A meeting on the pharmacist's role in providing advice on nutrition was held at the public health nutrition unit, University of Leeds, on September 24
Compulsory units in nutrition featured in only four of 16 university pharmacy syllabuses and 80 per cent of 100 pharmacists questioned wanted more training in nutrition. These findings prompted staff from the public health nutrition unit at the University of Leeds to organise a one-day seminar for health professionals involved in advising patients and the general public on aspects of nutrition and supplementation.
Professor NICHOLAS READ (centre for human nutrition, University of Sheffield) said that there was a strong need for pharmacists to know more about nutrition and supplementation. Many supplements were sold from pharmacies and the pharmacist was promoted as the first port of call for advice.
Supplements used to be given solely for deficiency diseases but now they were being used to improve quality of life and were the largest over-the-counter (OTC) market in the UK. The philosophy of supplementation was that the modern diet did not provide enough micronutrients for the ever-increasing pace of life. Few people had time to eat sensibly and to exercise. Supplements were taken by those hoping to lessen the effects of ageing, mothers, those who were tired, stressed or rushed, those trying to lose weight, and those trying to bring their lives under control. Research had shown that supplement use was associated with a healthy lifestyle and adequate diet - ie, the "worried well" took supplements. Did this matter? Did supplements work? Could they cause harm? Were they food or medicine? Who decided?
The media often provided contradictory messages and Professor Read said that a voice of reason was needed. He suggested this could come from pharmacists. To do this, pharmacists needed to understand the current issues, know the role of nutrients in health and disease, and be able to answer the questions customers most frequently asked.
The current data on micronutrient requirements were based on physiological requirements to avoid deficiency states, stated Professor PETER AGGETT (Lancashire postgraduate school of medicine and health, University of Central Lancashire). However, reference values for promotion of better health and decreased risk of disease were needed. The driving force for this was industry and consumer pressure. To achieve definition of these reference values, a greater understanding of the physiological and pharmacological action of nutritional elements was required at the molecular and cellular level, and for the body as a whole. Most of the evidence for micronutrients was epidemiological. Prospective, hypothesis-led studies were now needed. A key component in this was the identification of markers and outcomes that were measurable, sensitive and specific. Any claim for a nutrient or food supplement should be sound, objective, appropriate, consistent and reproducible. In the future it might be possible to have targeted diets for specific age groups, lifestyles, genotypes and disease. The Functional Food Science in Europe project had been set up to promote research in understanding the role of food in human health.
Selective modification of the gut flora to alter health by the use of probiotics and prebiotics was not a completely crazy story, according to Dr JOHN CUMMINGS (Ninewells hospital and medical school, Dundee). The large intestine contained 1012 bacteria/g, and these formed an important component of digestion by the breakdown (fermentation) of non-starch polysaccharides and some oligosaccharides, which reached the colon intact. They also protected against pathogenic bacteria and stimulated the immune system. Live bacterial food ingredients (probiotics), such as bifidobacteria and lactobacilli, survived passage through the gut and temporarily altered the gut flora. They were most commonly found in yoghurts. Probiotics had been used successfully in some studies to treat or prevent diarrhoea and to improve symptoms in lactose intolerance.
Eating some oligosaccharides (prebiotics), such as inulin and fructo-oligosaccharides, could selectively stimulate the growth of probiotic-like bacteria normally present in the gut. Studies had used 7 to 15g/day doses that were mildly laxative and caused flatulence. Inulin and fructo-oligosaccharides occured naturally in artichokes and the onion family, and, to a lesser extent, in cereals. Many claims had been made for prebiotics, none of which had currently been proved. The Proprietary Association of Great Britain co-ordinated the Health Supplements Information Service, available at www.hsis.org, which aimed to provide information on micronutrients to the media and consumers.
Biological plausibility and epidemiology supported the role of antioxidant nutrients in health, said Professor ANTHONY DIPLOCK (international antioxidant research centre, United Medical and Dental School, University of London). Free radicals (having single unpaired electrons) were highly reactive and, in the process of gaining another electron, could cause damage to, for example, membrane lipoproteins. Damage to lipoproteins was a key factor in atherogenesis.
Nature had antioxidants to prevent free radical damage. These included superoxide dismutases (containing copper, zinc and manganese), glutathione peroxidase (containing selenium) and free radical scavengers, such as vitamin E and vitamin C.
Professor Diplock said that many epidemiological studies had shown that individuals with a high intake of vitamin E from foods or supplements had a lower incidence of cardiovascular disease. The amount of vitamin E required was about 100mg daily, which was much higher than that provided by a usual diet (15mg daily). There was also some evidence from prospective trials that vitamin E supplements might be beneficial and a few studies were ongoing.
Randomised controlled trials (RCTs) with clinical outcomes were the only evidence on which to base changes in the diet, according to Dr PETER JACKSON (department of clinical pharmacology and therapeutics, Royal Hallamshire hospital, Sheffield). Observational studies and biological plausibility should be used only to guide RCTs.
