Osteoporosis is almost universal in very old age, and is a major cause of morbidity and mortality in the elderly of both sexes. Bone is lost at a rate of 0·2–0·5 %/year in both men and women after the age of 40–45 years. The causes of age-related changes in bone mass are multifactorial and include genetic predisposition, nutritional factors, endocrine changes, habitual exercise levels and body weight. Bone loss is accelerated to 2–5 % year immediately before and for up to 10 years post-menopause (Heaney, 1986). In women hormone-replacement therapy is effective in reducing the rate of bone loss caused by this peri-menopausal decrease in hormone levels (Smith & Studd, 1993); however, in men and older women (>10 years post-menopause) nutrition plays a key role in the rate of bone loss. One factor contributing to bone loss in the elderly may be a subclinical Zn and/or Cu deficiency, due to a reduced dietary intake of micronutrients and reduced absorption (Thomson & Keelan, 1986). Zn and Cu are essential cofactors for enzymes involved in the synthesis of various bone matrix constituents. Paradoxically, Ca supplementation may accentuate the problem of reduced Zn and Cu levels by impairing the absorption of simultaneously-ingested Zn and the retention of Cu (Snedeker et al. 1982; Grekas et al. 1988). The present paper will review the current literature on the potential benefits of Cu and Zn supplementation in reducing bone loss, and present new information on the effect of Ca supplementation on Zn and Cu status in post-menopausal women with osteoporosis.

Emphasis on public health and consumer protection, in combination with globalisation of the food market, has created a strong demand for exposure assessments of food chemicals. The food chemicals for which exposure assessments are required include food additives, pesticide residues, environmental contaminants, mycotoxins, novel food ingredients, packaging-material migrants, flavouring substances and nutrients. A wide range of methodologies exists for estimating exposure to food chemicals, and the method chosen for a particular exposure assessment is influenced by the nature of the chemical, the purpose of the assessment and the resources available. Sources of food consumption data currently used in exposure assessments range from food balance sheets to detailed food consumption surveys of individuals and duplicate-diet studies. The fitness-for-purpose of the data must be evaluated in the context of data quality and relevance to the assessment objective. Methods to combine the food consumption data with chemical concentration data may be deterministic or probabilistic. Deterministic methods estimate intakes of food chemicals that may occur in a population, but probabilistic methods provide the advantage of estimating the probability with which different levels of intake will occur. Probabilistic analysis permits the exposure assessor to model the variability (true heterogeneity) and uncertainty (lack of knowledge) that may exist in the exposure variables, including food consumption data, and thus to examine the full distribution of possible resulting exposures. Challenges for probabilistic modelling include the selection of appropriate modes of inputting food consumption data into the models.

Consumer concern regarding possible adverse health effects of foods produced using intensive farming methods has led to considerable interest in the health benefits of organically-produced crops and animal products. There appears to be widespread perception amongst consumers that such methods result in foods of higher nutritional quality. The present review concludes that evidence that can support or refute such perception is not available in the scientific literature. A limited number of studies have compared the nutrient compositions of organically- and conventionally-produced crops, with a very small number of studies that have compared animal products (meat, milk and dairy products) produced under the two agricultural systems. Very few compositional differences have been reported, although there are reasonably consistent findings for higher nitrate and lower vitamin C contents of conventionally-produced vegetables, particularly leafy vegetables. Data concerning possible impacts on animal and human health of diets comprising organic or conventional produce are extremely sparse. Data from controlled studies in animal models, particularly within single species, are limited or poorly designed, and findings from these studies provide conflicting conclusions. There are no reports in the literature of controlled intervention studies in human subjects. Comparison of health outcomes in populations that habitually consume organically- or conventionally-produced foods are flawed by the large number of confounding factors that might contribute to any differences reported. If consumer perceptions regarding potential health benefits of organic foods are to be supported, more research of better quality is needed than that which is currently available.

