Replacement Of Saturated Fatty Acids Research Articles

A High-Fat Diet Rich In Polyunsaturated Fatty Acids Downregulates Glut4, But Not Skeletal Muscle Glycogen.

High fat diets (HFD) are linked to the development of obesity and type 2 diabetes (T2D), characterized by defects in glycogen storage and increased lipid accumulation in skeletal muscle. Replacement of saturated fatty acids in high fat diets, with unsaturated (mono- and poly-unsaturated) fatty acids has been shown to reduce risks for insulin resistance, obesity and T2D. PURPOSE: The purpose of this study was to determine the effects of HFD differing in fatty acid composition, on skeletal muscle glycogen, mitochondrial, GLUT4, and lipid contents. METHODS: Male Sprague Dawley rats were fed a Western-style (21% fat by weight; 41% total energy) HFD for 9 weeks to induce obesity and then were divided into one of three HFD groups for an additional 6 weeks; a control chow group followed a 15-week low fat diet. Animals consumed either a) low fat Chow diet (CD) (4.8 % fat; 0.74% saturated; 2% mono; 1.77% poly; n=6), b) mixed fat Western diet (WD) (21% fat; 9.76% saturated; 7.68% mono; 3.48% poly; n=6), c) HFD rich in monounsaturated fatty acids (MUFA) (21% fat; 2.82% saturated; 16.01% mono; 2.18% poly; n=6), d) HFD rich in polyunsaturated fatty acids (PUFA) (21% fat; 2% fat; 2.97% mono; 16% poly; n=7). After 15 weeks, glycogen (periodic acid-schiff staining) mitochondria, GLUT4, and lipid content were measured in extensor digitorum longus muscle using immunohistochemical staining techniques and quantified with imageJ software. RESULTS: Following the 6-week treatment period, body weight (g) in the WD group was significantly greater compared to MUFA (p=0.0006), PUFA (p=0.02), and CD (p<0.0001). Glycogen content was significantly greater (p=0.04) in animals fed a WD compared to CD. (AU±SEM; CD: 4.41±0.04; WD: 4.74±0.13; MUFA: 4.54±0.08; PUFA: 4.54±0.11; one-way ANOVA p=0.11). A HFD rich in PUFA resulted in impaired GLUT4 content (p=0.02) compared to a CD (AU±SEM; CD: 77.38±2.22; WD: 63.46±3.80; MUFA: 61.49±8.46; PUFA: 52.84±5.13; one-way ANOVA p=0.03). There were no significant effects on mitochondrial or lipid content. CONCLUSION: A high fat diet rich in polyunsaturated fatty acids results in significantly lower GLUT4 content without negatively impacting skeletal muscle glycogen storage in high fat diet induced obese rats. A high fat diet rich in saturated fat resulted in greater muscle glycogen content compared to low fat fed rats.

Abstract MP068: Dietary Fatty Acids and Coronary Heart Disease in Mortality in the Alpha Omega Cohort

Background: Replacement of saturated fatty acids (SFA) with polyunsaturated fatty acids (PUFA) is associated with a lower risk of coronary heart disease (CHD) in the general population. Whether this is also the case for CHD patients is not yet clear. In this observational study of Dutch CHD patients, we examined the risk of CHD mortality for the exchange of SFA with total unsaturated fatty acids (UFA), PUFA and cis -monounsaturated fatty acids (MUFA). Methods: We included 4146 post-myocardial infarction patients aged 60-80 (78% male; Alpha Omega Cohort) in whom diet was assessed at baseline (2002-2006) by a validated 203-item food-frequency questionnaire. Cause-specific mortality was monitored until January 2013. Iso-caloric replacement of SFA with (subgroups of) UFA in relation to CHD mortality was studied in quintiles and continuously per 5 energy percent (en%), using Cox regression models. Hazard ratios (HR, 95%-CI) were obtained after adjustment for age, sex, BMI, smoking, education, physical activity, cardiovascular drugs (anticoagulants, antihypertensives, statins), diabetes, and dietary factors, i.e. total energy, protein (en%), carbohydrates (en%), trans fatty acids (en%), dietary fiber (g/d) and dietary cholesterol (mg/d). The model for PUFA also included MUFA as a covariate, and vice versa . Results: During a median follow-up of 7.3 years, there were 888 deaths including 249 CHD deaths. SFA replacement was inversely associated with CHD mortality when comparing extreme quintiles of intake, which was statistically significant for total UFA (HR: 0.44; 95% CI: 0.21-0.92; P = 0.03) and non-significant for PUFA (0.58, 0.31-1.09) and MUFA (0.81, 0.45-1.49). When expressed per 5 en% (Figure), replacing SFA with either UFA, PUFA or MUFA was associated with a more than 30% lower risk of CHD mortality. Findings were similar when confined to statin users. Conclusion: In well-treated CHD patients, replacement of SFA by UFA is associated with a lower CHD mortality risk.

