My curiosity regarding the accuracy of health claims of supplements and functional foods was initiated during a visit to a health food chain store in London a few years ago. Perusing the store, I was amazed at how many physiological processes such supplements were claimed to support.
‘Omega 3 fatty-acids – may help maintain cognition, bone health and a healthy heart’.
‘Ginseng – aids memory, concentration, cognition, behaviour, and maintains quality of life’.
I continued meandering. As a then-Biological Sciences student, I became increasingly suspect of the notion that any solitary supplement could have such a far-reaching impact upon the processes of the human body.
In the depths of winter, I also had a common cold, and was told by the same shop assistant, in response to my intermittent coughing and spluttering, “I would recommend Echinacea for you, Sir”. “Echi-what?”, I replied. I was given another explanation of yet another miraculous supplement – this one supposedly having the potential to reduce my cold symptoms and speed up my recovery. I was not convinced. Thus began a personal mission to research the topic of dietary supplements and substantiate –or refute – such claims.
Who takes dietary supplements and why?
There are a few groups that are advised to take supplements – pregnant and breastfeeding women, those aged four months to five years, elderly people, and those with little to no sun exposure, and some individuals with co-morbidities (although these are assessed on a case by case basis). The vast majority of people, however, do not need to be taking supplements. Yet many people do not realise they do not require them, and are lured into purchasing them by attractive packaging and debatable health claims.
Despite the grim economic climate that much of the UK is experiencing, overall sales of vitamins and dietary supplements show no sign of abating. According to the National Diet and Nutrition Survey, 33% of adults aged 19-64 years, 22% of young people, and 40% of adults 65 years and older reported consuming dietary supplements within the last year. According to Food Standards Agency Research, the main reason people report taking supplements is for general health and wellbeing.
Arguably the biggest fad is high-strength water-soluble vitamins. Once consumed, the body uses what it can, with the rest flowing out of your body unabsorbed. In the midst of an obesity epidemic, weight loss supplements are also popular as a ‘quick fix’; however, no clinically relevant effects were observed in the most popular products. And what about the Echinacea I was nearly wooed into forking out on? It turns out I would have been wasting my money – again, no evidence of effectiveness.
More worryingly, the safety of some dietary supplements is questionable. Ancient alchemist Paracelsus noted: “All substances are poisons. There is none which is not a poison – the right dose differentiates a poison and a remedy”. Indeed, many herbal supplements contain biologically active ingredients that can cause adverse effects in the body, becoming toxic at high doses and interfering with other pharmacological drugs. Further, high doses of some vitamins and minerals have been linked to an increased risk of heart disease and cancer.
Most dietary supplements are classified as foods and fall within the legislative domain of the Food Supplements (England) Regulations (2003), the Food Safety Act (1990) and the Food Labelling Regulations (1996). This means that, unlike medicinal products, many dietary supplements are not subject to testing of safety, quality or efficacy.
It is reassuring to read that since my visit to the supplement store a few years ago, the European Food Safety Authority has passed new laws whereby nutrition and health claims need to be assessed and authorised. Thus far, around 80% of claims from manufacturers have been rejected, based on insufficient evidence.
The rise of nutraceuticals and functional foods
Aside from dietary supplements, ‘nutraceuticals’ – food and drinks that claim to provide a health benefit – also suffer from misleading claims and a lack of regulation. Energy drinks are a class of nutraceutical, the consumption of which is becoming increasingly prevalent in today’s society. Although no estimates of prevalence are available in the UK, in the USA, consumption in those aged 12-17 years was reported as 31%. In a qualitative study currently being carried out by DECIPHer researchers exploring teachers’ perceptions of health in schools, a recurring issue is the prevalence of energy drink consumption in young people and the effects of this on students’ ability to learn. Research exploring how and why young people are consuming such drinks, and gauging the parental views of energy drinks, would be valuable. Alternatively, schools could take a more top-down approach, following the lead from a Derbyshire school, which banned energy drinks last week.
How this impacts upon public health research
From a public health perspective, it is essential that the mantra of a healthy diet, combined with regular physical activity, is reinforced. Although NHS Choices produced a detailed guide on dietary supplements, this document has not been widely publicised. According to the All Party Parliamentary Group for Children, Personal, Social, Health and Economic (PSHE) education should be mandatory and available for all children. It is vital to educate children and adolescents (as well as parents) about the benefits and potential harms of dietary supplements and functional foods such as energy drinks, which use clever marketing ploys to lure unsuspecting consumers to purchase products under false pretences. PSHE education or health promotion campaigns could be an effective means of achieving this.