritional supplement is dangerous. Dr Howard Sesso, an associate professor of epidemiology at the Harvard School of Public Health agrees: “There are potential benefits and there are no known risks at this time. It’s worth considering a multivitamin as part of a healthy lifestyle. Multivitamin supplementation is low risk and low cost, and it helps fill potential gaps in the diet that people might have.”² People choose to take supplements believing their diet is lacking in some way but in the developed world, eating a healthy, balanced diet should provide all the vitamins and minerals a person needs. When you consider the recommended daily intake of Vitamin C is 80mg, and an orange contains 70mg, it doesn’t seem that hard to do. Could supplements therefore be causing an excess of certain vitamins and minerals in the body? What happens to them once there and are they dangerous? Vitamins are either water soluble or fat soluble. The eight B vitamins and vitamin C are water soluble and used rapidly by the body – any excess is excreted rather than stored, meaning that expensive vitamin C tablet to ward off the flu is literally just money being flushed down the toilet. However, the story is not that simple, says Dr Alan Stewart, a doctor specialising in nutrition. “The water soluble vitamins are not completely harmless,” he says. “In very high quantities, some vitamins can accumulate. Vitamin B could be linked with problems with the metabolism, and data from the US has linked excess vitamin C with breast cancer, although we have not seen this trend in the UK data.” The fat soluble vitamins – A, D, E and K – are stored in the liver and fat tissues. Any excess is able to accumulate in the body, which could lead to hypervitaminosis. “Excessive amounts of vitamin A can have side effects such as abdominal pain, weight loss, vomiting, blurred vision, irritability and headache,” Dr Emma Williams, a nutritional scientist with the British Nutrition Foundation says¹.

It’s difficult reach a dangerous level of a mineral or vitamin from diet alone

Stewart says hypervitaminosis A is most common, particularly in the older population where 5-10% of over 65s suffer the condition. He says this is associated with an increase in osteoporosis – as too much vitamin A can make your bones brittle and more likely to fracture – particularly in older women where around 20% take a supplement. High levels of minerals can also cause problems in the body. Although minerals are absorbed in smaller quantities than vitamins, they can be harder to excrete and cause problems. Too much beta-carotene can increase the risk of lung cancer developing in smokers and those heavily exposed to asbestos at work, while excess boron and cobalt can decrease fertility in men. Too much copper can cause stomach pain, sickness and diarrhoea, and damage to liver and kidneys if taken for a long time, while surplus manganese causes muscle pain, nerve damage and neurological symptoms³. It’s difficult reach a dangerous level of a mineral or vitamin from diet alone, says Stewart, adding that hypervitaminosis and an excess of minerals in the body is becoming more prevalent thanks to nutritional supplements. “You have to work at it, but it is possible, and that’s thanks to the internet. The internet has given us access to stupid supplements in megadose quantities,” he says. “Most of these supplements are produced in the US, he says, but there are a few UK based companies too. Consumers take these megadose supplements over a period of months and quite often don’t realise the effects these pills are having on their bodies.” Other than replacing something that is lacking, people take supplements to help keep them healthy: many claim to help maintain or boost the immune system, sustain bone health and cut the risk of chronic disease like cancer. However, there is little evidence to support the claims made by supplement manufacturers. The European Food Safety Authority looked at the science behind assertions made on thousands of different supplements to see if they stood up under scrutiny. According to consumer watchdog Which? of the thousands of claims checked, 80% could not be upheld¹. Academic findings are in agreement. A study reviewing almost 30 trials of multi-, single or paired vitamins concluded that there was no clear evidence of the beneficial effects of supplements on mortality, cardiovascular disease or cancer⁴. A second strand looked at cognitive performance and verbal memory, while a third studied data on recurrent cardiovascular events. Both revealed no significant differences between the supplement-taking and placebo groups. “The message is simple,” say the study’s authors, “Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided. This message is especially true for the general population with no clear evidence of micronutrient deficiencies.” And this message is reaffirmed by other studies. Vitamin B supplements don’t slow mental decline and therefore aren’t likely to prevent Alzheimer’s disease⁵ found a University of Oxford team who compared the effect of B vitamins on cognitive decline in older people against a placebo. Although the vitamins reduced the level of homocysteine in the blood – high levels of which have been linked to Alzheimer’s – this had no effect on mental abilities. “Our study draws a line under the debate: B vitamins don’t reduce cognitive decline as we age,” says Dr Robert Clarke, who led the work. “Taking folic acid and vitamin B-12 is sadly not going to prevent Alzheimer’s disease.” “Taking supplements like B vitamins doesn’t prevent heart disease, stroke or cognitive decline,” he adds. “About 25–30% of the adult population take multivitamins, often with the idea that they are also good for the heart or the brain, but the evidence just isn't there. Much better is to eat more fruit and vegetables, avoid too much red meat and too many calories, and have a balanced diet.” Similarly, a systematic review on glucosamine and chondroitin supplements – which purportedly help protect the joints – showed they had little beneficial effect on osteoarthritis. The supplements supposedly supply the materials needed to rebuild the cartilage worn away in those with the disease, but neither alleviated joint pain or curtailed the condition in any way⁶. In fact, the National Institute for Health and Clinical Excellence (NICE) do not recommend its use: “The use of glucosamine or chondroitin products is not recommended for the treatment of osteoarthritis.” Fish oil supplements are one of the more popular products and are reported to have a wide range of beneficial effects. A key component of fish oils is omega-3 fatty acids, important for the maintenance of good health and a major structural component of cell membranes, especially present in the brain. While one study found that regular use of fish oil supplements was associated with a significant reduction in cognitive decline and brain atrophy in older adults – but only for participants without dementia at the time of enrolment⁷ – many academic reviews have found a lack of beneficial effect of omega-3 fatty acids on cancer, dementia and asthma and no evidence that it reduces the risk of cognitive impairment and cardiovascular events^8-10. How are companies able to make these assertions if the evidence suggests dietary supplements have no benefit? Manufacturers must abide by the advertising guidelines set out by the Advertising Standards Authority, which can take action against false or misleading claims made against UK-based companies at least. Rules state that advertisements must not suggest that it is necessary or therapeutic for the average person to augment their diet or that dietary supplements can enhance normal good physical or mental condition¹¹. Any claims for health benefits should be considered in the context of a balanced diet and healthy lifestyle and it is here that manufacturers are shrewd in the claims they make, pointing out that although their product is a food supplement, it should not be used as a substitute for either. Manufacturers are wary not to claim the product treats or cures a condition – only maintains a function. This means supplements are not classed as medicinal and are not subject to the rigorous MHRA regulations which medicines and drugs are. Instead supplements are classified as foodstuffs and are covered by the Food Safety Act, Food Supplementation Regulations and general food laws from the Department of Health, in the UK at least. Supplements should also only be made with vitamins and minerals appearing on an EU approved ingredient list. But even then, they may also contain other “acceptable” ingredients – including bulking agents used to build up the vitamin tablets to a suitable pill size – which can also have biological effects on the body. If taken with other licensed medicine or other supplements, they can become unsafe. Herbal supplements, for example, are a particular danger. Researchers in Canada carried out DNA barcoding on 44 bottles of popular supplements sold by 12 companies and found that many were not what they claimed to be^12,13. Worryingly, two bottles of St John’s wort – a suggested remedy for depression – contained none of the herb; one was simply powdered rice, while the other contained Alexandrian senna, an Egyptian yellow herb that is a powerful laxative. Echinacea tablets are popular with those wanting to boost their immune system and fend off colds, but pills contained ground up Parthenium hysterophorus, an invasive plant linked to rashes, nausea and flatulence while gingko biloba supplements, promoted as memory enhancers, contained black walnuts, a deadly hazard for those with a nut allergy. The research also showed many supplements were adulterated with rice, soybean and wheat – another potential allergen. While a small proportion of the population will be advised to take a vitamin or mineral supplement at some point in their life, evidence suggests that there is little benefit to popping a multivitamin pill every day. The biggest effect multivitamins have is on the consumers’ wallet, and are likely to be nothing more than a waste of money. Should anyone take supplements? In some instances, specific vitamins are recommended for certain sections of the population.

