Dietary Fat Reduction Research Articles

Socio-Demographic Characteristics and Nutritional Status of Individuals by Stages of Change for Dietary Fat Reduction

Changes in lifestyle and food habits have been implicated in the increasing rate of nutrition related chronic diseases in Malaysia. A cross-sectional study was conducted to identify socio-demographic characteristic and nutritional status of individuals by their readiness to reduce dietary fat intake. A total of 202 non-academic staff aged 18-56 years at Universiti Putra Malaysia participated in the study. Information on demographic, socio-economic and stages of change related to dietary fat reduction were collected using a pre-tested interview-administered questionnaire. Subjects were measured for weight, height and waist circumference. Fasting blood through venipuncture was obtained for triglycerides, LDL-, HDL- and total cholesterol. Energy and dietary fat intake were estimated based on two days 24 h diet recall. Chi-square test and Analysis of Covariance (ANCOVA) were used for data analysis. Of the respondents, about 12% reported reduced fat intake, 20% were not committed to change and more than half (68%) were in preparation stage. There was no significant association between stages of change and socio-demographic factors. Body mass index was highest in preparation group (Mean±SE = 24.93±0.35 kg/m2) [F = 5.686; p<0.01]. Men in action/maintenance group (Mean±SE = 76.22±4.17 cm) had significantly lower adjusted mean waist circumference than those in preparation group (Mean±SE = 89.77±1.85 cm) [F = 5.324, p<0.01]. No significant difference across stages was observed in waist circumference for women, lipid profile, caloric and fat intake. It is important to identify characteristics of individuals by their readiness to change dietary behaviors so that effective nutrition strategies can be developed and implemented to meet their dietary needs and goals.

A New Health Promotion Model for Lone Workers: Results of the Safety &amp; Health Involvement For Truckers (SHIFT) Pilot Study

This study was designed to evaluate the effectiveness of a new health promotion model for lone workers. A single group pre- or posttest design was used to evaluate intervention effectiveness for reducing body weight and increasing healthful and safe behaviors. Truck drivers (n = 29) from four companies participated in a 6-month intervention involving a weight loss and safe driving competition, computer-based training, and motivational interviewing. Objectively measured body weight reduced by 7.8 lbs (DeltaSD = 11.5, Deltad = 0.68, P = 0.005), and survey measures showed significant reductions in dietary fat and sugar consumption. An objective measure of safe driving also showed significant improvement, and increases in exercise motivational stage and walking fitness approached significance. Results suggest that the new intervention model is substantially more engaging and effective with truck drivers than previous education-based tactics.

Central nervous system and muscle involvement in an adolescent patient with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency

We report an adolescent case of late-onset riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (MADD) characterized by intermittent nausea and depressive state as early symptoms. At the age of 12 years and 11 months, the patient experienced intermittent nausea and vomiting, and depressive state. She was on medication for depression for 5 months but it was ineffective. Brain magnetic resonance imaging showed disseminated high-intensity areas in the periventricular white matter and in the splenium of the corpus callosum on T2-weighted images and fluid-attenuated inversion-recovery images. Progressive muscle weakness occurred and blood creatine kinase level was found to be elevated. The muscle biopsy revealed lipid storage myopathy. Urine organic acid analysis and mutation analysis of the ETFDH gene confirmed the diagnosis of MADD. With oral supplements of riboflavin and l-carnitine, in addition to a high-calorie and reduced-fat diet, her clinical symptoms improved dramatically. Early diagnosis is important because riboflavin treatment has been effective in a significant number of patients with MADD.