Dietary fatty acid intake after myocardial infarction: a theoretical substitution analysis of the Alpha Omega Cohort

Replacement of saturated fatty acids (SFAs) with unsaturated fatty acids (UFAs), especially polyunsaturated fatty acids (PUFAs), has been associated with a lower risk of ischemic heart disease (IHD). Whether this replacement is beneficial for drug-treated patients with cardiac disease is not yet clear. In a prospective study of Dutch patients with cardiac disease (Alpha Omega Cohort), we examined the risk of cardiovascular disease (CVD) and IHD mortality when the sum of SFAs and trans fatty acids (TFAs) was theoretically replaced by total UFAs, PUFAs, or cis monounsaturated fatty acids (MUFAs). We included 4146 state-of-the-art drug-treated patients aged 60-80 y with a history of myocardial infarction (79% male patients) and reliable dietary data at baseline (2002-2006). Cause-specific mortality was monitored until 1 January 2013. HRs for CVD mortality and IHD mortality for theoretical, isocaloric replacement of dietary fatty acids (FAs) in quintiles (1-5) and continuously (per 5% of energy) were obtained from Cox regression models, adjusting for demographic factors, medication use, and lifestyle and dietary factors. Patients consumed, on average, 17.5% of energy of total UFAs, 13.0% of energy of SFAs, and <1% of energy of TFAs. During ∼7 y of follow-up, 372 CVD deaths and 249 IHD deaths occurred. Substitution modeling yielded significantly lower risks of CVD mortality when replacing SFAs plus TFAs with total UFAs [HR in quintile 5 compared with quintile 1: 0.45 (95% CI: 0.28, 0.72)] or PUFAs [HR: 0.66 (95% CI: 0.44, 0.98)], whereas HRs in cis MUFA quintiles were nonsignificant. HRs were similar for IHD mortality. In continuous analyses, replacement of SFAs plus TFAs with total UFAs, PUFAs, or cis MUFAs (per 5% of energy) was associated with significantly lower risks of CVD mortality (HRs between 0.68 and 0.75) and IHD mortality (HRs between 0.55 and 0.70). Shifting the FA composition of the diet toward a higher proportion of UFAs may lower CVD mortality risk in drug-treated patients with cardiac disease. This study was registered at clinicaltrials.gov as NCT03192410.

Progressing Insights into the Role of Dietary Fats in the Prevention of Cardiovascular Disease.

Dietary fats have important effects on the risk of cardiovascular disease (CVD). Abundant evidence shows that partial replacement of saturated fatty acids (SAFA) with unsaturated fatty acids improves the blood lipid and lipoprotein profile and reduces the risk of coronary heart disease (CHD). Low-fat diets high in refined carbohydrates and sugar are not effective. Very long-chain polyunsaturated n-3 or omega-3 fatty acids (n-3 VLCPUFA) present in fish have multiple beneficial metabolic effects, and regular intake of fatty fish is associated with lower risks of fatal CHD and stroke. Food-based guidelines on dietary fats recommend limiting the consumption of animal fats high in SAFA, using vegetable oils high in monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA), and eating fatty fish. These recommendations are part of a healthy eating pattern that also includes ample intake of plant-based foods rich in fiber and limited sugar and salt.

Adverse effects on insulin secretion of replacing saturated fat with refined carbohydrate but not with monounsaturated fat: A randomized controlled trial in centrally obese subjects

