Pathways from obesity to diabetes.

The relationship between obesity and type 2 diabetes has been known for decades and the recent important increase in such diseases represents a major medical problem worldwide. Several prospective studies present both impaired insulin release and insulin resistance as the major factors for the development of type 2 diabetes. The factor that dominates in obesity is the permanent elevation of plasma FFA and the predominant utilization of lipids by the muscle inducing a diminution of glucose uptake and, therefore, insulin resistance. The rise in insulin secretion appears to be a compensatory mechanism that responds to the increased levels of circulating glucose. The fall in insulin secretion occurs as a late phenomenon. The present review aims at analysing the mechanisms that lead human obesity to type 2 diabetes and using the pathophysiological information for the prevention of diabetes. The partial reversibility of the evolution of obesity towards diabetes is well demonstrated today by lifestyle changes and multidisciplinary weight loss programs.

Endogenous glucose production, gluconeogenesis and liver glycogen concentration in obese non-diabetic patients.

Resting, post-absorptive endogenous glucose production (EGP), fractional gluconeogenesis and liver glycogen concentration were assessed in 6 lean and 5 obese non-diabetic subjects undergoing elective abdominal surgery. During the 2 days preceding these measurements, 0.3 g/day U-13C glucose had been added to their usual diet to label their endogenous glycogen stores. On the morning of day 3, EGP was measured with 6,6-2H glucose. Their endogenous 13C glycogen enrichment was calculated from 13CO2 and respiratory gas exchanges. Fractional gluconeogenesis was assessed as 1-(13C glucose/13C glycogen)100. EGP was similar in lean subjects (113 +/- 5 mg/min) and in obese subjects (111 +/- 6). Fractional gluconeogenesis was higher in obese (59 +/- 10%) than in lean subjects (29 +/- 8%). However, overall EGP remained constant due to a decrease in glycogenolysis. Since an increased gluconeogenesis and a decreased glycogenolysis may both contribute to increase liver glycogen concentration in obesity, hepatic glycogen concentrations were assessed in hepatic needle biopsies obtained during surgery. Hepatic glycogen concentrations were increased in obese patients (515 +/- 38 mg/g protein) compared to lean subjects (308 +/- 58, p < 0.05). It is concluded that in obese patients: a) fractional gluconeogenesis is increased; b) overall EGP is unchanged due to a proportional inhibition of glycogenolysis; c) liver glycogen concentration is increased.

Effect of lipid oxidation on the regulation of glucose utilization in obese patients.

The effect of changes in lipid oxidation on glucose utilization (storage and oxidation) was studied in seven nondiabetic obese patients. They participated in three protocols in which: (1) Intralipid (to raise plasma FFA concentrations), (2) beta-pyridylcarbinol [a precursor of nicotinic acid, to lower plasma free fatty acids (FFA) concentrations], or (3) isotonic saline were infused over 2 h. Thereafter, these infusions were discontinued, and a 2-h euglycemic, hyperinsulinemic clamp was performed to measure glucose uptake. All studies were carried out in combination with indirect calorimetry to measure oxidative and nonoxidative glucose disposal (glucose storage). The high plasma FFA concentrations (1024 +/- 57 mumol/l) and lipid oxidation rates (1.1 +/- 0.1 mg/kg.min) found at the end of the Intralipid infusion and the low plasma FFA concentrations (264 +/- 26 mumol/l) and lipid oxidation rates (0.7 +/- 0.1 mg/kg.min) found at the end of the beta-pyridylcarbinol infusions resulted in significantly different rates of total and nonoxidative glucose disposal during the insulin clamp. The values were 2.6 +/- 0.6 mg/kg.min after Intralipid and 4.1 +/- 1.0 mg/kg.min after beta-pyridylcarbinol for total glucose disposal, and 0.4 +/- 0.4 and 1.6 +/- 0.8, respectively for nonoxidative glucose disposal. In conclusion, these observations show that changes in lipid oxidation rates preceding a glucose load influence glucose disposal and glycogen storage in obese subjects.

Regulation of nutrient metabolism and energy expenditure.