Association of CYP7A1 -278A&gt;C polymorphism and the response of plasma triglyceride after dietary intervention in dyslipidemic patients

We investigated the effect of the -278A>C polymorphism in the CYP7A1 gene on the response of plasma lipids to a reduced-fat diet for 6 to 8 weeks in a group of 82 dyslipidemic males with a mean age of 46.0 +/- 11.7 years. Individuals who presented at least one high alteration in total cholesterol, low-density lipoprotein cholesterol or triglyceride values were considered to be dyslipidemic. Exclusion criteria were secondary dyslipidemia due to diabetes mellitus, renal, liver, or thyroid disease. None of the subjects were using lipid-lowering medication. Baseline and follow-up lipid concentrations were measured. The genotypes were determined by the digestion of PCR products with the BsaI restriction endonuclease. There were statistically significant reductions in plasma total cholesterol, low-density lipoprotein cholesterol and triglyceride concentrations after dietary intervention. The minor allele C has a frequency of 43%. Carriers of the C allele had significantly lower triglyceride concentrations (P = 0.02) than AA homozygotes. After adjustment of covariates, subjects with the AC and CC genotypes showed a greater reduction in triglyceride concentrations compared to subjects with the AA genotype. Multiple linear regression analyses showed that the AC and CC CYP7A1 genotypes accounted for 5.2 and 6.2% of triglyceride concentration during follow-up and adjusted percent of change of triglyceride concentration, respectively. The present study provides evidence that -278A>C polymorphism in the CYP7A1 gene can modify triglyceride concentrations in response to a reduced fat diet in a dyslipidemic male population. This gene represents a potential locus for a nutrigenetic directed approach.

Dietary Fat Reduction Behaviors among African American, American Indian, and White Older Adults with Diabetes

Dietary self-management of diabetes is often difficult for older adults to practice, particularly in rural communities. We describe patterns and correlates of dietary fat reduction among older rural adults with diabetes of any type. In-home interviews were conducted with a multiethnic random sample of 701 adults 65 years and older with diabetes from two North Carolina counties. The Fat and Fiber Behavior Questionnaire was used to measure dietary behaviors. Separate multiple linear regressions assessed effects of gender, ethnicity, and diabetes education. In general, scores were more favorable for practices that involved modifying food preparation (e.g., avoiding frying) and less favorable for practices that involved changing foods consumed (e.g., substituting fruits and vegetables as desserts or snacks). American Indians and African Americans had less favorable scores than whites, and diabetes education was associated with greater fat restriction for women than men. Older men and ethnic minorities with diabetes should be targeted for dietary change education.

Current dietetic practices of obesity management in Saudi Arabia and comparison with Australian practices and best practice criteria

AbstractAim: To describe the dietetic practices of the treatment of obesity in Saudi Arabia and compare this with best practice criteria and the practice in Australia.Methods: Anonymous questionnaires were completed by dietitians in Saudi Arabia. The topics included barriers to obesity management, demand and level of service and strategies and approaches used for weight management. Best practice scores were based on those used to assess Australian dietitians.Results: A total of 253 dietitians participated in the survey. Of these, 175 (69%) were involved in the management of obesity. The best practice score for Australian dietitians was slightly greater than the scores of Saudi dietitians (median 43 vs 39). There was also a significant correlation between the best practice score and years of experience (r = 0.26, P &lt; 0.001). The most common assessment approaches were assessment of body mass index (87%) and exercise habits (81%), while the most common strategies for obesity management were: dietary total fat reduction (92%) and increase incidental daily activity (92%). The major barrier for establishment of a weight management clinic reported by 49% of participants was inadequate resources.Conclusion: Saudi Arabian dietetic practice for the management of obesity does incorporate most best practice recommendations, but some specific elements are rarely used.

Dietary fat consumption and health.

