Rheumatoid arthritis (RA) is characterized by inflammation of the synovial tissues in the joints. A number of papers related to dietary components that are associated with this inflammation are reviewed. In addition, the ecological approach is used to study the links between diet and RA. Multi-country data for prevalence of RA for females from eight and fifteen countries were compared statistically with components of national dietary supply. Fat from meat and offal for the period 2 years before the prevalence data was found to have the highest statistical association with the prevalence of RA (r2 0·877, P<0·001 for eight countries). The statistical correlations for meat and offal were almost as high as those for their fat. Similar correlations were found for temporal changes in indices of effects of RA in several European countries between 1968 and 1978 as more meat was added to the national diets, although the correlations were higher for meat than for fat. It is hypothesized that meat and offal may be a major factor contributing to the inflammation in RA. In the present short review, the author examines some of the data that associate meat consumption with RA and the possible factors, e.g. fat, Fe and nitrite, which may contribute to the inflammation.

The effect of two levels of dietary protein energy, moderate (20 %; MP) and high (70 %; HP), on urea kinetics in eleven domestic cats was studied. After a 3-week prefeed, a single dose of [15N15N]urea was administered, and urine and faeces collected over the subsequent 5 d. For each 24 h period, total urea and enrichment of [15N15N]- and [15N14N]urea in urine were determined, and a model applied to calculate urea production, entry into the gastrointestinal tract, recycling to urine or faeces and, by difference, retention by the body and potentially available for anabolism. Urea production and excretion increased with dietary protein level (P<0·05). Most of the urea produced was excreted, with only a small proportion entering the gut, and with the pattern of urea disposal not significantly different between the HP and MP diets. Thus, the percentages of urea production available to the gut were 15 % (MP) and 12 % (HP), of which 57 % (MP) and 59 % (HP) was recycled in the ornithine cycle, 40 % (MP and HP) was potentially available for anabolism and the rest lost as faecal N. As a percentage of urea produced the amount potentially available for anabolism was very low at 6·41 % (MP diet) and 4·79 % (HP diet). In absolute terms urea entering the gut, being recycled in the ornithine cycle and potentially available for anabolism was significantly higher on the HP diet (P<0·05). These results show that cats operate urea turnover, but at a lower rate, and with less nutritional sensitivity than has been reported for other species.

The objectives of this study were to confirm the non-absorbability and the reproducibility of faecal excretion kinetics of orally administered rare earth elements, and to investigate the excretion profiles of rare earth elements and stable isotopic tracers of Fe and Zn to establish the extent to which rare earth element markers duplicate the behaviour of isotopic tracers. Two investigations were performed: (1) six healthy subjects consumed a solution containing five rare earth elements in amounts varying from 1 to 10 mg; (2) seven healthy subjects were given a standard solution labelled with Sm marker and 57Fe tracer, and a meal labelled with Yb marker and 58Fe and 70Zn tracers. Individual faecal samples were collected and analysed to determine recoveries of rare earth elements and unabsorbed isotopic tracers. The mean values for recoveries were 94·1 (SD 4·5) % FOR THE FIVE RARE EARTH ELEMENTS, AND 103 (sd 3·0) % and 99·8 (sd 2·8) % for Sm and Yb respectively. For Fe consumed with the solution, excretion kinetics of the rare earth element marker and unabsorbed tracers with cumulative collections of the first two and three faecal samples were identical, but endogenous excretion of Fe was significant (P<0·05) in stools collected after the third. For Fe and Zn consumed with the meal, the excretion kinetics for the first two individual faecal samples and composites of sequential outputs were identical. Rare earth elements can be used as markers in studies of measurement of absorption. The dose of tracer required for the measurement of absorption would be reduced proportionally to the reduction of the period of faecal sampling, so that studies with stable isotopes would be more economical, thus enabling epidemiological investigations.

