Nutritional strategies for optimising bone health throughout the life cycle are extremely important, since a dietary approach is more popular amongst osteoporosis sufferers than drug intervention, and long-term drug treatment compliance is relatively poor. As an exogenous factor, nutrition is amenable to change and has relevant public health implications. With the growing increase in life expectancy, hip fractures are predicted to rise dramatically in the next decade, and hence there is an urgent need for the implementation of public health strategies to target prevention of poor skeletal health on a population-wide basis. The role that the skeleton plays in acid-base homeostasis has been gaining increasing prominence in the literature; with theoretical considerations of the role alkaline bone mineral may play in the defence against acidosis dating as far back as the late 19th century. Natural, pathological and experimental states of acid loading and/or acidosis have been associated with hypercalciuria and negative Ca balance and, more recently, the detrimental effects of ‘acid’ from the diet on bone mineral have been demonstrated. At the cellular level, a reduction in extracellular pH has been shown to have a direct enhancement on osteoclastic activity, with the result of increased resorption pit formation in bone. A number of observational, experimental, clinical and intervention studies over the last decade have suggested a positive link between fruit and vegetable consumption and the skeleton. Further research is required, particularly with regard to the influence of dietary manipulation using alkali-forming foods on fracture prevention. Should the findings prove conclusive, a “fruit and vegetable” approach to bone health maintenance may provide a very sensible (and natural) alternative therapy for osteoporosis treatment, which is likely to have numerous additional health-related benefits.

Aging is a complex biological process, which usually is accompanied by changes in socioeconomic status, which may have a great impact on the physical and nutritional status of the elderly. Decreased food intake and a sedentary lifestyle in the growing numbers of the elderly increase their risk for malnutrition, decline of bodily functions and developing chronic diseases. Oxidative stress is believed to be an important factor in aging and many age-associated degenerative diseases. Modulation of oxidative stress by energy restriction in animals has been shown to be one of the mechanisms for retarding the aging process. Dietary antioxidants are regarded as being important in modulating oxidative stress of aging and age-associated diseases. Supplementation of the elderly with vitamin E has been shown to enhance immune response, delay onset of Alzheimer's disease, and increase resistance to oxidative injury associated with exercise. Vitamin E, in comparison with other antioxidants, is also effective in reducing viral titres, but not the longevity of middle-aged mice. Our studies have indicated that polyphenols or vitamin E may assist in preventing cardiovascular disease, in part by decreasing expression by endothelial cells of proinflammatory cytokines, adhesion molecules, and monocyte adhesion. Most recently, we have found that some of these antioxidants may prevent tumour growth by inhibiting angiogenesis via suppression of interleukin 8 and modulation of the cell junction molecule, VE-cadherin. These findings provide further support for the consumption of fruit and vegetables, which contain several forms of phytochemicals with antioxidant activity, in order to reduce the risk of cardiovascular disease and cancer, the leading causes of morbidity and mortality among the elderly.

Osteoporosis is a common disease in the elderly, and the fractures that result from this disorder affect 40 % of women and 14 % of men over the age of 50 years. The risk of fracture relates to bone mineral density and the risk of falling, among other factors. Low bone mineral density in the elderly can result from either low peak bone mass or accelerated bone loss, or a combination of the two. Nutritional factors play a role in both the attainment of peak bone mass and in the rate of age-related bone loss. The main determinants of peak bone mass are genetic factors, early-life nutrition, diet and exercise. Of the nutritional factors Ca, and particularly milk, are the most important contributors to peak bone mass. Some of these factors may interact; for example, a low dietary Ca in addition to an unfavourable vitamin D receptor gene polymorphism may result in low peak bone mass. The age-related changes in bone mass may also have a genetic basis, but deficiency of oestrogen is a major contributor. In addition, undernutrition is common in the elderly, and lack of dietary protein contributes both to impaired bone mineral conservation and increased propensity to fall. There is a decreased ability of the intestine to adapt to a low-Ca diet with increasing age. Other dietary factors include vitamin K, Zn and fruit and vegetables. Adequate nutritional status, particularly of Ca and vitamin D, is essential for the successful pharmaceutical treatment of osteoporosis. Thus, strategies for enhancing skeletal health in the elderly must begin in early childhood, and continue throughout life.