Current dietary guidelines recommend the replacement of saturated fatty acids (SAFAs) with carbohydrates or monounsaturated fatty acids (MUFAs) based on evidence on lipid profile alone, the chronic effects of the mentioned replacements on insulin secretion and insulin sensitivity are however unclear. To assess the chronic effects of the substitution of refined carbohydrate or MUFA for SAFA on insulin secretion and insulin sensitivity in centrally obese subjects. Using a crossover design, randomized controlled trial in abdominally overweight men and women, we compared the effects of substitution of 7% energy as carbohydrate or MUFA for SAFA for a period of 6weeks each. Fasting and postprandial blood samples in response to corresponding SAFA, carbohydrate, or MUFA-enriched meal-challenges were collected after 6weeks on each diet treatment for the assessment of outcomes. As expected, postprandial nonesterified fatty acid suppression and elevation of C-peptide, insulin and glucose secretion were the greatest with high-carbohydrate (CARB) meal. Interestingly, CARB meal attenuated postprandial insulin secretion corrected for glucose response; however, the insulin sensitivity and disposition index were not affected. SAFA and MUFA had similar effects on all markers except for fasting glucose-dependent insulinotropic peptide concentrations, which increased after MUFA but not SAFA when compared with CARB. In conclusion, a 6-week lower-fat/higher-carbohydrate (increased by 7% refined carbohydrate) diet may have greater adverse effect on insulin secretion corrected for glucose compared with isocaloric higher-fat diets. In contrast, exchanging MUFA for SAFA at 7% energy had no appreciable adverse impact on insulin secretion.

Saturated Fats Versus Polyunsaturated Fats Versus Carbohydrates for Cardiovascular Disease Prevention and Treatment.

The effects of saturated fatty acids (SFAs) on cardiovascular disease (CVD) risk are modulated by the nutrients that replace them and their food matrices. Replacement of SFAs with polyunsaturated fatty acids has been associated with reduced CVD risk, although there is heterogeneity in both fatty acid categories. In contrast, replacement of SFAs with carbohydrates, particularly sugar, has been associated with no improvement or even a worsening of CVD risk, at least in part through effects on atherogenic dyslipidemia, a cluster of traits including small, dense low-density lipoprotein particles. The effects of dietary SFAs on insulin sensitivity, inflammation, vascular function, and thrombosis are less clear. There is growing evidence that SFAs in the context of dairy foods, particularly fermented dairy products, have neutral or inverse associations with CVD. Overall dietary patterns emphasizing vegetables, fish, nuts, and whole versus processed grains form the basis of heart-healthy eating and should supersede a focus on macronutrient composition.

Emerging Nutrition Science on Fatty Acids and Cardiovascular Disease: Nutritionists' Perspectives

AbstractRecent dietary guidance for heart health recommends a reduction (by ∼50%) in saturated fatty acid (SFA) intake to reduce LDL cholesterol and to decrease risk of cardiovascular disease (CVD). The 2010 Dietary Guidelines for Americans recommends substituting unsaturated fat [both polyunsaturated and monounsaturated fatty acids (PUFAs and MUFAs, respectively)] for SFAs. There are many dietary options that can be implemented to replace SFAs, given the different sources of unsaturated fats in the food supply. Compelling evidence exists for the cardioprotective benefits of n–3 (ω-3) PUFAs, both marine- and plant-derived. In addition, the evidence of cardioprotective benefits of n–6 (ω-6) PUFAs is strong, whereas that for MUFAs is mixed, although there is emerging evidence of benefits. Quantitatively, lowering SFAs by 50% will require, in part, substituting food sources of n–6 and n–3 PUFAs and MUFAs for food sources of SFAs. The use of n–3 PUFAs as a replacement for SFAs will result in a shortfall in reaching the SFA goal because of the relatively low amounts that can be incorporated in the diet, even with very high n–3 PUFA substitution. SFAs also can be replaced with dietary carbohydrate and/or protein. Replacing SFAs with carbohydrate, specifically refined sources, however, has little impact on reducing CVD risk. There is evidence about the health benefits of dietary protein on CVD risk, which merits study. Dietary guidelines have advanced considerably with the “replacement of SFA with unsaturated fat message” instead of recommending decreasing SFAs alone. A key question that remains is what is the optimal mix of macronutrients to maximally reduce CVD risk.

Development of a Food-Exchange Model to Replace Saturated Fat wth MUFAs and n–6 PUFAs in Adults at Moderate Cardiovascular Risk