The requisites for energy expenditure are covered mainly by two major substrates, glucose and free fatty acids (FFA). Their regulation and metabolism differ. After carbohydrate ingestion, glucose is rapidly oxidized or stored in muscles and liver. There is a constant alternance between glucose storage as glycogen after meals and glycogen mobilization in the postabsorptive state when plasma glucose has returned to the basal state. Impairment of this alternance, in particular when glycogen stores are not being used, may lead to glucose intolerance and insulin resistance. Ingestion of lipids is not followed by an immediate increase in lipid oxidation, but FFA are stored as triglycerides in different tissues. Lipolysis occurs in the fasting state from tissue triglycerides and favors lipid oxidation. Lipid oxidation is typically increased in obesity. The preferential use of FFA from triglyceride stores for energy expenditure in obesity is responsible for the decrease in glucose mobilization from glycogen stores. This leads to a negative feedback of muscle and liver glycogen on glycogen synthase activity and consequently on glucose storage. It results in glucose intolerance after carbohydrate ingestion. Diabetes develops in obesity, usually after a long period of glucose intolerance, when glycemia does not return to the basal state. In obesity, glucose intolerance and insulin resistance can be prevented, or if already existing, can be decreased by stimulating glycogen mobilization by exercise, thermogenesis-stimulating drugs, and weight loss, which reduces fat stores and decreases lipid oxidation.

[From obesity to diabetes]. / De l'obesité au diabéte.

The frequent development of Type 2 diabetes in the obese suggests a relationship between obesity and diabetes. This study presents evidence for a continuum form obesity to diabetes via glucose intolerance and hyperinsulinemic diabetes. The defect which seems to be at the origin of this development resides in the increase in lipid oxidation already present in the early stages of obesity. It reflects the increased utilisation of fatty acids for energy purpose in the obese, at the expenses of glucose. In non-diabetic obese subjects, insulin resistance can be demonstrated by the inhibition of glucose storage during a euglycemic, hyperinsulinemic, clamp. This defect in glucose storage is not observed during a oral glucose tolerance test (OGTT), as it is compensated by hyperinsulinemia and hyperglycemia during glucose tolerance. Glucose tolerance appears with the inhibition of glucose oxidation by the augmented lipid oxidation. This decreased glucose utilization causes a slowdown of the utilization of glycogen stores which leads, as a consequence, to the inhibition of glycogen synthase by its product, glycogen. Diabetes appears when the increase in glycemia and insulinemia does not compensate any more for the inhibition of glucose storage. The rise in basal glycemia simultaneously with the fall in glucose storage corresponds to the transition to diabetes. The decreased glucose mobilization together with the inhibition of glycogen phosphorylase are such in the diabetic patient that glycogen stores tend to remain full and glycogen synthase is inhibited by negative feedback. The retrograde inhibition of glycogen stores on glycogen synthase activity brings up incapacity to store glucose and leads to a rise in glycemia. Finally, the evolution of obesity to diabetes leads to a decrease in insulin secretion with increase in hepatic glucose production through gluconeogenesis and decreased capacity to store glucose. Therapeutic implications are discussed in this review.

Effect of a novel beta-adrenoceptor agonist (Ro 40-2148) on resting energy expenditure in obese women.

The aim of this single-blind, placebo-controlled study was to investigate the effects of the new beta-adrenergic compound Ro 40-2148 on resting energy expenditure (REE) at rest and after an oral glucose load in non-diabetic obese women before and after two weeks of treatment. After one week of placebo administration and after an overnight fast and one hour rest, REE and glucose and lipid oxidation rates were measured by indirect calorimetry (hood system) before and for 6 h after a single dose of placebo solution. A 75 g oral glucose tolerance test (OGTT) was performed during this period starting 90 min after the placebo administration. During the following two weeks, using a randomization design, six patients received Ro 40-2148 at a dose of 400 mg diluted in 100 ml water twice a day (i.e. 800 mg per day), while six others continued with the placebo administration. The same tests and measurements were repeated after two weeks, except for the treatment group which received the drug instead of the placebo. The 14-day period of drug administration did not increase REE measured in post-absorptive conditions. Similarly, there was no acute effect on REE of a 400 mg dose of Ro 40-2148. In contrast, glucose-induced thermogenesis was significantly increased after two weeks in the treatment group (means +/- s.e.m.: 3.7 +/- 1.3%, P = 0.047), while no change was observed in the placebo group (-0.8 +/- 0.7%, not significant). Since there was no significant change in the respiratory quotient, the increase in energy expenditure observed in the treatment group was due to stimulation of both lipid and glucose oxidation. The drug induced no variations in heart rate, blood pressure, axillary temperature or in plasma glucose, insulin and free fatty acid levels. In conclusion, this study shows that Ro 40-2148 activates glucose-induced thermogenesis in obese non-diabetic patients.

