Phyto-oestrogens have emerged from their esoteric role in animal husbandry following the hypothesis that the human Western diet is relatively deficient in these substances compared with societies where large amounts of plant foods and legumes are eaten. Evidence is beginning to accrue that they may begin to offer protection against a wide range of human conditions, including breast, bowel, prostate and other cancers, cardiovascular disease, brain function, alcohol abuse, osteoporosis and menopausal symptoms. Of the two main classes of these weak oestrogens, the isoflavones are under intensive investigation due to their high levels in soyabean. Like the ‘anti-oestrogen’ Tamoxifen, these seem to have oestrogenic effects in human subjects in the cardiovascular system and bone. Although previously only available from food, isoflavones are now being marketed in health-food supplements or drinks, and tablets may soon be available over the counter as ‘natural’ hormone-replacement therapy. In cancer, anti-oestrogenic effects are thought to be important, although genistein especially has been shown to induce wide-ranging anti-cancer effects in cell lines independent of any hormone-related influence. There are few indications of harmful effects at present, although possible proliferative effects have been reported. In infants, the effects of high levels in soya milk formulas are uncertain. The second group, lignans, have been less investigated despite their known anti-oestrogenic effects and more widespread occurrence in foods. Investigation of the possible benefits of phyto-oestrogens is hampered by lack of analytical standards and, hence, inadequate methods for the measurement of low levels in most foods. This problem may prove to be a major dilemma for regulatory authorities, clinicians and others wishing to advise the general public on whether these compounds really do have the health benefits attributed to them.

The role of maternal diet in the development of the fetal brain has not been adequately explored. Marine n-3 fatty acids have, however, been proposed to be important for brain development. The present case–control study aimed to investigate the relationship between dietary intake during pregnancy and the occurrence of cerebral palsy (CP) in the offspring. Children with CP (n 109), born between 1984 and 1988 to mothers residing in the Greater Athens area, were identified at any time in 1991 or 1992 through institutions delivering care and rehabilitation. Successful nutritional interviews were conducted with ninety-one of these children. Controls were chosen among the neighbours of the CP cases or were healthy siblings of children with neurological diseases other than CP, seen by the same neurologists as the children with CP. A total of 278 control children were chosen, and 246 of them were included in the nutritional study. Guardians of all children were interviewed in person on the basis of a questionnaire covering obstetric, perinatal socioeconomic and environmental variables. A validated semiquantitative food-frequency questionnaire of 111 food items was used to estimate maternal dietary intake during pregnancy. Statistical analysis was done by modelling the data through logistic regression. Food groups controlling for energy intake were alternatively and simultaneously introduced in a core model containing non-nutritional confounding variables. Consumption of cereals (mostly bread) and fish intake were inversely associated with CP (P < 0·05 and P < 0·09 respectively) whereas consumption of meat was associated with increased risk (P < 0·02). A protective effect of fish consumption and a detrimental effect of meat intake have been suggested on the basis of earlier work and appear to be biologically plausible. If corroborated by other studies, these results could contribute to our understanding of the nutritional influences on fetal brain development.

The aim of the present study was to evaluate changes in participation in physical activity and in fat and alcohol intake associated with ageing. This issue was examined in adults (n 207) who were tested between 1978 and 1982 and re-tested 12 years later. These adults were 42.3 (sd 4.9) years of age at baseline. Their children (n 122) were tested over the same follow-up period. They were, on average, 12.5 (sd 1.9) years at entry into the study. A decrease in the proportion of daily energy intake as fat and an increase in participation in vigorous physical activities were observed over the 12-year period in both groups. The proportion of dietary energy as alcohol remained stable in adults whereas it increased markedly in children. Correlation analyses between baseline and follow-up levels were significant for dietary fat and alcohol intake in adults. In children, the levels of these variables in the growing years did not predict the levels attained 12 years later. Even though the adults displayed changes in fat balance generally following current public health recommendations, a substantial increase in skinfold thicknesses was observed in these subjects during follow-up. This observation suggests that there is a strong effect of age-related factors on fat balance.