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.

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.

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 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.

Nutritional epidemiology of cancer has gone through several stages. Initially, the long latency of cancer, the difficulties in undertaking long-term cohort investigations or ascertaining remote diet in case-control studies, and the absence of convenient intermediate biomarkers of disease, such as cholesterol in cardiovascular diseases, discouraged studies on diet and cancer. Subsequently, however, epidemiological successes in the chemical, viral and occupational aetiology of cancer, and the increasing insight into the sources of variation of diet and dietary information, prompted investigators to undertake both case-control and cohort studies. The results have been mixed. On the one hand, vegetables and fruits have been shown to be inversely associated with several forms of cancer. On the other hand, the information concerning specific macro- or micronutrients in relation to particular forms of cancer has been very limited and mostly inconclusive. There are several reasons for the complexity of investigations of the nutritional epidemiology of cancer and these reasons are briefly considered. An overview of our current understanding of the nutritional causes of cancer is also presented. It is noted that, notwithstanding the substantial gaps in our scientific knowledge, preventive nutritional approaches can be envisaged and they are likely to be moderately succeessful.

Supplementation has many potential advantages over fortification and dietary approaches for improving micronutrient intake. Pregnant and lactating women and infants are most likely to benefit from supplementation. Recent experience with vitamin A supplementation in young children has proved to be remarkably successful. Demonstrated efficacy of vitamin A supplements for improved child survival in many settings and a technical consensus on how to implement interventions were major factors in achieving this success. Bilateral and UN agencies worked together so that in 1999 80 % of children under 5 years of age in the least-developed countries received a vitamin A capsule in the last 6 months. At least one million child lives saved were associated with the increase in coverage in the last 2 years of the 1990s. Experience with Fe-folate supplements has not been as successful. Whilst a technical consensus has been reached on how to implement programmes to control Fe deficiency, the lack of convincing evidence of efficacy of Fe-folate supplements in terms of maternal and child survival outcomes has undoubtedly contributed to the limited pursuit of effective action. A new multiple micronutrient supplement for se amongst women of reproductive age in developing countries has been formulated. UNICEF is employing the supplement in programmes aimed at helping to prevent low birth weight. The new supplement is likely to be more efficacious than Fe-folate supplements for both maternal and child survival and development outcomes. Successful completion of rigorous efficacy trials will be critical for creating the political support needed to achieve universal coverage.

Food fortification is likely to have played an important role in the current nutritional health and well-being of populations in industrialized countries. Starting in the early part of the 20th century, fortification was used to target specific health conditions: goitre with iodized salt; rickets with vitamin D-fortified milk; beriberi, pellagra and anaemia with B-vitamins and Fe-enriched cereals; more recently, in the USA, risk of pregnancy affected by neural-tube defects with folic acid-fortified cereals. A relative lack of appropriate centrally-processed food vehicles, less-developed commercial markets and relatively low consumer awareness and demand, means it has taken about another 50 years for fortification to be seen as a viable option for the less-developed countries. The present paper reviews selected fortification initiatives in developing countries to identify different factors that contributed to their successful implementation, as well as the challenges that continually threaten the future of the se programmes. Ultimately, the long-term sustainability of fortification programmes is ensured when consumers are willing and able to bear the additional cost of fortified foods. There has been an enormous increase in fortification programmes over the last couple of decades in developing countries. Considerable progress has been made in reducing vitamin A and I deficiencies, although less so with Fe, even as Zn and folic acid deficiencies are emerging as important public health problems. Food fortification based on sound principles and supported by clear policies and regulations can play an increasingly large role in this progress towards prevention and control of micronutrient malnutrition.