He said that fatty fish, fish oil supplements, n-3 polyunsaturated fatty acids and the Lyon (Mediterranean) diet had all been shown to have a protective role in the secondary prevention of cardiovascular disease in RCTs. The Diet and Reinfarction Trial (DART) study gave men fatty fish twice a week and the GISSI-P trial used n-3 polyunsaturated fatty acids at a dose of 1g daily. The Mediterranean diet was rich in alpha-linolenic acid, consisting of more bread, more root and green vegetables, more fish, less meat (only poultry), no day without fruit, and a rapeseed oil-based margarine. Also shown to be of benefit was a diet rich in fruit, nuts and vegetables. Dietary interventions of possible benefit in coronary heart disease were nuts, folic acid and wine. Folic acid decreased plasma homocysteine, which might be an independent risk factor for ischaemic heart disease. However, there were no clinical outcomes data for folic acid yet. Of the antioxidant vitamins, vitamin C had not shown any benefit, beta-carotene supplements were associated with an excess risk of lung cancer and no cardiovascular benefits, and the sum result of the vitamin E studies showed it had no benefits, although a few studies were ongoing.
Evidence suggested that vitamin D and calcium supplements had a role in the prevention of osteoporotic fractures in the elderly, said Dr FRAZER ANDERSON (department of geriatric medicine, Southampton General hospital). Once structural bone loss had occurred, it could not be replaced, even if bone mass density was increased and, therefore, prevention of osteoporosis was the key. Drugs to prevent osteoporosis were the sex hormones, bone hormones (vitamin D and calcitonin) and bone mineral therapy (calcium, bisphosphonates).
Vitamin D was required for regulation of calcium balance; a lack of vitamin D resulted in insufficient calcium absorption. To maintain plasma calcium in such cases, parathyroid hormone levels rose, which resulted in leaching of calcium from bone. Exposure of just the hands and face to half an hour of sunlight each day in a British summer allowed the body to produce sufficient vitamin D to last through the year. However, housebound elderly people might not get sufficient vitamin D, and their bone mass density gradually decreased, eventually resulting in osteoporosis. Dr Anderson explained that the Helsinki study showed that a single annual injection of vitamin D decreased the fracture rate in people older than 75 years, whereas the Amsterdam community study did not find a reduction in fractures in people older than 70 years taking daily oral vitamin D. Two studies had shown a reduction in fractures with the combination of vitamin D and calcium taken daily in the elderly. There were currently three studies ongoing in the UK, including one of annual vitamin D injections in the elderly, and one of oral supplements of vitamin D alone, calcium alone, and the combination.
Discussing the use of fish oils in rheumatoid arthritis, Dr PHILIP CALDER (institute of human nutrition, University of Southampton) explained that humans required polyunsaturated fatty acids in the diet. Linoleic acid (omega-6 series) was metabolised to arachidonic acid from which pro-inflammatory mediators were derived. Alpha-linolenic acid (omega-3 series) was metabolised to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), from which mediators with "anti-inflammatory" effects were derived. Fish oils contained EPA and DHA. In numerous pharmacological studies, fish oils decreased inflammatory effects, including monocyte, neutrophil and eosinophil chemotaxis, production of tumour necrosis factor and interleukins, and adhesion molecule expression. Fish oils at a dose of six to 12 capsules per day had shown some clinical benefit in patients with rheumatoid arthritis in a number of small trials of three to 12 months' duration. Benefits included reduction in joint stiffness and reduced use of non-steroidal anti-inflammatory drugs (NSAIDs). Fish oils might, therefore, be a dietary equivalent to aspirin.
An alternative to fish oils would be alpha-linolenic acid, found in rapeseed oil, walnuts and sweet potatoes. Dr Calder added that pro-inflammatory mediators were involved in fighting infection. More data, therefore, were needed on the overall effects and optimum dietary levels of these substances.
Food should be fortified with folic acid to reduce the incidence of birth defects such as spina bifida, according to Dr CHRISTOPHER SCHORAH (division of clinical sciences, University of Leeds). There was good evidence that folic acid at a dose of 500mg daily would prevent neural tube defects in pregnancy. It was not possible to achieve this level from the diet. A diet of dark green vegetables, pulses and liver would provide a maximum of about 400mg of folic acid. Folic acid supplements of 400mg a day had, therefore, been promoted for use before conception and during the first 12 weeks of pregnancy. However, the neural tube was formed very soon after conception (from the 14th to 22nd day), a stage when women often did not know that they were pregnant. Since 40 per cent of pregnancies were unplanned, by the time these women realised they were pregnant it was too late. The level of awareness of the need to take folic acid before pregnancy among women of childbearing age was also low.
Food fortification was, therefore, the most effective way of ensuring that women had an adequate intake of folic acid before they conceived. This might eventually be shown to have the additional benefit of reducing the risk of ischaemic heart disease since folic acid decreased plasma homocysteine. This appeared to be an independent risk factor for ischaemic heart disease. Doses of folic acid of about 5,000 to 10,000mg daily had been shown to mask pernicious anaemia (vitamin B12 deficiency) and to prevent effective anticonvulsant therapy, but the levels anticipated from food fortification would not be expected to have this effect. The UK Government was currently looking at the issue. - from Dr C. Rhoda Lee.