The recommendation to reduce saturated fatty acid (SFA) consumption to ≤10% of total energy (%TE) is a key public health target aimed at lowering cardiovascular disease (CVD) risk. Replacement of SFA with unsaturated fats may provide greater benefit than replacement with carbohydrates, yet the optimal type of fat is unclear. The aim of the DIVAS (Dietary Intervention and Vascular Function) study was to develop a flexible food-exchange model to investigate the effects of substituting SFAs with monounsaturated fatty acids (MUFAs) or n–6 (ω-6) polyunsaturated fatty acids (PUFAs) on CVD risk factors. In this parallel study, UK adults aged 21–60 y with moderate CVD risk (50% greater than the population mean) were identified using a risk assessment tool (n = 195; 56% females). Three 16-wk isoenergetic diets of specific fatty acid (FA) composition (%TE SFA:%TE MUFA:%TE n–6 PUFA) were designed using spreads, oils, dairy products, and snacks as follows: 1) SFA-rich diet (17:11:4; n = 65); 2) MUFA-rich diet (9:19:4; n = 64); and 3) n–6 PUFA-rich diet (9:13:10; n = 66). Each diet provided 36%TE total fat. Dietary targets were broadly met for all intervention groups, reaching 17.6 ± 0.4%TE SFA, 18.5 ± 0.3%TE MUFA, and 10.4 ± 0.3%TE n–6 PUFA in the respective diets, with significant overall diet effects for the changes in SFAs, MUFAs, and n–6 PUFAs between groups (P < 0.001). There were no differences in the changes of total fat, protein, carbohydrate, and alcohol intake or anthropometric measures between groups. Plasma phospholipid FA composition showed changes from baseline in the proportions of total SFAs, MUFAs, and n–6 PUFAs for each diet group, with the changes in SFAs and MUFAs differing between the groups (P < 0.001). In conclusion, successful implementation of the food-exchange model broadly achieved the dietary target intakes for the exchange of SFAs with MUFAs or n–6 PUFAs with minimal disruption to the overall diet in a free-living population. This trial was registered at clinicaltrials.gov>as NCT01478958.

Dietary fatty acids in the secondary prevention of coronary heart disease: a systematic review, meta-analysis and meta-regression

ObjectivePrevious systematic reviews were not restricted to either primary or secondary prevention trials, this study aimed to investigate the effects of reduced and/or modified fat diets and dietary fatty acids...

SFAs do not impair endothelial function and arterial stiffness

Background: It is uncertain whether saturated fatty acids (SFAs) impair endothelial function and contribute to arterial stiffening.Objective: We tested the effects of replacing SFAs with monounsaturated fatty acids (MUFAs) or carbohydrates on endothelial function and arterial stiffness.Design: With the use of a parallel-designed randomized controlled trial in 121 insulin-resistant men and women, we measured vascular function after 1 mo of consumption of a high-SFA (HS) diet and after 24 wk after random assignment to the HS diet or diets that contained <10% SFAs and were high in either MUFAs or carbohydrates. The primary outcome was a change in flow-mediated dilation (FMD), and secondary outcomes were changes in carotid to femoral pulse wave velocity (PWV) and plasma 8-isoprostane F2α-III concentrations.Results: For 112 participants with data available for analysis on the specified outcomes, no significant differences were shown. FMD with the HS reference diet was 6.7 ± 2.2%, and changes (95% CIs) after 6 mo of intervention were +0.3 (−0.4, 1.1), −0.2 (−0.8, 0.5), and −0.1 (−0.6, 0.7) with HS, high-MUFA (HM), and high-carbohydrate (HC) diets, respectively. After consumption of the HS reference diet, the geometric mean (±SD) PWV was 7.67 ± 1.62 m/s, and mean percentages of changes (95% CIs) were −1.0 (−6.2, 4.3) with the HS diet, 2.7 (−1.4, 6.9) with the HM diet, and −1.0 (−5.5, 3.4) with the HC diet. With the HS reference diet, the geometric mean (±SD) plasma 8-isoprostane F2α-III concentration was 176 ± 85 pmol/L, and mean percentage of changes (95% CIs) were 1 (−12, 14) with the HS diet, 6 (−5, 16) with the HM diet, and 4 (−7, 16) with the HC diet.Conclusion: The replacement of SFAs with MUFAs or carbohydrates in healthy subjects does not affect vascular function. This trial was registered at Current Controlled Trials (http://www.controlled-trials.com/ISRCTN) as ISRCTN 29111298.

Application of the BRAFO tiered approach for benefit–risk assessment to case studies on dietary interventions

The respective examples, described in this paper, illustrate how the BRAFO-tiered approach, on benefit–risk assessment, can be tested on a wide range of case studies. Various results were provided, ranging from a quick stop as the result of non-genuine benefit–risk questions to continuation through the tiers into deterministic/probabilistic calculations. The paper illustrates the assessment of benefits and risks associated with dietary interventions. The BRAFO tiered approach is tested with five case studies. In each instance, the benefit–risk approach is tested on the basis of existing evaluations for the individual effects done by others; no new risk or benefit evaluations were made. The following case studies were thoroughly analysed: an example of food fortification, folic acid fortification of flour, macronutrient replacement/food substitution; the isocaloric replacement of saturated fatty acids with carbohydrates; the replacement of saturated fatty acids with monounsaturated fatty acids; the replacement of sugar-sweetened beverages containing mono- and disaccharides with low calorie sweeteners and an example of addition of specific ingredients to food: chlorination of drinking water.