The purpose of the present paper is to review the evidence in favour of food-based strategies to meet the challenges of micronutrient malnutrition in the developing world. Increasing dietary diversification is the most important factor in providing a wide range of micronutrients, and to achieve this objective in a development context requires an adequate supply, access and consumption of a variety of foods. Diets in developing countries generally lack many nutrients, including energy (inadequate amounts of food), so that strategies need to also emphasize an increase in total food intake, in addition to a greater variety. Agricultural and food policies tend to be oriented to primary agricultural productions, but they could also be formulated to promote and support home gardens and small livestock production for the explicit purpose of increasing the household consumption of micronutrient-rich foods. The adoption of ‘desirable’ dietary patterns for nutrition improvement, e.g. appropriately formulated to meet micronutrient needs, could be used in the formulation of agricultural policies and programmes. This process could be achieved through support for integrated farming systems oriented to assuring household food security, but also based on a variety of foods that will meet total dietary (including micronutrient) needs. Thus, availability of energy-rich staples, animal and/or fish as major sources of protein, and vitamin-, mineral- and phytonutrient-rich fruit and vegetables could constitute the types of production envisaged. The cultivation of edible indigenous plants as additional sources of micronutrients could also be added. The low bioavailability of some key micronutrients from foods, such as Fe, are substantially enhanced with the right food combinations and with appropriate food processing and preparation techniques. Simple appropriate technology for the preservation of micronutrientrich foods would need further development and promotion for their year-round availability. Linking community development policies to national programmes for the alleviation of hunger and malnutrition, with an emphasis on increasing the variety of foods consumed, is probably the best strategy for improving micronutrient malnutrition sustainably.

Micronutrient deficiencies occur frequently in refugee and displaced populations. These deficiency diseases include, in addition to the most common Fe and vitamin A deficiencies, scurvy (vitamin C deficiency), pellagra (niacin and/or tryptophan deficiency) and beriberi (thiamin deficiency), which are not seen frequently in non-emergency-affected populations. The main causes of the outbreaks have been inadequate food rations given to populations dependent on food aid. There is no universal solution to the problem of micronutrient deficiencies, and not all interventions to prevent the deficiency diseases are feasible in every emergency setting. The preferred way of preventing these micronutrient deficiencies would be by securing dietary diversification through the provision of vegetables, fruit and pulses, which may not be a feasible strategy, especially in the initial phase of a relief operation. The one basic emergency strategy has been to include a fortified blended cereal in the ration of all food-aid-dependent populations (United Nations High Commissioner for Refugees/World Food Programme, 1997). In situations where the emergency-affected population has access to markets, recommendations have been to increase the general ration to encourage the sale and/or barter of a portion of the ration in exchange for locally-available fruit and vegetables (World Health Organization, 1999a, b, 2000). Promotion of home gardens as well as promotion of local trading are recommended longer-term options aiming at the self-sufficiency of emergency-affected households. The provision of fortified blended foods in the general ration has successfully prevented and controlled micronutrient deficiencies in various emergency settings. However, the strategy of relying only on fortified blended foods to prevent micronutrient deficiencies should be reviewed in the light of recurring evidence that provision of adequate supplies of these foods is often problematic. Donor policies on the bartering or exchange of food aid should also be clarified. Furthermore, the establishment of micronutrient surveillance systems, including standardized micronutrient deficiency diagnostic criteria, are vital for the control of micronutrient deficiency diseases.

As a rule, children and most adults eat what they like and leave the rest. They like and consume foods high in fat and sugar. Parental behaviour shapes food acceptance, and early exposure to fruit and vegetables or to foods high in energy, sugar and fat is related to children's liking for, and consumption of, these foods. Some parents are imposing child-feeding practices that control what and how much children eat. However, over-control can be counter-productive, teaching children to dislike the very foods we want them to consume, and generally undermining self-regulation abilities. The external environment is also important, with concerns expressed about food advertising to children and girls dieting for an ideal thin body shape. Up to one-quarter of young adolescent girls report dieting to lose weight, their motivation driven by weight and shape dissatisfaction. For some, dieting and vegetarianism are intertwined and both legitimised as healthy eating. For others, striving for nutritional autonomy, the choice of less-healthy foods is not just because of their taste, but an act of parental defiance and peer solidarity. The determinants of what children choose to eat are complex, and the balance changes as children get older. A better understanding is crucial to informing how we might modify nutritional behaviour. Adults occupy a central position in this process, suggesting that children should be neither the only focus of nutritional interventions nor expected to solve the nutritional problems with which adults around them are continuing to fail.