Evolution from obesity to diabetes.

The relationship between obesity and Type 2 diabetes mellitus is so closely related that it is worth questioning the possibility of obesity being more than just one diabetes risk factor among others but a factor which participates causally to the development of Type 2 Diabetes on a genetic background. In this review, the evolution of normal glucose tolerance towards impaired glucose tolerance corresponds to the development of compensatory metabolic changes. These compensatory mechanisms are hyperinsulinaemia and postprandial hyperglycaemia which prevents a defect in glucose uptake and especially glucose storage. These compensatory responses are overcome with time and diabetes develops in spite of the hyperinsulinaemia and the hyperglycaemia. The capacity for glucose storage is decreased and cannot be overcome at this stage by increases of both glucose and insulinemic responses. Inhibition of glycogen synthase activity by an increased muscle glycogen concentration is probably more powerful than its stimulation by insulin and glucose and the capacity for glucose storage remains decreased. Finally with time insulin secretion gradually decreases as a consequence of chronic hyperglycaemia and results in full pancreatic decompensation. At this stage hepatic glucose production is increased. The most important factor in the evolution from obesity to diabetes reside in the permanence of the increase in lipid oxidation and mainly in the duration of obesity. An important consequence of permanently high lipid oxidation is the chronic resistance to glucose uptake, initially compensated for by increased plasma insulin and glucose concentrations. A vicious circle starts after insulin resistance to glucose uptake appears, followed by hyperglycaemia blocking the glucose storage system and by the lack of storing capacity leading to a rise in glycaemia. In conclusion, all these metabolic phenomena are appearing in a sequential way, progressively adapting to the deteriorating situation, through the stages of normal glucose tolerance, impaired glucose tolerance, hyperinsulinaemic and finally hypoinsulinemic diabetes.

Metabolic origin of insulin resistance in obesity with and without type 2 (non-insulin-dependent) diabetes mellitus.

A metabolic hypothesis is presented for insulin resistance in obesity, in the presence or absence of Type 2 (non-insulin-dependent) diabetes mellitus. It is based on physiological mechanisms including a series of negative feed-back mechanisms, with the inhibition of the function of the glycogen cycle in skeletal muscle as a consequence of decreased glucose utilization resulting from increased lipid oxidation in the obese. It considers the inhibition of glycogen synthase activity together with inhibition of glucose storage and impaired glucose tolerance. The prolonged duration of increased lipid oxidation, considered as the initial cause, may lead to Type 2 diabetes. This hypothesis is compatible with others based on the inhibition of insulin receptor kinase and of glucose transporter activities.

Correlations of glycogen synthase and phosphorylase activities with glycogen concentration in human muscle biopsies. Evidence for a double-feedback mechanism regulating glycogen synthesis and breakdown.

The purpose of this study was to verify in man the relationships of muscle glycogen synthase and phosphorylase activities with glycogen concentration that were reported in animal studies. The upper level of glycogen concentration in muscle is known to be tightly controlled, and glycogen concentration was reported to have an inhibitory effect on synthase activity and a stimulatory effect on phosphorylase activity. Glycogen synthase and phosphorylase activity and glycogen concentration were measured in muscle biopsies in a group of nine normal subjects after stimulating an increase of their muscle glycogen concentration through either an intravenous glucose-insulin infusion to stimulate glycogen synthesis, or an Intralipid (Vitrum, Stockholm, Sweden) infusion in the basal state to inhibit glycogen mobilization by favoring lipid oxidation at the expense of glucose oxidation. Phosphorylase activity increased from 71.3 +/- 21.0 to 152.8 +/- 20.0 nmol/min/mg protein (P < .005) after the glucose-insulin infusion. Phosphorylase activity was positively correlated with glycogen concentration (P = .005 and P = .0001) after the glucose-insulin and Intralipid infusions, respectively. Insulin-stimulated glycogen synthase activity was significantly negatively correlated with glycogen concentration at the end of the Intralipid infusion (P < .005). In conclusion, by demonstrating a negative correlation of glycogen concentration with glycogen synthase and a positive correlation with phosphorylase, this study might confirm in man the double-feedback mechanism by which changes in glycogen concentration regulate glycogen synthase and phosphorylase activities. It suggests that this mechanism might play an important role in the regulation of glucose storage.