• Women hoping to conceive and those in early pregnancy are advised to take folic acid – also known has vitamin B9 – to prevent neural tube defects such as spina bifida in the growing foetus.
• Pregnant and breastfeeding women, those over 65 and those with darker skin or limited sun exposure are advised to take a Vitamin D supplement, which will help to regulate calcium in the body and maintain healthy bones.

Anyone falling outside these categories is unlikely to need a vitamin or mineral supplement unless recommended by a doctor. References

1. Supplements, Who needs them? A Behind the Headlines report (June 2011) http://www.nhs.uk/news/2011/05May/Documents/BtH_supplements.pdf
2. Do multivitamins make you healthier? http://www.health.harvard.edu/newsletters/harvard_mens_health_watch/2014/april/do-multivitamins-make-you-healthier?
3. http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Other-vitamins-minerals.aspx
4. Enough is enough: stop wasting money on vitamin and mineral supplements (December 2013) http://annals.org/article.aspx?articleid=1789253
5. Taking B vitamins won’t prevent Alzheimer’s disease (July 2014) http://www.ox.ac.uk/news/2014-07-16-taking-b-vitamins-won%E2%80%99t-prevent-alzheimer%E2%80%99s-disease
6. Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis (July 2010) http://www.bmj.com/content/341/bmj.c4675.full
7. Davey Smith G, Riemersma R, Ebrahim SAssociation of fish oil supplement use with preservation of brain volume and cognitive function (June 2013 (http://www.alzheimersanddementia.com/article/S1552-5260(14)00079-X/abstract
8. Omega 3 fatty acid for the prevention of dementia. Cochrane Database of Systematic Reviews 2006, Issue 1. Lim W-S, Gammack JK, Van Niekerk JK, Dangour A
9. Omega 3 fatty acids for prevention and treatment of cardiovascular disease. Cochrane Database of Systematic Reviews 2004, Issue 4. Hooper L, Harrison RA, Summerbell CD, Moore H, Worthington HV, Ness A, Capps N,
10. Docosahexaenoic acid supplementation increases prefrontal cortex activation during sustained attention in healthy boys: a placebo-controlled, dose-ranging, functional magnetic resonance imaging study (January 2010) http://ajcn.nutrition.org/content/91/4/1060.abstract
11. Compliance Report Health and Beauty Products and Therapies Advertisements Survey 2009 http://www.asa.org.uk/News-resources/~/media/Files/ASA/Reports/Health_Beauty_survey_2009_Final.ashx
12. Herbal supplements are often not what they seem, New York Times (November 2013) http://www.nytimes.com/2013/11/05/science/herbal-supplements-are-often-not-what-they-seem.html
13. DNA barcoding detects contamination and substitution in North American herbal products (October 2013) http://www.biomedcentral.com/1741-7015/11/222/abstract

Author Kerry Taylor-Smith is Web Editor on Laboratory News and has a degree in Natural Sciences from the University of Bath.