Dietary changes can be difficult to effect both at an individual and at a population level, and even when changes do occur they are often far slower and less pronounced than might be expected. Three possible reason for this situation will be considered: the complexity of food choice and competing influences, attitudinal ambivalence and optimistic bias. Food choice is influenced by a large number of factors, not only health considerations, and therefore it is not surprising that interventions based primarily on health concerns have been ineffective. Another concern is that people do not always have clear-cut attitudes, but rather can be ambivalent about foods and about healthy eating, and this factor might impact on the translation of beliets and attitudes into behaviour. A third possible reason is optimistic bias, where individuals believe themselves to be at less risk from various hazards than is the average person. This effect has been demonstrated for nutritional risks, and this factor might lead people to take less note of health education messages. The stages-of-change model from health psychology has been proposed as a method for improving the effectiveness of behaviour change interventions. However, there are a number of problems in transferring such a model from smoking, where it was originally developed, to dietary behaviours, including the lack of clear-cut specific behaviours and behaviour change targets in the dietary field.

The present paper presents a non-technical overview of contemporary developments in food supply, as seen from the standpoint of economic adjustment. The historical concerns over availability and price of food have now passed in the UK, and agriculture is no longer dominantly driven by the supply-side forces of new farming technology and the stimulus of support policies. As a now demand-driven sector of the economy, it is the developing diversity of consumer food preferences that will increasingly determine the adjustment path of agricultural production. Those demands seek distinctive elements of food value, many of which are entirely created and delivered by industries beyond the farm gate. However, many of the quality characteristics of food that consumers increasingly seek are associated explicitly with what takes place on farms and how crop and livestock husbandry is conducted. In responding to these demand preferences many farmers will shift from being merely raw material producers to becoming genuine producers of food, or capturing more of the final value of the products consumed. As a result a dual structure within farming will develop, with a ‘quality agriculture’ becoming increasingly differentiated from a ‘commodity agriculture’ as two distinct strategies for farm business survival.

De novo lipogenesis is the biological process by which C2 precursors of acetyl-CoA are synthesized into fatty acids. In human subjects consuming diets higher in fat (>30 % energy), lipogenesis is down regulated and extremely low; typically < 10 % of the fatty acids secreted by the liver. This percentage will increase when dietary fat is reduced and replaced by carbohydrate, although the extent of carbohydrate-induced lipogenesis is dependent on the type of carbohydrate (monosaccharide v. polysaccharide) and the form in which the carbohydrate is fed (liquid meals, solid less-processed food). Clearly, massive overconsumption of carbohydrate can also increase lipogenesis. A second related phenomenon that occurs when dietary fat is reduced is hypertriacylglycerolaemia. This rise in blood triacylglycerol concentration could be due to increased de novo lipogenesis or to reduced clearance of lipid from the blood. The present paper will review the metabolic mechanisms leading to the elevations in blood triacylglycerol concentration that occur with dietary fat reduction. Studies considered will be those investigating fatty acid synthesis in subjects chronically fed low-fat high-carbohydrate diets and studies in which data were obtained in both the fasted and fed states. Also summarized will be data from subjects who had consumed diets of different carbohydrate types, as well as the most recent data from postprandial studies investigating factors that affect the magnitude of the rise in blood lipids following a meal. Given the changing availability of carbohydrate in the food supply, it will be important to understand how the balance of fat and carbohydrate in the diet influences lipogenesis, and the relative contribution of the process of de novo lipogenesis to the escalating incidence of obesity observed around the world.