Re´sume´Les allergies alimentaires repre´sentent un sujet important pour la sante´. La pre´valence chez les adultes d'Europe Occidentale est estime´e entre 1 et 2 %, tandis que parmi les enfants elle est plus e´leve´e (autour de 5 %). La plupart des allergies confirme´es sont associe´es à une gamme de produits relativement re´duite, dont le lait de vache, les ufs, les noix, les cacahue´tes, le ble´, les poissons et les fruits de mer. Cependant, il est connu que la pre´valence des allergies aux aliments spe´cifiques varie selon la zone ge´ographique, en raison principalement des diffe´rences dans les habitudes alimentaires. Bien que nous n'en ayons pas la preuve formelle, on suppose que le nombre de cas d'allergie alimentaire, comme celui des autres formes de maladies atopiques, est en augmentation. Il n'y a aucun doute que la pre´disposition ge´ne´tique est un de´terminant important. Toutefois, il est connu que l'acquisition de la sensibilisation aux prote´ines alimentaires et par la suite au proble`me d'allergie est influence´e par un e´ventail de facteurs environnementaux, ainsi que par le moment, la dure´e et l'intensite´ de l'exposition. De plus, la nature de l'allerge`ne lui-meme peut avoir un rle tre`s important sur la se´ve´rite´ et la persistance de la maladie clinique. Notre objectif est ici de discuter de l'importance de quelques-unes de ces variables dans le contexte des re´ponses allergiques immunoglobuline E-dependant.

Development of an orally-administered systemic agent that could reduce the effects of u.v. exposure on skin could potentially have a major effect on the incidence of skin cancers and photo-ageing. A number of micronutrients have been suggested to have metabolic properties that could induce this protection, and our data indicate that n–3 polyunsaturated fatty acids are particularly effective in this role. The mechanisms of action of n–3 polyunsaturated fatty acids appear to depend on their anti-inflammatory properties, acting to reduce the u.v.-induced release of cytokines and other mediators from a variety of skin cell types.

Home parenteral nutrition is required by patients with intestinal disease such that they are unable to maintain nutritional status or fluid volume without this treatment. A Managed Clinical Network has been established in Scotland. The aims of this multi-professional group are to ensure equity of access and that patients are managed according to nationally-agreed evidence-based procedures and protocols. The Clinical Standards Board for Scotland has provided support in preparing a quality-assurance framework to which the network must adhere.

In contrast to the situation in the USA, where a wide range of genetically modified (GM) foods is available, in Europe very few GM products have been approved for marketing as foods, and there is widespread public concern about their safety and environmental impact. The marketing of a GM crop for food use in Europe falls under the EC novel foods regulations, and applications require the submission of an extensive dossier of information. The safety evaluation of GM foods presents considerable problems both in the conduct and interpretation of experimental studies, because conventional toxicity tests used in the evaluation of simple chemicals may not be appropriate for whole foods. To rationalise the safety evaluation process and to circumvent the difficulties in toxicological assessment of food materials, the concept of substantial equivalence has been developed. The concept is that if it can be demonstrated that the novel food is essentially similar to its conventional counterpart in terms of critical nutritional or anutritional components, then it is likely to be no more or less toxic than the latter. The possible introduction of unintended effects by the genetic modification process is particularly problematic for the safety evaluation process. The new genomic and post-genomic techniques are potentially valuable in the safety evaluation of GM foods, although they are as yet in their infancy.

Résumé

La génomique de la volaille a bénéficié des avancements technologiques rapides acquis en génomique humaine et sur les organismes modèles. Certains outils et certains approches sont maintenant bien établis chez le poulet, y compris les cartes et marqueurs (génétiques comme physiques), mapping loci pour caractéres quantitatifs, mapping comparative, ressources expressed sequence tag et bacterial artificial chromosome, et mapping physique. De plus, la phase suivante de la découverte génétique, la génomique fonctionnelle, est en cours. Les progre`s dans le mapping de loci pour caracte`res quantitatifs de croissance et d'adiposité seront discutés pour illustrer ces nouvelles technologies et ces nouvelles approches dans l'étude de la génétique et de la physiologie avicole.