Dietary Guidelines have emerged over the past 30 years recommending that Americans limit their consumption of total fat and saturated fat as one way to reduce the risk of a range of chronic diseases. However, a low-fat diet is not a no-fat diet. Dietary fat clearly serves a number of essential functions. For example, maternal energy deficiency, possible exacerbated by very low-fat intakes (< 15% of energy), is one key determinant in the etiology of low birth weight. The debate continues over recommendations for limiting total fat and saturated fatty acid intake in children. Recent evidence indicates that diets with adequate energy providing less than 30% of energy from fat are sufficient to promote normal growth and normal sexual maturation. More attention needs to be devoted to the effect of dietary fat reduction on the nutrient density of children's diets. The association between dietary fat and CHD has been extensively studied. Diets high in saturated fatty acids and trans fatty acids increase LDL cholesterol levels, and in turn, the risk of heart disease. The relationship between high-carbohydrate/low-fat diets and CHD is more ambiguous because high-carbohydrate diets induce dyslipidemia in certain individuals. Obesity among adults and children is now of epidemic proportions in the United States. High-fat diets leading to excessive energy intakes are strongly linked to the increasing obesity in the United States. However, the prevalence of obesity has increased during the same time period that dietary fat intake (both in absolute terms and as a percentage of total dietary energy) has decreased. These trends suggest that a concomitant decrease in total dietary energy and modifications of other lifestyle factors, such as physical activity, also need to be emphasized. Obesity is also an independent risk factor for the development of diabetes. The current availability of fat-modified foods offers the potential for dietary fat reduction and treatment of the comorbidities associated with diabetes. However, to date, few studies have documented the effectiveness of fat-modified foods as part of a weight loss regimen or in reduction in CHD risks among individuals with diabetes mellitus. The association between total dietary fat and cancer is still under debate. While there is some evidence demonstrating associations between dietary fat intake and cancers of the breast, prostate, and colon, there are serious methodologic issues, including the difficulty in differentiating the effects of dietary fat independent of total energy intake. Reported total fat and saturated fatty acid intakes as a percentage of total energy have been declining over the past 30 years in the United States. Despite this encouraging trend, the majority of individuals--regardless of age--do not report consuming a diet that meets the levels of fat and saturated fatty acids recommended by the Dietary Guidelines for Americans. On a relative basis, saturated fat intake has gone down less than has total fat intake. Individuals of all ages who report consuming a diet with < or = 30% of energy from fat consistently have lower energy intakes. Given the increasing rates of obesity in the United States at an earlier and earlier age, dietary fat reduction may be an effective part of an overall strategy to balance energy consumption with energy needs. In each of the age/gender groups reporting consumption of < or = 30% of energy from fat and less than 10% of energy from saturated fatty acids, fat-modified foods play a more important role in their diets than for people who are consuming higher levels of fat and saturated fat. The data are clear than fat-modified foods make a more significant contribution to diets of consumers with low-fat intakes. While one cannot argue cause and effect from the results presented, the patterns of fat-modified foods/low-fat intakes are consistent. The focus on overall diet quality is often lost in the national obsession with lowering fat inta

Fruit and vegetable consumption and risk factors for cardiovascular disease

The international guidelines issued by the World Health Organization recommend reduction in dietary saturated fat and cholesterol intakes as means to prevent hypercholesterolemia and cardiovascular disease (CVD); however, only limited data are available on the benefits of fruit and vegetable consumption on CVD risk factors in a community-based population. The aim of this study was to examine whether, and to what extent, intake of fruits and vegetables is inversely associated with CVD risk factors in adults. In this population-based cross-sectional study, a representative sample of 840 Tehranian adults (male and female) aged 18 to 74 years was randomly selected in 1998. Multivariate logistic regression adjusted for lifestyle and nutritional confounders was used in 2 models. After adjusting for confounders, dietary fruit and vegetable were found to be significantly and inversely associated with CVD risk factors. Adjusted odds ratio for high low-density lipoprotein concentrations were 1.00, 0.88, 0.81, and 0.75 ( P for trend < .01) in the first model, which was adjusted for age, sex, keys score, body mass index, energy intake, smoking status, dietary cholesterol, and history of diabetes mellitus and coronary artery disease, a trend which was not appreciably altered by additional adjustment for education, physical activity, and saturated, polyunsaturated, and total fat intakes. This association was observed across categories of smoking status, physical activity, and tertiles of the Keys score. Exclusion of subjects with prevalent diabetes mellitus or coronary artery disease did not alter these results significantly. Consumption of fruits and vegetables is associated with lower concentrations of total and low-density lipoprotein cholesterol and with the risk of CVD per se in a dose-response manner.

