Characteristics of the diet patterns tested in the optimal macronutrient intake trial to prevent heart disease (OmniHeart): options for a heart-healthy diet

OBJECTIVE: To describe the nutrient and food composition of the diets tested in the Optimal Macronutrient Intake Trial to Prevent Heart Disease (OmniHeart). DESIGN: Two center, randomized, three-period crossover, controlled feeding trial that tested the effects of three healthful diet patterns on blood pressure, serum lipid levels, and estimated cardiovascular risk. SUBJECTS/SETTING: One hundred sixty-four participants with prehypertension and hypertension. During the 19 weeks of feeding, participants were required to consume only food prepared as part of the trial. INTERVENTION: The OmniHeart trial studied three diet patterns that differed in macronutrient composition: a carbohydrate-rich diet similar to the Dietary Approaches to Stop Hypertension diet (58% carbohydrate, 15% protein, and 27% fat), a higher protein diet that had 10% more protein and 10% less carbohydrate (48% carbohydrate, 25% protein, and 27% fat), and a higher unsaturated fat diet that had 10% more unsaturated fat and 10% less carbohydrate (48% carbohydrate, 15% protein, and 37% fat). Each diet contained 6% saturated fat and 100 to 200 mg cholesterol. Sodium was 2,300 mg at the 2,100 kcal energy level and was indexed across energy levels. Calcium, magnesium, and potassium were consistent with recommendations for the Dietary Approaches to Stop Hypertension diet and also indexed to energy levels. Each diet pattern met the major nutrient recommendations set by the Dietary Guidelines for Americans 2005. The 10% protein increase in the higher protein diet emphasized plant protein; however, meat and dairy food sources were also increased somewhat. Olive oil, canola oil, and olive oil spread were used liberally to achieve the unsaturated fat content of the higher unsaturated fat diet. The 10% reduction in carbohydrate in the higher protein diet and the higher unsaturated fat diet was achieved by replacing some fruits with vegetables, reducing sweets, and using smaller portions of grain products. All three diets reduced blood pressure, total and low-density lipoprotein cholesterol levels, and estimated coronary heart disease risk. CONCLUSIONS: The OmniHeart diet patterns offer substantial flexibility in macronutrient intake that should make it easier to eat a heart-healthy diet and reduce cardiovascular disease risk.     

Comparative review of diets for the metabolic syndrome: implications for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a significant health problem and affects 70 million adults in the United States (30% of the adult population), and an estimated 20% of these individuals have the most severe form of NAFLD-nonalcoholic steatohepatitis (NASH). The mechanisms underlying disease development and progression are awaiting clarification. Insulin resistance and obesity-related inflammation, among other possible genetic, dietary, and lifestyle factors, are thought to play a key role. A program targeting gradual weight reduction and physical exercise continues to be the gold standard of treatment for all forms of NAFLD. Even though weight loss and dietary and lifestyle changes are recommended as primary treatment for fatty liver, little to no scientific evidence is available on diet and NAFLD. This article reviews the implications of current dietary approaches, including national guidelines and popular weight-loss diets, with a focus on determining the optimal diet to prescribe for NAFLD and NASH patients. The effects of macronutrient content (carbohydrate, fat, and protein ratios) and specific food components, such as soluble fiber, n-3 fatty acids, and fructose, are discussed. The premises, effects, barriers, and issues related to current dietary guidelines and specific diets are discussed, and the question, "Will it work for the pathogenesis of NAFLD and NASH? ", is addressed.     

Carbohydrate for weight and metabolic control: Where do we stand?

Changes in lifestyle are considered to play an important role in the etiology of obesity and type 2 diabetes, and improvements in diet and physical activity are the first-choice treatment for these metabolic diseases. Since the dietary recommendations of almost 40 y ago that fat should be decreased and that carbohydrate should be increased, recommendations for a healthy diet, except for minor amendments, have not changed that much. It is generally considered that caloric restriction is more important than changes in the macronutrient composition of the diet for weight loss and body weight control. Although this is true, there is increasing evidence that changes in the macronutrient composition of the diet (decreasing carbohydrate and increasing unsaturated fats and/or protein) play a role that facilitates weight loss, increases insulin sensitivity and glucose tolerance, and improves cardiovascular risk factors, such as blood pressure, blood lipid profile, and inflammatory markers, often independent of weight loss. Low-carbohydrate diets, whether they be high in unsaturated fats and/or protein, are not recommended by the American Diabetes Association; however, despite this the Joslin Diabetes Center currently advocates a diet composition of ～40% carbohydrate, 30% fat, and 30% protein energy for overweight and obese adults with type 2 diabetes or prediabetes or those at high risk of developing type 2 diabetes. Hopefully, future studies will indicate whether diets with a more equilibrated macronutrient composition than presently recommended are more appropriate for body weight and metabolic control.     