Peroxisome proliferator-activated receptor (PPAR) α represents an important member of the nuclear hormone receptor superfamily that can be activated by a variety of natural fatty acids, some of their metabolites and by commonly-used anti-lipidaemic drugs. We recently demonstrated PPARα expression in T lymphocytes, where it controls the initiation of transcription of T-box expressed in T-cells (T-bet) independent of added agonist. T-bet is an activation-inducible transcription factor regulator of interleukin 2 (suppression) and interferon γ (stimulation) synthesis. A suppressed ability to produce interleukin 2 and an enhanced production of interferon γ occurs in activated T-cells from PPARα-/- mice, as well as in T-cells from wild-type aged animals whose lymphocytes express lowered basal levels of PPARα. The dysregulated expression and/or function of cytokines, glucocorticoids or leptin that occurs with advanced age could all be responsible for the reduced expression of PPARα. Dietary supplementation of aged mice with vitamin E, or supplementation with known agonists of PPARα, was associated with elevation of lymphocyte expression of this nuclear hormone receptor, restoration of control over T-bet expression and elimination of the dysregulated production of interleukin 2 and interferon γ following lymphocyte activation. Interleukin 2 and interferon γ play very important roles in the initiation and/or regulation of immune, inflammatory and autoimmune disease states. Thus, the mechanisms that control the timing, magnitude and duration of specific cytokine production by activated T lymphocytes need clarification before appropriate nutritional or therapeutic strategies can be devised to treat disease conditions where cytokine expression and/or activities are deemed to be dysregulated and responsible.

Oxidative damage is present within the brains of patients with Alzheimer's disease (AD), and is observed within every class of biomolecule, including nucleic acids, proteins, lipids and carbohydrates. Oxidative injury may develop secondary to excessive oxidative stress resulting from β-amyloid-induced free radicals, mitochondrial abnormalities, inadequate energy supply, inflammation or altered antioxidant defences. Treatment with antioxidants is a promising approach for slowing disease progression to the extent that oxidative damage may be responsible for the cognitive and functional decline observed in AD. Although not a uniformly consistent observation, a number of epidemiological studies have found a link between antioxidant intake and a reduced incidence of dementia, AD and cognitive decline in elderly populations. In AD clinical trials molecules with antioxidant properties such as vitamin E and Ginkgo biloba extract have shown modest benefit. A clinical trial with vitamin E is currently ongoing to determine if it can delay progression to AD in individuals with mild cognitive impairment. Combinations of antioxidants might be of even greater potential benefit for AD, especially if the agents worked in different cellular compartments or had complementary activity (e.g. vitamins E, C and ubiquinone). Naturally-occurring compounds with antioxidant capacity are available and widely marketed (e.g. vitamin C, ubiquinone, lipoic acid, β-carotene, creatine, melatonin, curcumin) and synthetic compounds are under development by industry. Nevertheless, the clinical value of these agents for AD prevention and treatment is ambiguous, and will remain so until properly designed human trials have been performed.

The rapid globalization of the world economy has increased the need for a knowledge base of reliable socio-cultural differences in perceptions, values and ways of thinking about new food technologies. Awareness of socio-cultural differences is important because collaborative efforts to deal with food hazards presuppose some understanding of where, how and why the viewpoints of various stakeholders may differ. In the present paper factors that influence public perceptions of genetically-modified (GM) food are discussed, with a special focus on the unique circumstances of populations in the USA, Europe and developing countries. It is argued that effective communication and decision making about the risk of GM food depends critically on understanding how socio-cultural groups differ in their values and in the way they deal with the risks and benefits of new technologies. The implications of psychological aspects of perceived risk (including the roles of qualitative dimensions of risk, world views and trust) for public acceptance of new food technologies are highlighted.

