Almost anything that is swallowed in pill or potion form that is not a licensed medicine is, by default, legally classified as a dietary supplement. The present paper is an overview of supplement use and is intended to provide a logical framework for their discussion. Five major supplement categories are identified: essential micronutrients; other metabolites that have vitamin-like roles; natural oils; natural plant or animal extracts; antioxidants, which span the other categories. Supplement usage is also classified into broad categories. Examples of each supplement category and usage are briefly discussed. Some potential hazards of supplement use are also outlined; many substances in supplements are either not found in normal UK diets or consumed in much greater amounts than would be found in food. Many supplements are used for pharmaceutical purposes and sold as supplements to avoid the expense of acquiring a medicinal licence and to avoid the stricter quality-control regulations that apply to medicines. The use of supplements to ensure nutritional adequacy and as possible conditionally-essential nutrients is briefly discussed, as is their essentially pharmaceutical use for the prevention and alleviation of disease. There is critical discussion of whether the use of antioxidant supplements is justified or even if it is reasonable to promote a particular food on the basis of antioxidant content alone. Much of the research on supplements is reductionist, commercially sponsored or has other weaknesses; so, despite decades of use and research there is still uncertainty about their efficacy in many cases.

Within the last decade there has been a dramatic increase in the sale and use of herbal supplements and food supplements by Western populations and within the UK. This increased usage has coincided with a resurgence of interest in nutritional therapy and complementary and alternative medicine (CAM) therapies, such as herbal medicine, naturopathy and homeopathy, in which therapists may provide dietary advice and advocate the use of food or herbal supplements. The rise in the use of CAM therapies by the UK population can be attributed to several factors, including: promotion via health programmes and the media; a change in public attitudes; training of more nutritional and CAM therapists as a result of the increased availability of courses; a greater use of CAM and food and herbal supplements, particularly by patients with cancer. The aim of the present paper is to identify the pattern of usage of food and herbal supplements in the UK.

The use of complementary medicines in patients suffering from chronic illnesses such as cancer and depression is widely documented. Current studies suggest that the prevalence of the use of complementary medicines in patients with cancer ranges from 7% to 80%. In patients suffering from severe depression the use of complementary medicines may be >40%. The aim of the present review is to systematically explore the main dimensions that clinicians have to consider when advising patients suffering from these conditions. The Medline and Cochrane databases were searched for evidence relating to the benefits and risks of supplements in the treatment of cancer and depression, including the potential interactions with pharmaco- and radiotherapy. Supplements predominantly used by patients with cancer include vitamins A, C and E, β-carotene and ubiquinone 10. Supplements predominantly used by patients with depression include S-adenosylmethionine, l-tryptophan and 5-hydroxytryptophan and inositol. Supplements potentially used by both groups include n-3 fatty acids, Se and folic acid. Four dimensions are identified and discussed: effectiveness; safety; communication; medico-legal aspects. These dimensions have to be addressed in an illness- and case-specific context. This task can be complex given the emerging clinical evidence, patients' own preferences and expectations and current prescribing guidelines.

The use of vitamins, minerals and other supplements has increased considerably during recent years. In the National Diet and Nutrition Survey of British adults aged 19–64 years 40% of those surveyed were taking supplements. In 2005 sales of dietary supplements in the UK were approximately £325·7×106 in ‘bricks and mortar’ shops (excluding health food shops). The physiological effects of vitamins and minerals in amounts approximating to the UK reference nutrient intake or the EU RDA are well understood in terms of reducing the risk of micronutrient deficiency. However, the effects of vitamins, minerals and other supplements in larger amounts have attracted much attention in recent decades, and these effects, some of which may be pharmacological, are not as well categorised. Some of these effects are beneficial, some are not. Although vitamins and minerals and other supplements are generally safe at higher doses, there are some safety issues that are relevant in the context of the wide availability of supplements without a doctor's prescription. Thus, several authorities throughout the world have established upper limits (UL) for the intake of vitamins and minerals, and the EU is in the process of setting maximum permitted levels (MPL) for vitamins and minerals in food supplements. The present paper discusses the potential benefits and safety issues relating to the use of supplements at doses higher than the RDA. The rationale for the establishment of UL is also discussed, explaining the differences between the values set by different authorities and the expected guidance and legislation from the European Commission on MPL for vitamins and minerals in food supplements.

In 2000 an estimated £335×106 was spent on food supplements and herbal remedies in the UK. Until recently, The Trades Description Act 1968, the Food Safety Act 1990 and The Food Labelling Regulations 1996 (amended 2004) were the only form of regulation available to protect the public. The medical community has been concerned about the risk to patients of inaccurate dosages and poor-quality products as well as drug–nutrient and nutrient–nutrient interactions. Following growing concern about the type and quality of food supplements and herbal remedies available in the EU, the European Commission has published directives regulating food supplements (2002/46/EC) and herbal remedies (2004/24/EC and 2004/27/EC) available within the EU. The directives came into force in 2005 and limit the number and quality of permitted food supplements through the creation of a ‘positive list’ of approved supplements. In the present paper the new regulatory frameworks and the implications for the food supplement manufacturers, traditional and complementary therapists, the healthcare professions and patients will be examined. It would appear that there is considerable dissatisfaction with the regulations in their present form. Several questions remain: is regulation the answer; who decides which nutrients go on the positive list; what effect has the regulation had on patient safety and patient choice?