Rainbow trout (Oncorhynchus mykiss) hepatocytes were cultured under simulated conditions of varying nutritional status to explore the short-term modulation by dietary substrates of the main lipogenic enzymes: glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME), ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACoAC) and fatty acid synthetase (FAS). Primary cultures were individually exposed to varying amounts of glucose, hydrolysed casein and long-chain polyunsaturated fatty acids (PUFA) for 12 h. A second set of experiments was designed to evaluate the effects of mixing different relative amounts of these macronutrients in the culture medium. Glucose concentrations of up to 20–25 mM SHOWED A STIMULATORY EFFECT ON G6PD, ME, ACL AND ACOAC ACTIVITY (P<0·05) WHILE AN EARLIER INHIBITORY EFFECT ON FAS WAS OBSERVED AT 10–20 Mm glucose (P<0·05). The use of hydrolysed casein as a nutritional source of amino acids inhibited the activity of FAS and ME (P<0·05), and stimulated G6PD, ACoAC and ACL activity (P<0·05). Low levels of linolenic acid exerted a stimulatory effect on all the lipogenic enzymes assayed (P<0·05) with the exception of FAS, and increased amounts showed some inhibition of lipogenic activities (P<0·05). Eicosapentaenoic acid and docosahexaenoic acid showed a similar effect, although the former strongly inhibited FAS activity while the latter showed greater potential to inhibit ACoAC and G6PD. A complete change in the relative levels of glucose, hydrolysed casein and PUFA in turn led to changes in the enzyme activity patterns observed. The present study shows the feasibility of exploring the direct regulation of lipogenesis in isolated fish cells by varying the relative amounts of main macronutrients, mimicking in vivo dietary conditions. It is felt that such an approach may serve to investigate the macronutrient regulation of other metabolic pathways.

The kinetics of allantoin metabolism were studied in rumen-cannulated sheep by means of a single intravenous injection of [4,5-14C]allantoin. The decline in the specific radioactivity of allantoin in plasma following the injection of tracer was best described by a double exponential function, indicating that allantoin moves in and out of two or more kinetically distinct compartments. Sequestering of tracer in secondary or tertiary compartments in the body water appears likely to have resulted in overestimation of net flux of allantoin through the blood in the present study. In future studies, sampling of blood for several days after administration of tracer should alleviate this problem. About 80 % of the [14C]allantoin injected was recovered as [14C]allantoin in urine during the 12 h after tracer injection, increasing to 94 % after 4 d. Allantoin-C also passed through the blood bicarbonate pool, suggesting that allantoin is degraded in the gastrointestinal tract. A small amount of allantoin-C (4 % of the net flux of allantoin through the blood pool) was apparently degraded to form bicarbonate-C in the rumen and postruminally, and subsequently appeared in blood bicarbonate-C. Transfer of allantoin-C into the rumen via saliva was insignificant. In view of these findings, the net flux of allantoin through the blood should be a better predictor of rumen microbial outflow than urinary allantoin excretion, because urinary excretion of purine derivatives must be adjusted for conversion of allantoin-C to blood bicarbonate when used to predict the flow of microbial protein from the rumen.

The role of dietary fibres in colon carcinogenesis is controversial. To elucidate the mechanisms by which different dietary fibre sources may affect colonic tumour development, we studied the effects of diets enriched with cereal brans or inulin on protein kinase C (PKC) activity and isozyme expression in rat colon. Male Wistar rats (twelve per group) were fed one of the following AIN-93G-based diets () for 4 weeks: a non-fibre high-fat diet or one of the four high-fat diets supplemented with either rye, oat or wheat bran or inulin at 100 g/kg diet. The fat concentration (20 g/100 g) and fatty acid composition of the non-fibre high-fat diet was designed to approximate that in a typical Western-type diet. In the proximal colon, rats fed the inulin diet had a significantly higher membrane PKC activity and a higher membrane PKC δ level than rats fed the non-fibre diet (P<0·05). In the distal colon, rats fed the inulin and oat bran diets had a higher total PKC activity and a higher membrane PKC β2 level than rats fed the wheat-bran diet. Rats in the non-fibre and wheat-bran groups had the lowest concentrations of luminal diacylglycerol. In conclusion, feeding of wheat bran resulted in low distal PKC activity and expression of PKC β2, a PKC isozyme related to colonic cell proliferation and increased susceptibility for colon carcinogenesis, which may explain in part the protective effect of wheat bran against tumour development in a number of experimental colon cancer studies. The increase in PKC activity and PKC β2 expression by feeding inulin may be a drawback of inulin as a functional food.