Contemporary strategies for weight loss and cardiovascular disease risk factor modification

Because of the overweight/obesity epidemic and attendant increase in risk of chronic disease worldwide, there is a pressing need to identify effective weight loss strategies. Current recommendations for weight loss advocate a reduced-calorie dietary pattern (lower in total fat) in conjunction with regular physical activity and behavior change. This combined approach is important for long-term adherence and weight maintenance. Several large-scale clinical trials implementing different reduced-calorie dietary patterns have shown that 4 to 10 kg of weight is typically lost. The different hypocaloric dietary patterns shown to be effective include reduced-fat diets (10%–30% of calories from fat), a Mediterranean-style diet, and diets that are reduced in energy density. The weight loss achieved is accompanied by beneficial changes in cardiovascular disease risk, including the lipid and lipoprotein profile and blood pressure. This article summarizes our current understanding of effective weight loss programs.

Phytosterol Intake and Dietary Fat Reduction are Independent and Additive in their Ability to Reduce Plasma LDL Cholesterol

We studied the interrelationship of diet and plant sterols (PS) on plasma lipids, lipoproteins and carotenoids. Mildly hypercholesterolemic men (n = 13) and postmenopausal women (n = 9) underwent four randomized, crossover, double-blind, controlled feeding periods of 23 days each. The design consisted of two levels of PS (0 and 3.3 g/day) and two background diets having fat content either typical of the American diet (total and saturated fat at 33.5 and 13.2% of energy, respectively), or a Step 1 type of diet (total and saturated fat at 26.4 and 7.7% of energy, respectively). Plasma total cholesterol (TC), high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, Apo A1 and Apo B were 4.3, 5.3, 4.5, 2.8 and 2.5% lower, respectively (P <or= 0.0001; <0.0001, 0.0016, 0.0006, and 0.0069), with the Step 1 diet than with the typical American diet. Diet had no effect on TC/HDL cholesterol (P = 0.1062). Plant sterol intake lowered TC, LDL cholesterol, and Apo B by 9.0, 12.4 and 6.1% and TC/HDLC by 9.6% (P <or= 0.0001 for all), respectively, without affecting HDL cholesterol and Apo A1 (P = 0.2831 and 0.732). The PS effect in lowering plasma TC and LDL cholesterol was independent of and additive to the effect due to dietary fat reduction. Responses of plasma carotenoids to PS intake were consistent with the literature.

Conjunctival xanthoma in a blue and gold macaw (Ara ararauna)

A 17-year-old female blue and gold macaw (Ara ararauna) presented for evaluation of a discreet, conjunctival mass of the OD. No other abnormalities were found on ophthalmic or physical examination. A heterophilic leukocytosis was present on the complete blood count, and elevated aspartate aminotransferase activity, creatinine kinase activity and cholesterol were present on the plasma biochemistry panel. Surgical removal of the mass was complete and no recurrence has occurred by six months after excision. Reduction of dietary fats was recommended to reduce serum cholesterol levels and reduce the likelihood of future occurrence of xanthomas in this bird.

The content of African diets is adequate to achieve optimal efficacy with fixed-dose artemether-lumefantrine: a review of the evidence

A fixed-dose combination of artemether-lumefantrine (AL, Coartem®) has shown high efficacy, good tolerability and cost-effectiveness in adults and children with uncomplicated malaria caused by Plasmodium falciparum. Lumefantrine bioavailability is enhanced by food, particularly fat.As the fat content of sub-Saharan African meals is approximately a third that of Western countries, it raises the question of whether fat consumption by African patients is sufficient for good efficacy. Data from healthy volunteers have indicated that drinking 36 mL soya milk (containing only 1.2 g of fat) results in 90% of the lumefantrine absorption obtained with 500 mL milk (16 g fat). African diets are typically based on a carbohydrate staple (starchy root vegetables, fruit [plantain] or cereals) supplemented by soups, relishes and sauces derived from vegetables, pulses, nuts or fish. The most important sources of dietary fat in African countries are oil crops (e.g. peanuts, soya beans) and cooking oils as red palm, peanut, coconut and sesame oils. Total fat intake in the majority of subSaharan countries is estimated to be in the range 30–60 g/person/day across the whole population (average 43 g/person/day). Breast-feeding of infants up to two years of age is standard, with one study estimating a fat intake of 15–30 g fat/day from breast milk up to the age of 18 months. Weaning foods typically contain low levels of fat, and the transition from breast milk to complete weaning is associated with a marked reduction in dietary fat. Nevertheless, fat intake >10 g/day has been reported in young children post-weaning. A randomized trial in Uganda reported no difference in the efficacy of AL between patients receiving supervised meals with a fixed fat content (~23 g fat) or taking AL unsupervised, suggesting that fat intake at home was sufficient for optimal efficacy. Moreover, randomized trials in African children aged 5–59 months have shown similar high cure rates to those observed in older populations, indicating that food consumption is adequate post-weaning. In conclusion, it appears that only a very small amount of dietary fat is necessary to ensure optimal efficacy with AL and that the fat content of standard meals or breast milk in sub-Saharan Africa is adequate.