Dietary Approaches and Health Outcomes: An Evidence Analysis Center Scoping Review

Appropriate diet can prevent, manage, or reverse noncommunicable health conditions such as obesity, cardiovascular disease, and diabetes. Consequently, the public’s interest in diet and nutrition has fueled the multi-billion-dollar weight loss industry and elevated its standing on social media and the internet. Although many dietary approaches are popular, their universal effectiveness and risks across overall populations are not clear. The objective of this scoping review was to identify and characterize systematic reviews (SRs) examining diet or fasting (intermittent energy restriction [IER]) interventions among adults who are healthy or may have chronic disease. An in-depth literature search of six databases was conducted for SRs published between January 2010 and February 2020. A total of 22,385 SRs were retrieved, and 1,017 full-text articles were screened for eligibility. Of these, 92 SRs met inclusion criteria. Covered diets were organized into 12 categories: high/restricted carbohydrate (n = 30), Mediterranean, Nordic, and Tibetan (n = 19), restricted or modified fat (n = 17), various vegetarian diets (n = 16), glycemic index (n = 13), high protein (n = 12), IER (n = 11), meal replacements (n = 11), paleolithic (n = 8), Dietary Approaches to Stop Hypretension (DASH; n = 6), Atkins, South Beach, and Zone (n = 5), and eight other brand diets (n = 4). Intermediate outcomes, such as body weight or composition and cardiometabolic, were commonly reported. Abundant evidence was found exploring dietary approaches in the general population. However, heterogeneity of diet definitions, focus on single macronutrients, and infrequent macronutrient subanalyses were observed. Based on this scoping review, the Evidence Analysis Center prioritized the need to collate evidence related to macronutrient modification, specifically restricted carbohydrate diets.     

The levels of plasma low density lipoprotein are independent of cholesterol ester transfer protein in fish-oil fed F1B hamsters

A low fat, high carbohydrate diet in combination with regular exercise is the traditional recommendation for treating diabetes. Compliance with these lifestyle modifications is less than satisfactory, however, and a high carbohydrate diet raises postprandial plasma glucose and insulin secretion, thereby increasing risk of CVD, hypertension, dyslipidemia, obesity and diabetes. Moreover, the current epidemic of diabetes and obesity has been, over the past three decades, accompanied by a significant decrease in fat consumption and an increase in carbohydrate consumption. This apparent failure of the traditional diet, from a public health point of view, indicates that alternative dietary approaches are needed. Because carbohydrate is the major secretagogue of insulin, some form of carbohydrate restriction is a prima facie candidate for dietary control of diabetes. Evidence from various randomized controlled trials in recent years has convinced us that such diets are safe and effective, at least in short-term. These data show low carbohydrate diets to be comparable or better than traditional low fat high carbohydrate diets for weight reduction, improvement in the dyslipidemia of diabetes and metabolic syndrome as well as control of blood pressure, postprandial glycemia and insulin secretion. Furthermore, the ability of low carbohydrate diets to reduce triglycerides and to increase HDL is of particular importance. Resistance to such strategies has been due, in part, to equating it with the popular Atkins diet. However, there are many variations and room for individual physician planning. Some form of low carbohydrate diet, in combination with exercise, is a viable option for patients with diabetes. However, the extreme reduction of carbohydrate of popular diets (<30 g/day) cannot be recommended for a diabetic population at this time without further study. On the other hand, the dire objections continually raised in the literature appear to have very little scientific basis. Whereas it is traditional to say that more work needs to be done, the same is true of the assumed standard low fat diets which have an ambiguous record at best. We see current trends in the national dietary recommendations as a positive sign and an appropriate move in the right direction.     

Effect of protein, unsaturated fat, and carbohydrate intakes on plasma apolipoprotein B and VLDL and LDL containing apolipoprotein C-III: results from the OmniHeart Trial