Thermogenesis and fructose metabolism in humans.

Resting metabolic rate was measured in 10 healthy volunteers (25 yr, 73 kg, 182 cm) for 1 h before and 4 h during intravenous (iv) fructose administration (20% at 50 mumol.kg-1.min-1) with (+P) or without (-P) propranolol (100 micrograms/kg, 1 microgram.kg-1.min-1) during the last 2 h. Some subjects were studied a further 2 h with fructose infusion and +P or -P in hyperinsulinemic (2.9 pmol.kg-1.min-1) euglycemic conditions. Glucose turnover ([3-3H]glucose, 20 muCi bolus and 0.2 muCi/min) was calculated over 30 min at 0, 2, 4, and 6 h. The thermic effect of iv fructose was approximately 7.5% and decreased to 4.9 +/- 0.4% (P less than 0.01) +P. During the euglycemic clamp the thermic effect was 6.2 +/- 0.9% (-P) and 5.3 +/- 0.9% (+P). Hepatic glucose production (HGP) was 11.7 mumol.kg-1.min-1 (0 h) and did not change after 2 h iv fructose (11.8 +/- 0.5 and 9.8 +/- 0.6 mumol.kg-1.min-1 -P and +P, respectively) but increased to 13.8 +/- 0.9 (-P) and 12.9 +/- 0.8 mumol.kg-1.min-1 (+P) (P less than 0.01) after 4 h. HGP was suppressed to varying degrees during the euglycemic clamp. It is concluded that 1) the greater thermic effect of fructose compared with glucose is probably due to continued gluconeogenesis (which is suppressed by glucose or glucose-insulin) and the energy cost of fructose metabolism to glucose in the liver. 2) There is a sympathetically mediated component to the thermic effect of fructose (approximately 30%) that is not mediated by elevated plasma insulin concentrations similar to those observed with iv glucose.

Thermogenesis in obese women: effect of fructose vs. glucose added to a meal.

To assess the effect of a fructose meal on resting energy expenditure (EE), indirect calorimetry was used in 23 women (10 lean and 13 obese) for 30 min before and 6 h after the ingestion of a mixed meal containing 20% protein, 33% fat, and either 75 g glucose or 75 g fructose as carbohydrate source (47%). Expressed as a percentage of the energy content of the meal, the thermogenic response to the fructose meal was significantly greater (10.2 +/- 0.5%) than that of the glucose meal (8.4 +/- 0.4%, P less than 0.01). This difference was still apparent when the lean and obese women were considered separately. The mean respiratory quotient during the 6-h postprandial period was significantly greater (P less than 0.01) for the fructose (0.85 +/- 0.01) than for the glucose meal (0.83 +/- 0.01) in the combined subjects. In addition, cumulative carbohydrate oxidation was significantly greater after the fructose than after the glucose meal (51.1 +/- 2.3 vs. 40.9 +/- 2.0 g/6 h, respectively, P less than 0.01). Only small changes were observed in postprandial plasma levels of glucose and insulin after the fructose meal, but the plasma levels of lactate increased more with fructose than with the glucose meal. These results suggest that there might be some advantages (higher thermogenesis and carbohydrate oxidations) in using fructose as part of the carbohydrate source in diet of people with obesity and/or insulin resistance.

Interaction of lipid and carbohydrate metabolism after infusions of lipids or of lipid lowering agents: lack of a direct relationship between free fatty acid concentrations and glucose disposal.