Contemporary strategies for weight loss and cardiovascular disease risk factor modification

Because of the overweight/obesity epidemic and attendant increase in risk of chronic disease worldwide, there is a pressing need to identify effective weight loss strategies. Current recommendations for weight loss advocate a reduced-calorie dietary pattern (lower in total fat) in conjunction with regular physical activity and behavior change. This combined approach is important for long-term adherence and weight maintenance. Several large-scale clinical trials implementing different reduced-calorie dietary patterns have shown that 4 to 10 kg of weight is typically lost. The different hypocaloric dietary patterns shown to be effective include reduced-fat diets (10%-30% of calories from fat), a Mediterranean-style diet, and diets that are reduced in energy density. The weight loss achieved is accompanied by beneficial changes in cardiovascular disease risk, including the lipid and lipoprotein profile and blood pressure. This article summarizes our current understanding of effective weight loss programs.

Dietary Management of Obesity

The optimal diet for prevention of weight gain, obesity, metabolic syndrome, and type 2 diabetes is fat-reduced, fiber-rich, high in low-energy density carbohydrates (fruit, vegetables, and whole grain products), and intake of energy-containing drinks is restricted. The reduction of the total fat content of ad libitum diets produces weight loss in both the short term and over periods as long as 7 years. A fat-reduced diet, combined with physical activity, reduces almost all risk factors for cardiovascular disease and reduces the incidence of type 2 diabetes. The combination of reduction of dietary fat and energy, and increased physical activity has been shown to reduce the incidence of diabetes by 58% in 2 major trials. In post hoc analyses, the reduction in dietary fat (energy density) and increase in fiber were the strongest predictors of weight loss and diabetes-protective effects. LOW-GLYCEMIC INDEX AND HIGH-PROTEIN DIETS: It remains to be shown whether a low-glycemic index diet provides any benefit to weight control beyond this. Low-carbohydrate diets may be an option for inducing weight loss in obese patients, but a very low intake of carbohydrate-rich foods is not commensurate with a healthy and palatable diet in the long term. However, there is evidence that increasing the protein content of the diet from 15% up to 20%-30%, at the expense of carbohydrates, increases the satiating effect of the diet, and induces a spontaneous weight loss, and this could turn out to be a preferred option for patients with metabolic syndrome and type 2 diabetes.

Beyond Established and Novel Risk Factors

Dyslipidemia, hypertension, and diabetes mellitus have been appropriately highlighted as established predictors of cardiovascular disease. These risk factors have become preeminent targets for influencing cardiovascular risk; their assessment, treatment, and monitoring are major emphases of clinical care, research investigation, treatment guidelines, organization position papers, and measures of physician and hospital performance. Notably, lifestyle risk factors, including dietary habits, physical inactivity, smoking, and adiposity, strongly influence the established cardiovascular risk factors and also affect novel pathways of risk such as inflammation/oxidative stress, endothelial function, thrombosis/coagulation, and arrhythmia. Furthermore, modest alterations of these lifestyle risk factors are achievable and have substantial effects on cardiovascular risk. Thus, basic lifestyle habits should be considered fundamental risk factors for cardiovascular disease. Although efforts to combat established and novel risk factors with pharmacological treatments are important and should continue, we call for a systematic rebalancing of current research, clinical care, and policy efforts to focus more on lifestyle. The rising costs of healthcare and the epidemics of overweight and obesity highlight the inadequacies of our current strategy. Substantially more resources should be directed toward research on lifestyle risk factors, their determinants, and effective interventions to change them. The clinical evaluation and treatment of dietary, physical activity, and smoking habits must become as routine and familiar as assessment of blood pressure, cholesterol, and glucose levels. Major policy initiatives and reimbursement guidelines must also be rebalanced to emphasize lifestyle risk factors. Cardiovascular diseases are leading causes of death and disability among men and women in nearly all nations.1 Identification of persons at higher or lower risk for cardiovascular events is important to facilitate effective use of resources and interventions to reduce disease burden among individuals and in society. Each of the established risk factors for cardiovascular disease—age, gender, dyslipidemia, hypertension, diabetes mellitus, and smoking—have been appropriately highlighted …