There is a growing database that has evaluated the effects of varying amounts of total fat on risk factors for cardiovascular disease, diabetes and overweight and obesity. The evidence clearly suggests that extremes in dietary fat should be avoided, and instead a diet moderate in total fat (25–35 % energy) is preferable for the majority of individuals. Moreover, we now appreciate the importance of individualizing dietary fat recommendations within this range of total fat. With respect to cardiovascular disease, a diet higher in total fat (30–35 % energy) affects the lipid and lipoprotein risk profile more favourably than a lower-fat diet; this is also the case for individuals with diabetes, with the added benefit of better glycaemic control. Dietary fibre (≧25g/d) attenuates and even prevents the potentially adverse lipid and lipoprotein effects of a lower-fat diet. With respect to weight control, a moderate-fat diet can be as, or even more, effective than a lower-fat diet, because of advantages with long-term adherence and potentially favourable effects on lipids and lipoproteins. Thus, there is now a convincing scientific basis to advocate a diet moderate in total fat for the majority of individuals. Implicit to this position is that unsaturated fat has numerous beneficial health effects. However, because fat is energy dense, moderation in fat intake is essential for weight control. Consequently, a simple message to convey is to avoid diets that are very low and very high in fat. Moreover, within the range of a moderate-fat diet it is still important to individualize the total fat prescription. Nonetheless, the guiding principle is that moderation in total fat is the defining benchmark for a contemporary diet that reduces risk of chronic disease.

The role of high-fat diets in weight gain and obesity is assessed by evidence-based principles. Four meta-analyses of weight change occurring on ad libitum low-fat diets in intervention trials consistently demonstrate a highly significant weight loss of 3–4 kg in normal-weight and overweight subjects (P< 0·001). The analyses also find a dose-response relationship, i.e. the reduction in percentage energy as fat is positively associated with weight loss. Weight loss is also positively related to initial weight; a 10 % reduction in dietary fat is predicted to produce a 4–5 kg weight loss in an individual with a BMI of 30kg/m2. The non-fat macronutrient composition of the diet is also important. Whereas the glycaemic index of the carbohydrate may play a role for cardiovascular risk factors, there is so far no evidence that low-glycaemic index foods facilitate weight control. In contrast, intervention studies show that sugar in drinks is more likely to produce weight gain than solid sugar in foods. Although the evidence is weak, alcoholic beverages promote a positive energy balance, and wine may be more obesity-promoting than beer. Protein is more satiating and fhermogenic than carbohydrates, and one intervention study has shown that an ad libitum low-fat diet where carbohydrate was replaced by protein produced more weight loss after 6 months (8·1 v. 5·9 kg). The evidence linking particular fatty acids to body fatness is weak. If anything, monounsaturated fat may be more fattening than polyunsaturated and saturated fats, and no ad libitum dietary intervention study has shown that a normal-fat high-monounsaturated fatty acid diet is equivalent or superior to a low-fat diet in the prevention of weight gain and obesity. The evidence strongly supports the low-fat diet as the optimal choice for the prevention of weight gain and obesity, while the use of a normal-fat high-monounsaturated fatty acid diet is unsubstantiated.

As a result of the increasing consumer demand for minimally-processed fresh-like food products with high sensory and nutritional qualities, there is a growing interest in non-thermal processes for food processing and preservation. Key advanced technologies such as high-pressure processing, pulsed electric fields, dense gases and ultrasound are being applied to develop gentle but targeted processes to further improve the quality and safety of processed foods. These technologies also offer the potential for improving existing processes as well as for developing new process options. Furthermore, by adding new process dimensions (such as hydrostatic pressure, electric fields, ultrasonics, supercritical CO2) to the conventional process variables of temperature and time, they facilitate enlargement of the availability of unit operations. These operations might be applied effectively in unique combination processes, or as subsequent processing tools in more-targeted and subsequently less-intensive processes for food preservation and modification than the currently-applied processes.

Role of substrate utilization and thermogenesis on body-weight control with particular reference to alcohol By Yves Schutz Volume 59 (2000), Number 4 Figure 1, page 513