Effect of changing the amount and type of fat and carbohydrate on insulin sensitivity and cardiovascular risk: the RISCK (Reading, Imperial, Surrey, Cambridge, and Kings) trial

Background: Insulin sensitivity (Si) is improved by weight loss and exercise, but the effects of the replacement of saturated fatty acids (SFAs) with monounsaturated fatty acids (MUFAs) or carbohydrates of high glycemic index (HGI) or low glycemic index (LGI) are uncertain.Objective: We conducted a dietary intervention trial to study these effects in participants at risk of developing metabolic syndrome.Design: We conducted a 5-center, parallel design, randomized controlled trial [RISCK (Reading, Imperial, Surrey, Cambridge, and Kings)]. The primary and secondary outcomes were changes in Si (measured by using an intravenous glucose tolerance test) and cardiovascular risk factors. Measurements were made after 4 wk of a high-SFA and HGI (HS/HGI) diet and after a 24-wk intervention with HS/HGI (reference), high-MUFA and HGI (HM/HGI), HM and LGI (HM/LGI), low-fat and HGI (LF/HGI), and LF and LGI (LF/LGI) diets.Results: We analyzed data for 548 of 720 participants who were randomly assigned to treatment. The median Si was 2.7 × 10−4 mL · μU−1 · min−1 (interquartile range: 2.0, 4.2 × 10−4 mL · μU−1 · min−1), and unadjusted mean percentage changes (95% CIs) after 24 wk treatment (P = 0.13) were as follows: for the HS/HGI group, −4% (−12.7%, 5.3%); for the HM/HGI group, 2.1% (−5.8%, 10.7%); for the HM/LGI group, −3.5% (−10.6%, 4.3%); for the LF/HGI group, −8.6% (−15.4%, −1.1%); and for the LF/LGI group, 9.9% (2.4%, 18.0%). Total cholesterol (TC), LDL cholesterol, and apolipoprotein B concentrations decreased with SFA reduction. Decreases in TC and LDL-cholesterol concentrations were greater with LGI. Fat reduction lowered HDL cholesterol and apolipoprotein A1 and B concentrations.Conclusions: This study did not support the hypothesis that isoenergetic replacement of SFAs with MUFAs or carbohydrates has a favorable effect on Si. Lowering GI enhanced reductions in TC and LDL-cholesterol concentrations in subjects, with tentative evidence of improvements in Si in the LF-treatment group. This trial was registered at clinicaltrials.gov as ISRCTN29111298.

UK Food Standards Agencycis-monounsaturated fatty acid workshop report

The UK Food Standards Agency convened a group of expert scientists to review current research investigating the optimal dietary intake forn-9cis-monounsaturated fatty acids (MUFA). The aim was to review the mechanisms underlying the reported beneficial effects of MUFA on CHD risk, and to establish priorities for future research. The issue of optimal MUFA intake is contingent upon optimal total fat intake; however, there is no consensus of opinion on what the optimal total fat intake should be. Thus, it was recommended that a large multi-centre study should look at the effects on CHD risk of MUFA replacement of saturated fatty acids in relation to varying total fat intakes; this study should be of sufficient size to take account of genetic variation, sex, physical activity and stage of life factors, as well as being of sufficient duration to account for adaptation to diets. Recommendations for studies investigating the mechanistic effects of MUFA were also made. Methods of manipulating the food chain to increase MUFA at the expense of saturated fatty acids were also discussed.

Olive oil and the Mediterranean diet.

The high intake of olive oil in the Mediterranean diet contributes to the low intake of saturated fatty acids among populations in Southern Europe and is associated with a low incidence of coronary heart disease. Replacement of saturated fatty acids with oleic acid leads to a reduction in low-density lipoprotein (LDL) cholesterol without decreasing the concentration of high density lipoprotein (HDL) cholesterol. Oleic acid, however, may not be neutral with regards to its effects on risk of thrombosis which may have adverse consequences in populations with established atherosclerosis.