Survival analyses from the Women's Intervention Nutrition Study (WINS) evaluating dietary fat reduction and breast cancer outcome

522 Background: We previously reported five year results with follow up through October, 2003 of a phase III randomized trial where a dietary intervention targeting fat intake reduction, associated with significant weight loss, improved relapse-free survival compared to control in women with resected, early stage breast cancer receiving conventional cancer management (RR 0.79, P=0.034) (JNCI 2006;98:1767- 76). After initiating the dietary intervention with 16 visits over 8 weeks, ongoing adherence was addressed by q 3 month nutritionist contacts. Active dietary intervention and contacts with nutritionists ended in May, 2004. We now report a protocol-mandated survival analysis update. Methods: Updated survival information was obtained through October, 2007 largely through national death registries and randomization group survival differences were examined using Cox proportional hazards models in intention-to-treat analyses. Exploratory analyses examined survival by hormone receptor subgroups and active dietary intervention status. Results: Although fewer deaths were seen in the intervention group (9.1% vs. 11.1% cumulative mortality, RR 0.83) the difference was not statistically significant (P=0.146). In the 362 women with ER- and PR- disease, a significant overall survival benefit was seen for intervention group participants (7.5% vs. 18.1%, cumulative mortality, RR 0.41, P=0.003). The influence of ongoing active dietary intervention was examined by analyses censored six months after contact with nutritionists ended (for survival before and after 12/31/04). Conclusions: A dietary intervention targeting fat intake reduction did not significantly increase overall survival of women with resected breast cancer receiving conventional cancer management. Exploratory analyses suggest dietary intervention influence on survival may be greater in hormone receptor negative subgroups and during the period of active dietary intervention. Dietary Intervention Effect on Survival By Receptor Status and Active Dietary Intervention Interval Patient Group # entered Entire Period During Intervention After Intervention Ended # Deaths RR P value # Death RR P Value # Death RR P value All 2437 251 0.83 0.146 208 0.78 0.068 43 1.15 0.217 ER + 1959 183 0.88 0.146 147 0.85 0.459 36 1.08 0.221 ER − 478 68 0.68 0.059 61 0.60 0.049 7 1.57 0.599 No significant financial relationships to disclose.

OPG and sRANKL Serum Concentrations in Osteopenic, Postmenopausal Women After 2-Year Genistein Administration

RANKL and its decoy receptor osteoprotegerin (OPG) constitute a complex physiological mediator system involved in the regulation of bone resorption and may be responsible for the homeostatic mechanism of normal bone remodeling. Genistein, an isoflavone representing 1-5% of total phytoestrogen content in soybean products, may positively regulate cellular bone metabolism, but its mechanism of action on bone is not yet fully understood. We studied the serum levels of both soluble RANKL (sRANKL) and OPG and the sRANKL/OPG ratio in 389 postmenopausal women (age, 49-67 yr) with a femoral neck BMD <0.795 g/cm(2) and no significant comorbid conditions after 24-mo therapy with genistein, (n = 198; 54 mg/d) or placebo (n = 191). Both intervention and placebo contained calcium and vitamin D(3). All patients received dietary instruction in an isocaloric fat-reduced diet. In comparison with placebo, sRANKL level was lower (p < 0.001 versus placebo) and OPG higher in genistein recipients (p < 0.001 versus placebo) at 1 and 2 yr, respectively. Moreover, at the end of 24 mo, genistein produced a significant reduction in the sRANKL/OPG ratio compared with placebo (genistein = -0.021, 95% CI, -0.020 to -0.022; placebo = +0.004, 95% CI, 0.003-0.005; difference = -0.020, 95% CI, -0.015 to -0.025, p < 0.001). Our findings suggest that genistein plus calcium and vitamin D(3) as part of a healthy diet is able to positively modulate bone turnover in a cohort of osteopenic, postmenopausal women and improve sRANKL-OPG balance after 24 mo of treatment.