This investigation was designed to estimate the Co requirement of growing cattle on the basis of plasma and liver levels of vitamin B12 and folate, plasma levels of homocysteine and methylmalonic acid (MMA) and haematological variables. For this purpose thirty-four male intact cattle of the German Simmental breed (236 kg) were assigned randomly to ten groups and were fed corn silage-based diets which contained 70, 90, 109, 147, 184, 257, 327, 421, 589 or 689 μg Co/kg DM for 40 weeks. One-slope broken-line model analysis and a quadratic model with plateau were used to estimate the Co requirement. The broken-line model estimated the dietary Co requirement of growing cattle to be 257 (SE 29) ΜG/KG DIETARY DM BASED ON PLASMA VITAMIN B12 AS RESPONSE CRITERION. THE DIETARY CO LEVELS NEEDED TO MAXIMISE THE LIVER VITAMIN B12 AND LIVER FOLATE WERE 236 (se 8) and 190 (se 8) μg/kg dietary DM respectively. Plasma folate did not show any response to the different Co levels. The dietary Co was inversely correlated with the plasma concentrations of homocysteine and MMA. Estimates of the dietary Co concentration required to minimise homocysteine were 161 (se 10) μg/kg DM. When MMA was used as response criterion, the linear model yielded a Co requirement of 124 (se 3) μg/kg dietary DM. The quadratic model did not provide a better closeness of regression fit and yielded similar requirements to the linear model. Haemoglobin concentration and haematocrit tended to have a slight response to increasing dietary Co and were only decreased in cattle on diets containing less than 100 μg Co/kg DM. On the basis of the present data, recommended levels of dietary Co for normal folate metabolism and minimum homocysteine and MMA levels can be set to be 150–200 μg/kg DM; for maximum vitamin B12 levels, the desired Co content in the diet seems to be 250 μg/kg DM.

We previously demonstrated that feeding a highly fermentable and water-soluble dietary fibre, guar-gum hydrolysate (GGH) increased intestinal absorption of insoluble Ca salts in total-gastrectomized rats. In the present study, we examined the effects of feeding a less fermentable and water-soluble fibre, polydextrose (PD), on Ca absorption and bone mineralization in the normal and total-gastrectomized rats in comparison with the effects of GGH. Apparent Ca absorption was severely lowered by gastrectomy, and PD feeding (50 g/kg diet) partially restored the reduction of Ca absorption similarly to GGH feeding (50 g/kg diet). PD feeding also increased the Ca absorption in normal rats, but not GGH feeding. Femur Ca concentration was reduced with gastrectomy. Feeding PD for 21 d increased the bone Ca concentration in both normal and gastrectomized rats, but GGH feeding did not. In rats fed PD, pH of the caecal contents was lower than in rats fed fibre-free and GGH diets; however, soluble Ca concentration in the caecal contents was not different between the diet groups. Short-chain fatty acid concentrations were much lower in the PD groups than in the GGH groups. We also examined in vitro Ca absorption by using everted sacs of the small intestine. Addition of PD to the serosal medium of the ileal sacs increased Ca absorption, but addition of GGH did not. These results suggest that the small intestine rather than the large intestine is responsible for the increase in Ca absorption in rats fed PD, and suggests that the mechanism for the increase by PD may be different from that by GGH.