The present work was planned to study the effects of changes in lipid metabolism irrespective of FFA concentrations (FFA) on the regulation of oxidative and nonoxidative disposal of a glucose infusion during hyperinsulinaemia. Fifteen normal volunteers participated in the 3 protocols, in which 1) Intralipid 2) beta-pyridylcarbinol or 3) isotonic saline were infused during 2 hours. Thereafter, these infusions were discontinued and a two-hour euglycaemic hyperinsulinaemic clamp was performed. All three studies were carried out in combination with indirect calorimetry to measure glucose uptake, and oxidative and nonoxidative glucose disposal (corresponding essentially to glucose storage). Plasma FFA concentrations were 508 +/- 34, 601 +/- 43 and 546 +/- 45 mumol/l in the basal state during the Intralipid, beta-pyridylcarbinol and control protocols. It increased to 960 +/- 71 mumol/l after the Intralipid infusion, fell to 246 +/- 17 mumol/l after the beta-pyridylcarbinol infusion, vs 600 +/- 48 mumol/l in the control. At the end of the glucose-insulin clamp the values were low in the 3 protocols: 263 +/- 17, 233 +/- 19 and 204 +/- 14 mumol/l. Intralipid infusion prior to the clamp protocol induced a suppression of both insulin-mediated glucose uptake (4.91 +/- 0.46 (Intralipid) vs 6.83 +/- 0.63 mg.kg-1.min-1 (saline)) and storage (1.61 +/- 0.34 vs 2.99 +/- 0.53 mg.kg-1.min-1) while beta-pyridylcarbinol infusion induced an increased insulin-mediated glucose uptake (8.58 +/- 0.37 mg.kg-1.min-1) and in glucose storage (4.29 +/- 0.31 mg.kg-1.min-1) (p less than 0.5 vs Intralipid). These changes occurred even though FFA plasma concentrations were similar in the 3 experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Resistance to insulin mediated glucose disposal in obese subjects: respective effect of lipid metabolism and glycemia.

The present study was designed to assess the respective effect of altered lipid metabolism and hyperglycemia on glucose metabolism in vivo in obese subjects. Six young obese non-diabetic volunteers were studied on four occasions during hyperinsulinemic clamp, twice during euglycemia and twice during hyperglycemia, with or without the infusion of beta-pyridylcarbinol, an inhibitor of lipid metabolism. Glucose oxidation was calculated from continuous respiratory exchange measurements, and glucose storage was obtained as the difference between total glucose disposal and glucose oxidation. Two-way analysis of variance (with interaction term) demonstrated (i) a significant increase for total glucose disposal with beta-pyridylcarbinol but no significant effect of hyperglycemia and no interaction between the two treatments, and (ii) an important increase of beta-pyridylcarbinol to enhance glucose storage but no significant effect of hyperglycemia and no interaction between the two treatments. These results show that obese people, at physiological insulinemia, enhance their glucose disposal and glucose storage when lipid oxidation is artificially lowered. This suggests that enhanced lipid oxidation is related to insulin resistance in these patients. However, hyperglycemia in these patients failed to compensate for defective glucose disposal or storage.

Thermogenic effects of various beta-adrenoceptor agonists in humans: their potential usefulness in the treatment of obesity.

The thermogenic effect of various beta-agonists was studied in humans by using indirect calorimetry. Epinephrine was found to be markedly thermogenic: at infusion rates of 0.01, 0.03, and 0.1 microgram.min-1.kg fat-free mass-1 resting energy expenditure (REE) increased by 8%, 16%, and 29%, respectively; in addition, a dose-dependent increase in heart rate was observed. Dopamine at high infusion rates also induces beta-agonist effects: at 5 and 10 micrograms.min-1.kg-1, REE increased by 6% and 15%, respectively, an effect that could be mediated by the release of endogenous norepinephrine. The phenethanolamine derivative Ro 16-8714 given per os at a single dose of 5 and 20 mg led to an increase of REE of 10% and 21%, whereas heart rate was enhanced by 8% and 49%, respectively. The new beta-adrenoreceptor agonist Ro 40-2148, given per os to six normal-weight young subjects at a single dose of 200 or 400 mg, induced no significant change in REE, whereas after 800 mg, REE was increased in all subjects (+3 to +17%, mean + 8%) without inducing tachycardia.

Energy and substrate metabolism in obesity and postobese state.

The total energy expenditure (EE) of human beings is represented by basal metabolic rate (which corresponds to 60-70% of EE), dietary-induced thermogenesis (10% of EE), and the energy expended in physical activity (20-30% of EE). Obese individuals have an increased total EE compared with lean subjects; this increase is essentially due to an increased lean body mass concomitant with obesity, and is completely reverted after weight loss. Glucose-induced thermogenesis (GIT), measured during an oral glucose tolerance test (OGTT) or hyperinsulinemic-euglycemic clamps, has been found to be decreased in obese individuals, although some discrepancy exists between studies. The observed decreases in GIT show a gradation, increasing progressively from obese patients with normal glucose tolerance to obese patients with impaired glucose tolerance (IGT) to obese patients with non-insulin-dependent diabetes mellitus (NIDDM) and an increased insulin response after OGTT to obese patients with NIDDM and a hypoinsulinemic response after OGTT. The defect in GIT appears to be related to impairment in nonoxidative glucose storage and with the degree of insulin resistance. Obese patients after weight loss show a further decrease in GIT after OGTT or during a euglycemic clamp, which remains unclear. Obese patients have an increased basal lipid oxidation and a decreased suppression of lipid oxidation after OGTT or during a euglycemic clamp. Glucose oxidation and storage are both markedly decreased during a euglycemic clamp. In contrast, the defect in glucose storage is less apparent after OGTT, due to the compensatory effect of hyperglycemia and hyperinsulinemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Evolution of glucose induced thermogenesis in obese subjects with and without diabetes: a six-year follow-up study.