Epidemiological evidence shows that a diet high in monounsaturated fatty acids (MUFA) but low in saturated fatty acids (SFA) is associated with reduced risk of CHD. The hypocholesterolaemic effect of MUFA is known but there has been little research on the effect of test meal MUFA and SFA composition on postprandial lipid metabolism. The present study investigated the effect of meals containing different proportions of MUFA and SFA on postprandial triacylglycerol and non-esterified fatty acid (NEFA) metabolism. Thirty healthy male volunteers consumed three meals containing equal amounts of fat (40g), but different proportions of MUFA (12, 17 and 24% energy) in random order. Postprandial plasma triacylglycerol, apolipoprotein B-48, cholesterol, HDL-cholesterol, glucose and insulin concentrations and lipoprotein lipase (EC 3.1.1.34) activity were not significantly different following the three meals which varied in their levels of SFA and MUFA. There was a significant difference in the postprandial NEFA response between meals. The incremental area under the curve of postprandial plasma NEFA concentrations was significantly (P = 0·03) lower following the high-MUFA meal. Regression analysis showed that the non-significant difference in fasting NEFA concentrations was the most important factor determining difference between meals, and that the test meal MUFA content had only a minor effect. In conclusion, varying the levels of MUFA and SFA in test meals has little or no effect on postprandial lipid metabolism.

Previous studies have noted the presence of an early postprandial peak in plasma triacylglycerol concentrations following successive fat-rich meals. An earlier study has shown that the triacylglycerol in this early peak originates from a previous meal. The present study was performed to investigate the effects of different second meals on the plasma triacylglycerol response. Six healthy subjects were studied on four occasions each. At 5 h following a fat-rich breakfast they ingested one of the following in a balanced design: a fat-rich meal, a low-fat meal, water or nothing by mouth. Blood samples were taken for 2.5 h following the second meal. An early peak in chylomicron and plasma triacylglycerol concentrations was seen following both low-fat and fat-rich second meals but not following water. During studies investigating postprandial lipaemia, further meals must be avoided, even if they contain no fat, although water may be allowed.

The aim of the present investigation was to study the relationship between ascorbic acid status during the third trimester of pregnancy and levels of this vitamin in transition milk (days 13–14 of lactation) and mature milk (day 40 of lactation). To this end, the pregnancies and lactation periods of fifty-seven healthy women between 18 and 35 years of age (27 (sd 3.7) years) were monitored. Vitamin intake during the third trimester was determined by recording the consumption of foods over 5 d, and by registering the quantities provided by dietary supplements. Ascorbic acid levels in maternal serum during this stage of pregnancy, and in transition and mature milk samples, were determined by spectrophotometry. Those subjects with ascorbic acid intakes below that recommended (80 mg/d) (group L) showed lower consumption of fruit and vegetables than did those with greater intakes (group H). The consumption of ascorbic acid supplements was very low, and was only seen in three group H subjects. The difference in ascorbic acid intake was reflected at serum level. Group L subjects showed significantly lower serum values than did group H subjects (30.1 (sd 36.3) μmol/l compared with 101.1 (sd 168.1) μmol/l). Vitamin intake also influenced the composition of transition milk. Group L subjects showed significantly lower levels of ascorbic acid in milk than did group H subjects (255.5 (sd 220.3) μmol/l compared with 437.8 (sd 288.4) μmol/l). The results of the present study reveal the need to increase the consumption of fruits and vegetables during pregnancy and to monitor maternal ascorbic acid intake and vitamin C status.

Fluoxetine is one of the most widely used antidepressants and nowadays it is also being used to manage obesity problems. In our laboratory we demonstrated that the drug inhibited sugar absorption (Monteiro et al. 1993). The aim of the present work was to determine the effect of fluoxetine on intestinal leucine absorption. Using a procedure of successive absorptions in vivo the drug diminished amino acid absorption by 30% (P < 0.001). Experiments in vitro in isolated jejunum also revealed a reduction in leucine uptake of 37% (P < 0.001). In both cases fluoxetine only affected mediated transport without altering diffusion. In a preparation enriched in basolateral membrane, fluoxetine inhibited the Na+,K+-ATPase (EC 3.6.1.37) activity (55%; P < 0.001) in a non-competitive manner with an inhibition constant (Ki) value of 0.92 mm. Leucine uptake by brush-border membrane vesicles was diminished by the drug (a reduction of 48% was observed at 30s, P < 0.001); only the apical Na+-dependent transport system of the amino acid was modified and the inhibition was non-competitive. Leucine uptake in the presence of lysine indicated that transporter B was involved. These results suggest that fluoxetine reduces leucine absorption by its action on the basolateral and apical membrane of the enterocyte; the nutritional status of the patients under drug treatment may be affected as neutral amino acid absorption is decreased.