The time course of changes in tissue lipolytic activities was studied in young rats during the consumption of a low-protein diet containing 50 g protein/kg (40 g wheat gluten +10 g casein/kg) for 28 d followed by balanced refeeding with 200 g protein/kg (160 g wheat gluten +40 g casein/kg) for 28 d. Lipoprotein lipase (LPL) activities were compared with the values of a control group fed a balanced diet containing 200 g protein/kg for 56 d. At the end of protein malnutrition period, the epididymal fat tissue LPL activity represented 36 %, and that of heart and gastrocnemius was 44 %, of those of the control group. These differences were accompanied by lower serum- and VLDL-triacylglycerols (TAG), respectively 47·6 % and 31 % of the control group values, probably resulting from reduced synthesis of VLDL-apolipoproteins (29 % of control group values), concomitant with liver lipid accumulation (4·8-fold) and little lipid storage in epididymal fat tissue. At day 2 of refeeding, there was no significant difference in liver and epididymal fat tissue LPL activities between experimental and control rats. At the end of the refeeding period, LPL activity of epididymal fat and liver lipolytic activity had increased and became similar to control group values. The consumption of a low-protein diet prevented the increase in extrahepatic LPL activities as observed in the control group. The alterations in LPL activity suggest that a low-protein diet limits lipid storage in adipose tissue due to reduced serum VLDL-TAG availability.

The aims of the present study were to determine the level of (-)-epicatechin (EC) and its metabolites in rat plasma after oral administration of cocoa powder and to evaluate the protective effect of cocoa powder in terms of suppressing the oxidation of plasma components. Rats were orally administered 1 g cocoa powder/kg body weight, containing 7·80 mg EC, and their blood was collected before administration and at designated time intervals thereafter. The EC and its metabolites in plasma were treated with β-glucuronidase and/or sulfatase, then analysed by HPLC and by liquid chromatography–MS. Several EC-related compounds were detected in plasma such as free EC, and glucuronide, sulfate, and glucuronide–sulfate conjugates of non-methylated or methylated EC. All EC metabolites showed a maximum concentration in plasma at 30–60 min post-administration. Glucuronide conjugates of both non-methylated and methylated EC were found in high concentration in plasma. Moreover, administration of cocoa powder significantly reduced the accumulation of lipid peroxides in plasma and significantly reduced the consumption of α-tocopherol in plasma oxidized by treatment with 2,2′-azobis-(2-amidinopropane) dihydrochloride (AAPH (25 mmol/l)) or CuSO4 (100 μmol/l) compared with that in the case of plasma obtained before administration. The total EC concentration in plasma was negatively correlated with the level of accumulation of lipid peroxides in plasma oxidized by treatment with AAPH (25 mmol/l) and was positively correlated with the level of residual α-tocopherol in plasma oxidized by treatment with CuSO4 (100 μmol/l). These results indicate that EC in cocoa powder was absorbed from the digestive tract, that various conjugated forms of EC were generated in the digestive tract and distributed to the plasma, and that these enhanced the antioxidative activity of plasma.