The thermogenic response to a 100 g oral glucose load was measured prospectively (by indirect calorimetry) in three groups of obese subjects: (1) normal glucose tolerance (n = 12, initial weight 86.4 +/- 3.9 kg, BMI 30.4 +/- 1.1 kg/m2; (2) impaired glucose tolerance (n = 8, initial weight 105.3 +/- 7.6 kg, body mass index (BMI) 37.6 +/- 2.9 kg/m2; (3) diabetes (n = 12), initial weight 102.1 +/- 5.3 kg, BMI 36.2 +/- 2.0 kg/m2). The thermogenic response to glucose averaged 6.8 +/- 1.1 and 7.0 +/- 1.0 per cent, in the two non-diabetic obese groups respectively, and was significantly lower in the obese diabetic group (3.1 +/- 0.8 per cent). With the evolution of obesity (i.e. 6 years later), the glucose-induced thermogenesis (GIT) was significantly reduced in the non-diabetic groups (P less than 0.05) to 4.1 +/- 0.8 and 3.0 +/- 1.1 per cent respectively, and was still blunted in the diabetic group (2.1 +/- 0.7 per cent). The decrease in GIT was accompanied by a reduction in glucose tolerance and insulin response with no change in fasting plasma insulin. These effects were observed despite the fact that the body weight of the subject did not change significantly over the 6-year period. It is concluded that the decrease in GIT which accompanies the worsening of glucose tolerance and the occurrence of diabetes is a mechanism which may contribute to maintain the obesity state by a reduction of energy expenditure.

Effect of trestatin, an amylase inhibitor, incorporated into bread, on glycemic responses in normal and diabetic patients.

The effect of incorporating the pancreatic alpha-amylase inhibitor trestatin into bread on postprandial plasma glucose and insulin excursions was tested in healthy volunteers and non-insulin-dependent diabetic patients. At both dose levels of trestatin (3 and 6 mg/75 g starch) the peak values of plasma glucose and insulin were reduced markedly (compared with placebo) after the ingestion of 75 g starch in the form of bread. In healthy control subjects as well as in diabetic patients, trestatin produced significantly lower insulin excretions but also significant reductions in incremental plasma glucose areas in a dose-dependent fashion. It is concluded that it is technologically feasible to incorporate trestatin into starchy foods without loss of activity or impairment of taste. Furthermore, the positive effect of trestatin on glycemic and insulinemic responses in diabetics and the lack of serious side effects offer a great potential in the dietary treatment of diabetic patients.

Cholesterol-lowering effect of skim milk from immunized cows in hypercholesterolemic patients.

The effect of skim milk from cows immunized against a variety of human intestinal bacteria on serum cholesterol concentrations was examined in 11 patients with primary hypercholesterolemia in a 24-wk, randomized, double-blind, placebo-controlled, crossover study. After a 4-wk baseline period, patients were treated for 8 wk either with skim milk from immunized cows (active) or with control skim milk (placebo) followed by an 8-wk period with the treatment order reversed. Eight weeks of active treatment with skim milk from immunized cows reduced serum total cholesterol concentrations by 0.52 +/- 0.59 mmol/L (mean +/- SD; P less than 0.025), or 8%, LDL cholesterol by 0.16 +/- 0.59 mmol/L (NS), or 4%, and the atherogenic index (total cholesterol/HDL cholesterol) by 0.42 +/- 1.85 (P less than 0.05), or 8%, compared with the placebo treatment. Reversal of the favorable development occurred upon cessation of active treatment. We conclude that daily supplementation of a normal diet with skim milk from immunized cows can result in a significant reduction of elevated blood cholesterol concentrations.