Fish for a healthy heart

Today it is generally accepted that diet has to be implemented into the strategies for primary and secondary prevention of cardiovascular disease, in particular coronary artery disease. Possible cardioprotective mechanisms of a prudent nutrition include beneficial effects on lipid profile, oxidative stress, thromboembolic events and suppression of arrhythmias as well as sudden death. Common to all diets recommended by professional organisations, like the American Heart Association or the European Society of Cardiology, the replacement of saturated fatty acids and trans fatty acids with polyunsaturated fatty acids is regarded as a key feature.

Partial replacement of saturated fatty acids with almonds or walnuts lowers total plasma cholesterol and low-density-lipoprotein cholesterol

Sixteen normolipidemic male volunteers aged 41 +/- 9 y (mean +/- SD) consumed a diet providing 36% of energy as fat (92 g fat/d) for 9 wk. A daily supplement of nuts (providing half of the total fat intake) was provided against a common background diet. In the first 3-wk period the background diet was supplemented with raw peanuts (50 g/d), coconut cubes (40 g/d), and a coconut confectionary bar (50 g/d), designed to provide 47 g fat with a ratio of polyunsaturated to monounsaturated to saturated fatty acids (P:M:S) to match the Australian diet (reference diet). During the following 3 wk the background diet was supplemented with monounsaturated fatty acid-rich raw almonds (84 g/d), equivalent to 46 g fat, and during the final 3-wk period the background diet was supplemented with polyunsaturated fatty acid-rich walnuts (68 g/d), equivalent to 46 g fat. Compared with the reference diet there were significant reductions in total and LDL cholesterol, 7% and 10%, respectively, after supplementation with almonds, and 5% and 9%, respectively, after supplementation with walnuts.

The Role of Dietary Olive Oil from the Islamic and Scientific Perspectives

DOI: http://dx.doi.org/10.5915/22-2-13551 Health authorities have advised Americans to modify their diet in order to reduce the risk of heart disease and cancer. The dietary goals for the U.S. suggest reducing average dietary fat to 30% of total energy, reducing cholesterol to 300 mg per day, and replacement of saturated fatty acids by polyunsaturated or monounsaturated fatty acids. Monounsaturated fats have been the object of considerable nutritional interest, as epidemiological studies hove determined that people in Mediterranean countries, where the predominant oil consumed is olive oil (a highly monounsaturated oil), suffer a very low incidence of cardiovascular disease. A methodology is urgently needed for assessment of adherence to fat-controlled diets in free-living subjects, both long term and daily or even from meal to meal. In this respect, the Holy Qur'iin and the Sunnah of the Prophet Muhammad (PBUH) offer great promise. The aim of this undertaking is to present o survey of literature on the role of dietary olive oil from an Islamic perspective.

Are there atherogenic dietary proteins?

Studies with rabbits have shown that the nature of protein in the diet can influence the concentration of cholesterol in plasma and the severity of arterial lesions. The feeding of animal proteins such as beef protein, casein or fish protein results in a high degree of aortic atherosclerosis. On the other hand, when rabbits are fed on diets containing plant protein preparations such as wheat gluten, corn protein or soy protein, the severity of aortic lesions is minimal. The animal proteins produce higher concentrations of serum cholesterol than the plant proteins. The rise in serum cholesterol induced by the milk protein casein in comparison with soy protein is also found in guinea pigs, pigs, rats, hamsters, but not in domestic fowl, calves and mice. The ultimate aim of such nutrition research with experimental animals is to provide further insight into practical means of decreasing the concentration of plasma cholesterol in man through changes in dietary habits. A decrease in plasma cholesterol will decrease incidence of atherosclerotic disease as manifested, for example, by myocardial infarction. A number of investigators have reported that intake of soy protein in contrast to animal proteins by hypercholesterolaemic patients reduced plasma cholesterol by 0 to 30%. Such studies are often quoted to support the view that the replacement of animal proteins in the diet by vegetable proteins would lower plasma cholesterol in man. However, the intake of soy protein in the studies with hypercholesterolemic patients also involved other changes in the diet, including the elimination of dietary cholesterol and replacement of saturated fatty acids by polyunsaturated fatty acids. In studies in which the type of protein was the only dietary variable, only a small effect or no effect at all of mixed animal proteins or casein over soy protein on plasma cholesterol was seen in healthy subjects while a slightly larger effect was seen in hypercholesterolemic patients. Thus it is questionable whether changes in the nature of protein in man could really contribute to the prevention of atherosclerosis.