1. The deposition of fat during pregnancy and its subsequent mobilization during lactation was studied in the rat. The utilization of protein during lactation was also investigated.2. Fat accumulation was rapid and continuous from early pregnancy. Approximately one-third was deposited subcutaneously, the remainder being stored in central depots.3. The volume of milk produced during lactation was varied by offering protein at two concentrations from day 2 post partum. Optimum lactation was achieved with a high-protein diet. The dams lost no body protein, but 60% of the total body fat was mobilized, despite a marked increase in food consumption. On a low-protein diet, food intake did not rise during lactation. Some body protein was catabolized and, again, 60% of the fat was mobilized although milk output, as judged by the gain in carcass energy of their pups, was reduced to approximately one-third of optimum. 4.Protein was used more efficiently by lactating rats, when compared with virgin controls. 5. We conclude that fat stored during pregnancy makes a major contribution to the energy costs of lactation, and that its mobilization is under hormonal rather than dietary control.

A high sodium intake, to which bread makes a major contribution, and a low potassium intake are believed to be important factors in the promotion of cardiovascular disease. Our aims was to determine to what extent salts of potassium could substitute sodium chloride and potassium-rich soya flour could replace wheat flour without detrimental effect on acceptability, and to measure the bioavailability of a potassium salt added to bread. A single-blind organoleptic evaluation was carried out on eight different potassium-enriched breads by 41 panellists. Thereafter, six volunteers consumed standard or potassium-chloride-fortified bread in an 11-day single-blind cross-over feeding trial to determine the bioavailability of the supplemental potassium. Two breads in which 30% of the sodium was replaced by potassium salts, and bread in which 10% of wheat flour was replaced with soy flour, had acceptability scores similar to the standard bread. In the metabolic study a supplement of 22 mmol/day potassium chloride incorporated into the bread was found to be wholly bioavailable. A substantial reduction in sodium and an increase in potassium intake could be achieved by substituting potassium salts for sodium chloride in bread.

The effect of coffee-drinking on blood composition was studied in 20 healthy volunteers who normally consumed, on average, 560 mg caffeine/day from tea and coffee. After 14 days on decaffeinated coffee (12 mg caffeine/day) there was a reduction in blood glucose, a small rise in plasma cholesterol and phospholipid, and a more substantial fall in triglycerides. The substitution of coffee for decaffeinated coffee (875 mg caffeine/day) for 20 days did not affect blood glucose, but the changes in the plasma lipids were reversed. There was no change in the level of immunoreactive insulin, in platelet adhesiveness, fibrinogen or blood clot lysis time during the course of the experiment. The part played by caffeine and by coffee solids other than caffeine in the induction of these changes does not support the hypothesis that the consumption of coffee is a significant factor in the development of coronary heart disease.

~Children (227), aged 7-12 years, weighed and recorded all food and drink consumed for seven consecutive days. Each child completed tests of verbal and non-verbal intelligence, and was then randomly allocated to one of two groups after matching for age, sex, IQ and height. In a double-blind trial lasting for 28 d, one group received a vitamiwmineral supplement daily and the other group a placebo. On re-testing, there were no significant differences in performance between the two groups. Furthermore, there were no consistent correlations between test scores and micronutrient intakes based on the weighed records. Thus, we found no evidence that learning ability in a cross-section of British schoolchildren was limited by the quality of their diets. Diet: Intelligence : Vitamin-mineral supplementation : Schoolchildren Nutrient deficiencies, whether dietary or metabolic in origin, have long been known to cause learning disabilities and cognitive disorders (Passmore & Eastwood, 1986), and a number of studies have shown the benefits of dietary supplements on mental function in underfed children. It was reported, for example, that thiamin supplements improved test scores in 9-to 19-year-old children living in an orphanage in Virginia (Harrell, 1946). Pollitt ef al. (1985) presented results on the positive effect of iron supplements on cognitive performance in Egyptian children with anaemia (mean age 9-5 years), while Walter et al. (1983) showed similar effects in infants aged 15 months in whom haemoglobin levels were normal but other biochemical indicators of Fe status were low. The benefits of a supplement (energy, protein, vitamins and minerals) on the cognitive competence of infants born into poverty in Bogota, Colombia were demonstrated by Waber et al. (1981), in a prospective study lasting 3-5 years. Likewise, Barrett & Frank (1987) showed that the provision of a broad-based supplement to Guatemalan children aged 6-8 years with mild to moderate protein+nergy malnutrition resulted in improved mental test scores. In all these studies, however, evidence of undernutrition, obtained principally from anthropometric or biochemical measurements, was unequivocal. In the last two studies mentioned, the authors concluded that the effect of deprivation was to decrease motivation and arousal rather than to limit cognitive development per se, and that the benefits of supplementation diminish with increasing age.A recent paper on the effect of vitamin and mineral supplementation in British schoolchildren purported to demonstrate that in 12-to 13-year-old children with apparently normal growth and no clinical signs of nutrient deficiency, additional vitamins and minerals had a positive effect on performance in tests of non-verbal intelligence (Benton & Roberts, 1988). This is a surprising and potentially important finding. While there is a significant proportion of British schoolchildren who fail to meet the recommended daily allowance (RDA) for one or more of the micronutrients (Department of Health and Social Security, availa...