Effects of dietary protein restriction and ovariectomy on plasma concentrations and hepatic messenger RNA (mRNA) of insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding proteins (IGFBP) were investigated in young female rats. Ovariectomy increased plasma IGF-I concentration in rats fed on either a 50 g casein/kg diet (protein-restricted diet) or a 200 g casein/kg diet (control diet), but it increased IGF-I mRNA in liver only in the rats fed on the control diet. On the other hand, by Western ligand blot analysis, we observed that ovariectomy increased plasma IGFBP-3 concentration, and decreased plasma IGFBP-4 concentration. Ovariectomy did not affect IGFBP-1 and IGFBP-2 mRNA in liver, but dietary protein restriction significantly increased them, which may correspond to their plasma concentrations. The present results show that ovarian hormones and dietary protein content affect the plasma concentrations of IGF-I, IGFBP-3 and IGFBP-4 and hepatic mRNA of IGF-I, IGFBP-1, IGFBP-2, IGFBP-3 and IGFBP-4 in different manners.

Previous studies have described high plasma triiodothyronine (T3) concentrations and sympathetic activity in rats fed on low-protein diets. The present investigation examined how the nutritional status of rats fed on a low-protein diet was affected when these hormonal changes were reduced by drug administration. The low-protein diet (LP group) prevented growth, reduced plasma albumin levels, elevated plasma T3 concentration, and increased both the weight of the interscapular brown adipose tissue (BAT) and the activity of BAT cytochrome c oxidase (EC 1.9.3.1). Lowering the plasma T3 concentration (with carbimazole; CA group) elevated the plasma insulin concentration, promoted a small increase in the plasma albumin concentration and caused weight gain in comparison with the LP group. Reduction of sympathetic activity (with α-methyl-p-tyrosine; MT group) promoted a small elevation in plasma albumin concentration accompanied by a diminished T3 concentration, BAT weight, and an increase in fat deposition in relation to LP rats. In a second experiment, simultaneous lowering of the plasma T3 concentration and sympathetic activity (CA/MT group) resulted in weight gain associated with elevated plasma insulin concentration and fat deposition and a marked reduction in BAT cytochrome c oxidase activity. However no change in the hypoalbuminaemia was observed. The results of the present study suggest that in spite of the previously described increase in metabolic rate in rats fed on a diet with low-protein concentration when compared with controls, the mechanisms involved in the control of BAT activity and fat deposition seem to be independent of those which cause liver protein depletion and hypoalbuminaemia.

The effect of high- (hePE) and low- (lePE) esterification pectin and high- (hvGG) and low-(lvGG) viscosity guar gum on plasma, hepatic and biliary lipids and on prevention of cholesterol gallstones was investigated in male golden Syrian hamsters (Mesocricetus auratus). Hamsters were fed on cholesterol-rich (4g/kg), gallstone-inducing diets for 6 weeks. The diets were supplemented with 80g hePE, lePE, hvGG or lvGG/kg or 80g additional cellulose/kg. No significant differences in plasma total cholesterol and triacylglycerol concentrations between hvGG and lvGG and the gallstone-inducing or cellulose-enriched diets were observed. The hePE diet produced a 16% (non-significant) reduction in total plasma cholesterol but significantly decreased the plasma triacylglycerol level by 45%. The lePE diet caused only minor changes in plasma lipids. Hepatic cholesterol concentrations were significantly higher in hamsters fed on hvGG, lvGG, hePE or lePE primarily due to the accumulation of esterified cholesterol. Supersaturated bile samples, with lithogenic indices ranging from 1.6 to 2.0, were determined with all diets. The hePE and lePE diets slightly altered the bile acid profile by increasing glycocholic acid and decreasing taurochenodeoxycholic acid concentrations resulting in a higher cholic: chenodeoxycholic acid ratio. Cholesterol gallstone formation was not substantially inhibited by the two varieties of pectin and guar gum. The hvGG, lvGG, hePE and lePE diets did not alter faecal weight and caused only minor increases in faecal bile acid excretion. In general, the present findings demonstrate that dietary pectins and guar gums had only minor effects on cholesterol metabolism and did not prevent cholesterol gallstone formation in this hamster model. Possible explanations for this lack of a distinct response to pectin and guar gum are discussed.