Re´sume´Parmi les ge`nes dont les produits jouent un rle critique dans la re´gulation de la re´ponse immune, on trouve les familles de ge`nes de l'antige`ne leucocyte humain (ALH) et de la cytokine. Les ge`nes ALH sont les plus polymorphes du ge´nome humain, et ce polymorphisme entraine des diffe´rences fonctionnelles des mole´cules ALH exprime´es, qui se traduit par des diffe´rences individuelles dans la manie`re dont des peptides antige´niques se pre´sentent aux cellules T. De plus, un nombre conside´rable de polymorphismes des ge`nes associe´s a la cytokine ont e´te´ identifie´s, la plupart d'entre eux se produisent au niveau du promoteur de ces ge`nes, ce que dans de nombreux cas se traduit par l'expression diffe´rentielle in vitro de leurs respectifs produits ge´ne´tiques pro- ou anti-inflammatoire. Des polymorphismes ALH particuliers aboutirent a` des associations bien de´finies avec un grand nombre de maladies immunologiquement medie´es, parmi lesquelles quelques-unes avec des facteurs de risque die´te´tique. Par exemple, des individus de ge´notype HLA-DQA1*0501, DQB1*0201 ont un risque deux cent fois plus grand de de´velopper une intole´rance au gluten alimentaire (maladie ce´liaque), et des facteurs additionnels en relation avec l'ALH peuvent influencer le de´veloppement d'un lymphome maligne dans une maladie ce´liaque existante. De mme, des alle`les HLA-DRB1 qui partage une se´quence motive commune constituent le premier facteur de risque ge´ne´tique de l'arthrite rhumatode. L'influence de polymorphismes associe´s a une expression de cytokine diffe´rentiel sur la susceptibilite´ aux maladies pre´sent dans ce moment un grand inte´rt. La plupart de l'attention a e´tait centre´ les associations avec la susceptibilite´ de maladies medie´es immunologiquement be´nignes, parmi eux un grand nombre de maladies de l'intestin. Toutefois, un travail re´cent dans notre laboratoire indique que les polymorphismes de la cytokine peuvent influencer la susceptibilite´ a` certains cancers (ainsi que son pronostic), entre eux le me´lanome de peau maligne et des tumeurs solides qui peuvent tre affecte´s par l'alimentation, comme le cancer de prostate (collaboration avec le CRC/BPG e´tude familial du cancer de prostate Royaume-Uni). De plus, des travails pre´liminaires sugge`rent que la modulation par l'alimentation des niveaux d'expression de certaines cytokines dans des sujets humains peut tre de´pendent du ge´notype.

The essential trace mineral, Se, is of fundamental importance to human health. As a constituent of selenoproteins it plays both structural and enzymic roles, in the latter context being best known as an antioxidant and catalyst for the production of active thyroid hormone. While Se-deficiency diseases have been recognised for some time, evidence is mounting that less-overt deficiency can also cause adverse health effects and furthermore, that supra-nutritional levels of Se may give additional protection from disease. In the context of these effects, low or diminishing Se status in some parts of the world, notably in some European countries such as the UK, is giving cause for concern. While deficiency has an adverse effect on immunocompetence, Se supplementation appears to enhance the immune response. Se appears to be a key nutrient in counteracting certain viral infections; thus, in a Se-deficient host the benign coxsackie virus becomes virulent, causing heart damage, the influenza virus causes more serious lung pathology and HIV infection progresses more rapidly to AIDS. Long recognised as essential for successful animal reproduction, Se is required for human sperm maturation and sperm motility and may reduce the risk of miscarriage. Deficiency has been linked to adverse mood states. Findings have been equivocal in linking Se to cardiovascular disease risk, although other conditions involving oxidative stress and inflammation have shown some association with Se status. There is growing evidence that higher Se intakes are associated with reduced cancer risk. While persuasive evidence already exists to suggest that additional Se would be beneficial in some health conditions, results from intervention trials underway or planned have the potential to reinforce or refute the argument for increasing Se intake.

Dietary fatty acids have numerous effects on cellular function, many of which are achieved by altering the expression of genes. The present paper reviews recent data on the mechanisms by which fatty acids influence DNA transcription, and focus specifically on the importance of three transcription factors: peroxisome proliferator-activated receptor α; liver X receptor α; sterol regulatory element-binding protein 1c. These data indicate that fatty acids induce or inhibit the mRNA expression of a variety of different genes by acting both as agonists and as antagonists for nuclear hormone receptors.