Partially hydrogenated fish oil (PHFO) contains a high amount of trans fatty acids (TFA). Total hydrogenation results in a minimal amount of TFA, but a high content of very-long-chain saturated fatty acids (VLCSFA). Absorption and metabolism of VLCSFA from totally hydrogenated fish oil (THFO) were studied in rats. Groups of eight rats were fed one of four diets containing 40 g soyabean oil (SBO)/kg (low-fat diet), 150 g SBO/kg (SBO diet), 40 g SBO+110 g PHFO/kg (PHFO diet) or 40 g SBO+110 g THFO/kg (THFO diet) for 4 weeks. A lower absorption coefficient of the fat content was found in the THFO group (61 %) compared with the other groups (PHFO 95 %, SBO 99 %, low fat 98 %; P<0·05), which was mainly due to reduced absorption of VLCSFA. A reduced weight gain was found for the THFO group compared with the other groups, but this was only significant when compared with the SBO group (P<0·05). Faecal fat excretion (dry weight) was markedly increased in the THFO group (47 %), which was 2·4, 4·8 and 8·3 times higher compared with the groups fed PHFO, SBO and low-fat diets (P<0·05), respectively. Serum total cholesterol was reduced for the PHFO and THFO groups (P<0·05), whereas serum triacylglycerol was increased for the PHFO group compared with the other groups (P<0·05). Animals fed THFO diet had an increased content of 20:0 and 22:0 in the serum triacylglycerol fraction (P<0·05), whereas only 20:0 was increased in the serum phospholipid fraction (P<0·05). The low absorption coefficient of THFO must be considered if this fat is to be used for consumption by animals or man.

Portal appearance of short-chain fatty acids (SCFA) produced from fermentation of three different resistant starch (RS) sources (raw potato starch, high-amylose maize starch and retrograded high-amylose maize starch) was investigated in pigs. The catheterization technique coupled with determination of portal blood flow was used to estimate SCFA uptake by the colonic mucosa. Our hypothesis was that these three RS were not equivalent butyrate providers for the colonic mucosa and that butyrate uptake would therefore be different after in vivo fermentation of each starch. The starches induced different patterns of appearance of SCFA in the portal blood; raw potato starch was the only RS source to show a significant appearance of butyrate in the portal blood. Thus, uptake of butyrate by the colonic mucosa apparently differed between starches. This finding suggests that butyrate uptake does not only depend on the flow of butyrate appearing in the lumen. Indeed, for unexplained reasons, utilization of butyrate by the colonic mucosa appeared to be less efficient when the butyrate was produced from fermentation of potato starch than when it was produced from fermentation of the other RS sources.

We evaluated the effects of three levels of energy intake, 73 % (CON73), 81 % (CON81) and 100 % (CON100) of the ad libitum intake of the control diet, on skeletal muscle growth induced by functional overload in male rats. Unlike most previous studies which have employed chronic or acute food restriction where all nutrients are reduced in the diet, the present study tested the effects of energy deprivation as a single factor without inducing other nutritional deficiencies. Muscular growth of plantaris and soleus muscles was induced by removal of synergist gastrocnemius muscles in one hindlimb; muscles in the other leg were used as sham-operated intra-animal controls. After 30 d, rats on the energy-restricted CON73 and CON81 diets gained less weight and had smaller livers, kidneys, hearts and fat pads (epididymal, retroperitoneal and omental) than CON100 rats (P<0·05). They also had smaller sham-operated plantaris muscles (CON73 -13 %, CON81 -9 %) containing less total protein (CON73 -14 %; CON81 -10 %) than CON100 rats (P<0·05). However, the same measurements in overloaded plantaris muscles were similar among groups. Soleus muscle mass and protein contents were not significantly affected by energy restriction in our study. Percentage distributions of myosin heavy-chain isoforms (types I, IIa, IIx and IIb) were similar among rats in CON100, CON81 and CON73 groups for both plantaris and soleus muscles. We conclude that the growth reduction of plantaris muscle induced by energy restriction at 73 % and 81 % for 30 d was prevented by functional overload in male rats.