The response to the covert removal of around 500 kcal/d from the food of 10 healthy free-living male volunteers was measured over 10 days. A similar amount of energy was added to the food of four subjects. Normal food and drink was available ad libitum, and adjustments in food energy were made by the interchange of sugar and artificial sweeteners. Compensation for the theoretical energy deficit or surplus was incomplete, averaging around 50%. This, however, was very variable, some subjects achieving more than 90% recovery, whereas others failed completely to adjust energy intake within this timespan. It is concluded that the regulation of energy balance in the lean is a long-term phenomenon, conditioned by large day-to-day fluctuations in energy intake. The removal of sugar from the food raised the energy density of the diet. The substitution of artificial sweeteners for sugar caused an increase of 11% in total fat intake. The restoration of sugar had an opposite effect. This inverse relationship between dietary sugar and fat poses problems for those seeking to lose weight, and for the lean attempting to follow current guidelines for a 'healthier' diet without incurring weight loss.

1. Additional protein given to malnourished rats early in pregnancy was found to increase substantially the weight and cellularity of their foetuses and placentas at term.2. This observation confirms the hypothesis that protein is stored in early pregnancy for use during the period of rapid foetal growth.

The proportion of long-chain polyunsaturated derivatives of linoleic and linolenic acids in the erythrocyte lipids of infants fed a cow's milk formula was lower than in breast-fed infants. Although the formula provided only 0.55 % of the total energy as linoleic acid, essential fatty acid deficiency was not detected; the triene: tetraene ratio was 0.09.Essential fatty acid (EFA) deficiency can be recognized by changes of the proportions C, -, , polyunsaturated fatty acids in tissue lipids. Neither linoleic acid (18:zw6) nor alinolenic acid (18 : 303) can be synthesized by mammalian cells. Both can, however, undergo chain elongation and desaturation in animal tissues to give rise to two separate series of C,,-,, polyunsaturated fatty acids, the 06 and w3 series, derived from linoleic and a-linolenic acids respectively; no interconversion occurs between the two series (Holman, 1970). in length and in weight were identical with those of twenty wholly breast-fed infants, the normal decline in energy intake in relation to body-weight was noted, and clinical signs of linoleic acid deficiency were not observed. Analysis of the total plasma lipids for fatty acids showed that, although the triene: tetraene ratio did not approach the critical value of 0.4, the proportion of arachidonic acid was approximately half that found in breast-fed infants. The LCP derivatives of a-linolenic acid were not estimated.

I. The fatty-acid composition of the plasma total lipids of children with kwashiorkor and of healthy infants was determined by gas-liquid chromatography. Breast milk from Yoruba mothers, and traditional weaning foods, were also analysed for fatty acids, and for protein, fat and carbohydrate.z. Evidence of essential fatty acid (EFA) deficiency was obtained in the children with kwashiorkor. The proportions of linoleic and arachidonic acids were reduced in the plasma lipids, whereas the endogenous eicosatrienoic acid showed a marked increase. The triene: tetraene ratio had the abnormally high value of 1.08. These changes were consistent with the prolonged ingestion of suboptimal amounts of linoleic acid.3. Breast milk was of good quality, with a particularly high concentration of retinol. The milk was also rich in linoleic acid, and was thus discounted as a factor in the development of EFA deficiency, but the weaning foods were found to provide substantially less than the minimum recommended intake of I % of the total energy as linoleic acid. 4.The maize pap with which the children with kwashiorkor had been fed for several months before the appearance of acute symptoms provided almost 7 % of the energy as protein, but only 1.21 MJ (290 kcal)/kg. To satisfy energy requirements, it would have been necessary to consume 3-4 kg of the pap each day.5. I t is concluded that the protein deficiency which leads to the development of kwashiorkor in the Yoruba community arises from a very severe restriction in energy intake rather than from the consumption of foods very low in protein at adequate or excessive levels of energy intake.The development of kwashiorkor has long been attributed to the consumption of diets low in protein and rich in carbohydrate (Brock & Autret, 1952). The lack of fat in such diets, though occasionally remarked upon (Bronte-Stewart, 1961), has not, however, been considered as an important dietary factor in the aetiology of the disease. The human infant, like the young of other species, has been shown to have a requirement for fat by virtue of its content of linoIeic acid -the essential fatty acid (EFA). Wiese, Hansen & Adam (1958) noted that a diet providing I % of the total energy as linoleic acid was just adequate to prevent the clinical manifestations of EFA deficiency, and concluded, on the basis of measurements of serum fatty acid ratios, that optimum consumption would represent 4 % of the energy intake.In the infant with kwashiorkor, a deficiency of linoleic acid might have arisen in a number of ways: in the preweaning period from inadequate nutrition of the mother, resulting in the secretion of milk with a low concentration of linoleic acid, or, in the postweaning period, from feeding the children on traditional infant foods low in fat, or from an impaired absorption of fat. 1964).