Effect of Low-Fat Diet on Development of Prostate Cancer and Akt Phosphorylation in the Hi-Myc Transgenic Mouse Model

This study evaluated the effect of dietary fat on prostate cancer development by using the Hi-Myc mouse transgenic prostate cancer model. Hi-Myc mice develop murine prostatic intraepithelial neoplasia (mPIN) as early as 2 to 4 weeks and invasive adenocarcinoma between 6 and 9 months due to the overexpression of human c-Myc in the mouse prostate. Three-week-old male Hi-Myc mice were placed on high-fat (HF; 42% Kcal) or low-fat (LF; 12% Kcal) diets, and equal caloric intake was maintained until euthanasia at 7 months. The number of mice that developed invasive adenocarcinoma at 7 months was 27% less in the LF diet group (12/28) compared with the HF diet group (23/33, P < 0.05). Epithelial cells in mPIN lesions in the LF group had a significantly lower proliferative index compared with epithelial cells in the HF group (21.7% versus 28.9%, P < 0.05). During the mPIN phase of carcinogenesis (4 months), the LF group had higher serum insulin-like growth factor (IGF) binding protein-1 levels (21.0 +/- 8.9 ng/mL versus 3.2 +/- 0.8 ng/mL, P < 0.05) relative to the HF group. Akt (Ser(473)) phosphorylation, Akt kinase activity, and phosphorylation of downstream targets of Akt in prostates were significantly reduced in the LF diet group compared with the HF group. We conclude that dietary fat reduction delays transition from mPIN to invasive cancer in this Myc-driven transgenic mouse model, possibly through suppression of the IGF-Akt pathway and decreased proliferation of mPIN epithelial cells.

Dietary carbohydrate restriction in type 2 diabetes mellitus and metabolic syndrome: time for a critical appraisal.

Current nutritional approaches to metabolic syndrome and type 2 diabetes generally rely on reductions in dietary fat. The success of such approaches has been limited and therapy more generally relies on pharmacology. The argument is made that a re-evaluation of the role of carbohydrate restriction, the historical and intuitive approach to the problem, may provide an alternative and possibly superior dietary strategy. The rationale is that carbohydrate restriction improves glycemic control and reduces insulin fluctuations which are primary targets. Experiments are summarized showing that carbohydrate-restricted diets are at least as effective for weight loss as low-fat diets and that substitution of fat for carbohydrate is generally beneficial for risk of cardiovascular disease. These beneficial effects of carbohydrate restriction do not require weight loss. Finally, the point is reiterated that carbohydrate restriction improves all of the features of metabolic syndrome.

Carbohydrate restriction and cardiovascular risk

Originally developed as a strategy for weight loss, diets based on restriction of carbohydrates were traditionally of concern because of the assumed increased cardiovascular risk if the carbohydrates were replaced with fat. It now appears that such diets are associated with an improvement in markers of cardiovascular risk, even with higher saturated fat intake and even in the absence of weight loss. Various evidence supports this paradigm shift: 1) carbohydrate restriction improves markers of atherogenic dyslipidemia (triglycerides, high-density lipoprotein cholesterol, apolipoprotein B-apolipoprotein A-1 ratio) and reduces the more atherogenic small, dense low-density lipoprotein cholesterol; 2) high amounts of dietary carbohydrates increase de novo fatty acid synthesis and plasma triglycerides; and 3) large, long-term studies of traditional dietary fat reduction continue to fail to demonstrate the predicted improvement in cardiovascular disease risk. Cardiovascular disease is the leading cause of morbidity and mortality in the Western world. It seems appropriate to consider carbohydrate reduction as a useful, if not the preferred, alternative to low-fat diets, which have met with limited success.