Scarcely-absorbed antioxidants might reach the large bowel and exhibit antioxidant activity, opposing the action of reactive O species by bacterial and cellular metabolism and thus contributing to protection from oxidative damage-induced gastrointestinal diseases. This study was carried out to evaluate the antioxidant activity in the faeces of a group of healthy subjects on a freely-selected diet, and to look for possible associations with the intake of some macro- and micronutrients and food groups. Fourteen subjects recorded their food intake three times for a period of 2 d, each time collecting all the faeces passed during the next 24 h. Total antioxidant activity (TAA; mmol 6-hydroxy-2,5,7,8 tetramethylchroman-2-carboxylic acid (Trolox)/kg) of faecal suspensions was measured using the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS•+) decolorisation assay. The average TAA value of faeces was 26·6 (SD 10·2) MMOL TROLOX/KG WET FAECES (RANGE 7·5–50·5). THE TOTAL AMOUNT OF ANTIOXIDANT EQUIVALENTS EXCRETED OVER 24 H, DERIVED BY MULTIPLYING THE TAA BY THE AMOUNT OF FAECES PASSED OVER 24 H, WAS 3·24 (sd 1·51) mmol Trolox (range 0·92–5·82) and this was significantly correlated with the average 24 h intake of coffee (P=0·002), red wine (P=0·034), and particularly to the sum of coffee and red wine (P<0·0001). In conclusion, the faeces of healthy subjects show detectable capacity to scavenge radical cations, suggesting that antioxidant activity occurs in the colonic lumen. Moreover, such activity seems at least in part to be related to dietary habits.

The aim of the present study was to assess the influence of age on plasma concentration of α-tocopherol, retinol and carotenoids with a special attention paid to natural differences in body composition. Forty healthy subjects were recruited: twenty were less than 35 years old and twenty above 60 years old. Males and females were equally represented in each age group. Subjects were kept in energy balance and received controlled diets for 36 h. Fat mass and fat-free mass were determined with the 180-enriched water dilution technique. Plasma vitamins A and E, and carotenoid levels were determined after 12 h fasting and were shown to be similar in women and men. Plasma α-tocopherol concentration increased with age (+44 % elderly v. young), and correlated with % fat mass and plasma cholesterol. After adjustment for plasma cholesterol, the effect of age and % fat mass disappeared. In contrast, plasma lycopene level was 2-fold lower in the elderly than in the young group, and was inversely correlated with fat mass. When lycopene values were adjusted for fat mass, the effect of age disappeared. These results suggest that plasma levels of vitamin E and lycopene differed in the two age groups and that differences in plasma cholesterol and fat mass might participate in such an effect. Short-term vitamin intake did not appear to influence plasma vitamin concentrations.

Food samples (n 114) were prepared from vegetables commonly eaten in Europe. The glycosidic forms of the phyto-oestrogens daidzein and genistein were extracted from the dried foods into aqueous methanol. The isoflavones were quantified by GC–MS after hydrolytic removal of any conjugated carbohydrate. Completeness of extraction and any procedural losses of the isoflavones were accounted for using synthetic daidzin (7-O-glucosyl-4′-hydroxyisoflavone) and genistin (7-O-glucosyl-4′5-dihydroxyisoflavone) as internal standards. Of the 114 foods assayed, at a limit of quantification of 0·1 μg/kg dry weight, forty-eight contained no detectable daidzein or genistein, forty-one contained less than 100 μg/kg of the two isoflavones combined and the remaining twenty-five contained more than this amount. Soyabean products contained between 470 and 1420 mg (average of 960 mg) daidzein and genistein combined per kg wet weight of food, and legumes contained between 20 and 5750 μg/kg wet weight of food, with an average of 620 μg/kg. Cooking by boiling in water caused a decrease in the daidzein and genistein content of food in twenty-four of twenty-eight foods. The extent of the decrease was variable and warrants further investigation. The present paper comprises the first comprehensive description of the content of daidzein and genistein in vegetables.