2006 marked the centenary of the birth of Dr Elsie Widdowson, a pioneer of nutrition science. One of the hallmarks of Elsie Widdowson's research was an integrative approach that recognised the importance of investigating the mechanisms underpinning a public health or clinical issue at all levels, looking into the physiology, comparative biology, intermediate metabolism and basic science. The theme of the present lecture, given in celebration of the work of Dr Widdowson, is mineral nutrition, with a particular focus on Ca, P and vitamin D. The contributions of Dr Widdowson to the early understanding of mineral nutrition are reviewed and the latest scientific findings in this rapidly-expanding field of research are presented.

Malnutrition (undernutrition) is one of the many health inequalities facing governments in the 21st century. Malnutrition is a common condition affecting millions of individuals in the UK, particularly older adults, the sick and those cared for within the healthcare system. It costs the National Health Service >£7·3×109 annually. New data highlight marked geographical differences in the prevalence of malnutrition across England and an inter-relationship between deprivation, malnutrition and poor outcome. As malnutrition is a largely treatable condition, prompt identification and effective prevention and treatment of this costly condition is imperative. Routine screening for malnutrition in high-risk groups (e.g. the elderly and those in areas with high deprivation) and within the healthcare system should be a priority, with screening linked to appropriate plans for the management of malnutrition. Use should be made of specialised interventions, including oral nutritional supplements and artificial nutrition, to aid recovery and improve outcome, with skilled health professionals, including dietitians, involved where possible. Equity of access to nutritional services and treatments for malnutrition needs to occur across the UK and, although complex and multi-factorial, the effects of deprivation and other relevant socio-economic and geographical factors should be addressed. Ultimately, as malnutrition is a public health problem, its identification and treatment must become a priority for governments, healthcare planners and professionals.

Parenteral nutrition is life saving in patients with intestinal failure but liver dysfunction is commonly encountered, especially in neonates. Although abnormal liver function tests associated with short-term parenteral nutrition are usually benign and transient, liver dysfunction in both children and adults receiving long-term parenteral nutrition can progress to end-stage liver disease and liver failure. The aetiology of parenteral nutrition-associated liver disease is complex and multifactorial, with a range of patient, disease and nutrition-related factors implicated. Sepsis is of particular importance, as is the lack of enteral nutrition and overfeeding with intravenous glucose and/or lipid. Deficiencies of a number of amino acids including choline and taurine have also been implicated. Management of hepatic dysfunction in parenteral nutrition should initially focus on preventing its occurrence. Sepsis should be managed appropriately, enteral nutrition should be encouraged and maximised where possible and parenteral overfeeding should be avoided. Provision of parenteral lipid should be optimised to prevent the adverse effects of both deficiency and excess, and cyclical rather than continuous parenteral feeding should be administered. There is some evidence of benefit in neonates from oral antibiotics to prevent intestinal bacterial overgrowth and from oral ursodeoxycholic acid, but less to support their use in adults. Similarly, data to support widespread use of parenteral choline or taurine supplementation are lacking at present. Ultimately, severe parenteral nutrition-associated liver disease may necessitate referral for small intestine and/or liver transplantation.

Despite a great deal of research effort there is still considerable uncertainty surrounding the importance of the B-vitamins in health and disease. This continuing uncertainty is partly a result of the difficulty of measuring intake, confounding in observational studies and the very large numbers required to evaluate primary prevention in randomised controlled trials. Consequently, genetic data are increasingly being used to infer nutritional effects on health and even in the formulation of nutrition policy using the approach of ‘mendelian randomisation’. Genetic information has already contributed greatly to the understanding of B-vitamin metabolism and the heterogeneity of responses to intake. It has the potential to provide further nutritional insights and to assist in the elucidation of causal mechanisms, but it is important that genetic data is not viewed as an alternative to nutritional information, both are necessary when addressing nutritional problems. Similarly, the interpretation of nutrient and biomarker status in some experimental designs may require knowledge of genotype. Formal tests of gene–gene and gene–nutrient interaction are of limited value in nutritional studies and the formulation of policy. Graphical representation of diet–genotype–health data greatly assists in the elucidation of the nature of genetic effects, their interaction with nutrition and the implications for nutrition policy.

In the UK vitamin B12 deficiency occurs in approximately 20% of adults aged >65 years. This incidence is significantly higher than that among the general population. The reported incidence invariably depends on the criteria of deficiency used, and in fact estimates rise to 24% and 46% among free-living and institutionalised elderly respectively when methylmalonic acid is used as a marker of vitamin B12 status. The incidence of, and the criteria for diagnosis of, deficiency have drawn much attention recently in the wake of the implementation of folic acid fortification of flour in the USA. This fortification strategy has proved to be extremely successful in increasing folic acid intakes pre-conceptually and thereby reducing the incidence of neural-tube defects among babies born in the USA since 1998. However, in successfully delivering additional folic acid to pregnant women fortification also increases the consumption of folic acid of everyone who consumes products containing flour, including the elderly. It is argued that consuming additional folic acid (as ‘synthetic’ pteroylglutamic acid) from fortified foods increases the risk of ‘masking’ megaloblastic anaemia caused by vitamin B12 deficiency. Thus, a number of issues arise for discussion. Are clinicians forced to rely on megaloblastic anaemia as the only sign of possible vitamin B12 deficiency? Is serum vitamin B12 alone adequate to confirm vitamin B12 deficiency or should other diagnostic markers be used routinely in clinical practice? Is the level of intake of folic acid among the elderly (post-fortification) likely to be so high as to cure or ‘mask’ the anaemia associated with vitamin B12 deficiency?