As there is a possibility that Se influences the growth of animals via thyroid hormone metabolism, the following three experiments were undertaken in order to determine the effects of dietary Se on growth, skeletal muscle protein turnover and thyroid hormone status in broiler chickens. Broiler chickens were raised on a Se-deficient diet until 12 d of age and then used for the experiments. In Experiment 1, twenty-eight birds were randomly assigned to four groups and fed purified diets with the following amounts of Se supplementation: 0·0, 0·1, 0·3 and 0·5 mg Se/kg diet. Dietary Se supplementation significantly increased plasma 3,5,3′-triiodothyronine (T3) concentration and improved growth, while plasma thyroxine (T4) concentration was decreased. In Experiment 2, twenty-eight birds were assigned to four groups and fed either a Se-deficient diet or a Se-supplemented diet (0·3 mg Se/kg diet) with or without the supplementation of iopanoic acid, a specific inhibitor of 5′-deiodinase (5 mg/kg diet). The growth was promoted and feed efficiency was improved by dietary Se supplementation as was also observed in Experiment 1. However, this effect of Se was halted by iopanoic acid supplementation. Hepatic 5′-deiodinase activity was elevated by Se and inhibited by iopanoic acid. In Experiment 3, birds were fed on the following diets to show that Se influences growth of birds via thyroid hormone metabolism: Se-deficient diet, Se-supplemented diets (0·1 and 0·3 mg/kg) and T3 supplemented diets (0·1 and 0·3 mg/kg diet). Lower dietary T3 supplementation (0·1 mg/kg diet) resulted in growth promotion similar to Se supplementation, while higher level of T3 caused growth depression. Furthermore, it was observed that the rate of skeletal muscle protein breakdown tended to be increased by Se similarly to the effect of T3. In conclusion, it was shown in the present study that Se deficiency depresses growth of broilers by inhibiting hepatic 5′-deiodinase activity which causes lower plasma T3 concentration.

Aliphatic dioic acids have been proposed as alternative nutrients in selected clinical situations. In this study, their possible insulinotropic action was investigated in isolated rat pancreatic islets prepared from fed rats. Azelaic acid, sebacic acid and tridecanedioic acids, when tested at a 10·0 mM CONCENTRATION, WERE FOUND TO AUGMENT INSULIN RELEASE EVOKED BY d-glucose (7·0 mm) in the pancreatic islets. Likewise, glycerol-1,2,3-tris(dodecanoedioate), when used at concentrations close to 1·0 mm, increased the secretory response to the hexose. It is speculated that these findings may extend to insulin-producing cells, the knowledge that aliphatic dioic acids or their esters may act as energy substrates, e.g. in parenteral nutrition.

It was previously shown that a high plasma concentration of non-esterified fatty acids (NEFA) persisted after a fatty breakfast, but not after an isoenergetic carbohydrate breakfast, adversely affecting glucose tolerance. The higher concentration after the fatty breakfast may in part have been a result of different mobilization rates of fatty acids. This factor can be investigated as NEFA mobilized from tissues are monounsaturated to a greater extent than those deposited from a typical meal. Twenty-four middle-aged healthy Caucasian men were given oral glucose tolerance tests (OGTT), and for 28 d isoenergetic breakfasts of similar fat composition but of low (L) or moderate (M) fat content. The composition of NEFA in fasting and postprandial plasma was determined on days 1 and 29. No significant treatment differences in fasting NEFA composition occurred on day 29. During the OGTT and 0–1 h following breakfast there was an increase in plasma long-chain saturated NEFA but a decrease in monounsaturated NEFA (μg/100 μg total NEFA; P<0·001). Between 1 and 3 h following breakfast treatment differences occurred for total saturated and total monounsaturated fatty acids (μg/100 μg total NEFA; P<0·05), expressed as an increase in 18 : 1 and decreases in 16 : 0 and 17 : 0 in treatment M relative to treatment L (P<0·05). Serum insulin attained 35 and 65 mU/l in treatments M and L respectively during this period. Negative correlations were found between 16 : 0 in fasting plasma and both waist:hip circumference (P=0·0009) and insulin response curve area during OGTT (within treatment M, P=0·0001). It is concluded that a normal postprandial insulin response is associated with a rapid change in plasma saturated:monounsaturated NEFA. It is proposed that this change is the result of a variable suppression of fat mobilization, which may partly account for a large difference in postprandial total plasma NEFA between fatty and carbohydrate meals.