BACKGROUND: Plasma apolipoprotein B (apo B) and VLDL and LDL with apolipoprotein C-III (apo C-III) are independent risk factors for cardiovascular disease (CVD). Dietary intake affects lipoprotein concentration and composition related to those apolipoproteins. OBJECTIVE: We studied differences in apo B lipoproteins with and without apo C-III after 3 healthy diets based on the Dietary Approaches to Stop Hypertension Trial diet. DESIGN: Healthy participants (n = 162) were fed each of 3 healthy diets for 6 wk in a crossover design. Diets differed by emphasis of either carbohydrate (Carb), unsaturated fat (Unsat), or protein (Prot). Blood was collected at baseline and after diets for analysis. RESULTS: Compared with the Carb diet, the Prot diet reduced plasma apo B and triglycerides in VLDL with apo C-III (16%, P = 0.07; 11%, P = 0.05, respectively) and apo B in LDL with apo C-III (16%, P = 0.04). Compared with the Unsat diet, the Prot diet reduced triglycerides in VLDL with apo C-III (16%, P = 0.02). Compared with baseline (subjects' usual diet was higher in saturated fat), the Prot diet reduced apo B in LDL with apo C-III (11%, P = 0.05), and all 3 diets reduced plasma total apo B (6-10%, P < 0.05) and apo B in the major type of LDL, LDL without apo C-III (8-10%, P < 0.01). All 3 diets reduced the ratio of apo C-III to apo E in VLDL. CONCLUSIONS: Substituting protein for carbohydrate in the context of a healthy dietary pattern reduced atherogenic apo C-III-containing LDL and its precursor, apo C-III-containing VLDL, resulting in the most favorable profile of apo B lipoproteins. In addition, compared with a typical high-saturated fat diet, healthy diets that emphasize carbohydrate, protein, or unsaturated fat reduce plasma total and LDL apo B and produce a lower more metabolically favorable ratio of apo C-III to apo E.     

High-monounsaturated fatty acid diets lower both plasma cholesterol and triacylglycerol concentrations

BACKGROUND: Low-fat diets increase plasma triacylglycerol and decrease HDL-cholesterol concentrations, thereby potentially adversely affecting cardiovascular disease (CVD) risk. High-monounsaturated fatty acid (MUFA), cholesterol-lowering diets do not raise triacylglycerol or lower HDL cholesterol, but little is known about how peanut products, a rich source of MUFAs, affect CVD risk. OBJECTIVE: The present study compared the CVD risk profile of an Average American diet (AAD) with those of 4 cholesterol-lowering diets: an American Heart Association/National Cholesterol Education Program Step II diet and 3 high-MUFA diets [olive oil (OO), peanut oil (PO), and peanuts and peanut butter (PPB)]. DESIGN: A randomized, double-blind, 5-period crossover study design (n = 22) was used to examine the effects of the diets on serum lipids and lipoproteins: AAD [34% fat; 16% saturated fatty acids (SFAs), 11% MUFAs], Step II (25% fat; 7% SFAs, 12% MUFAs), OO (34% fat; 7% SFAs, 21% MUFAs), PO (34% fat; 7% SFAs, 17% MUFAs), and PPB (36% fat; 8% SFAs, 18% MUFAs). RESULTS: The high-MUFA diets lowered total cholesterol by 10% and LDL cholesterol by 14%. This response was comparable with that observed for the Step II diet. Triacylglycerol concentrations were 13% lower in subjects consuming the high-MUFA diets and were 11% higher with the Step II diet than with the AAD. The high-MUFA diets did not lower HDL cholesterol whereas the Step II diet lowered it by 4% compared with the AAD. The OO, PO, and PPB diets decreased CVD risk by an estimated 25%, 16%, and 21%, respectively, whereas the Step II diet lowered CVD risk by 12%. CONCLUSION: A high-MUFA, cholesterol-lowering diet may be preferable to a low-fat diet because of more favorable effects on the CVD risk profile.     

MTOR signaling and ubiquitin-proteosome gene expression in the preservation of fat free mass following high protein, calorie restricted weight loss

ABSTRACT: Caloric restriction is one of the most efficient ways to promote weight loss and is known to activate protective metabolic pathways. Frequently reported with weight loss is the undesirable consequence of fat free (lean muscle) mass loss. Weight loss diets with increased dietary protein intake are popular and may provide additional benefits through preservation of fat free mass compared to a standard protein, high carbohydrate diet. However, the precise mechanism by which a high protein diet may mitigate dietary weight loss induced reductions in fat free mass has not been fully elucidated. Maintenance of fat free mass is dependent upon nutrient stimulation of protein synthesis via the mTOR complex, although during caloric restriction a decrease (atrophy) in skeletal muscle may be driven by a homeostatic shift favouring protein catabolism. This review evaluates the relationship between the macronutrient composition of calorie restricted diets and weight loss using metabolic indicators. Specifically we evaluate the effect of increased dietary protein intake and caloric restricted diets on gene expression in skeletal muscle, particularly focusing on biosynthesis, degradation and the expression of genes in the ubiquitin-proteosome (UPP) and mTOR signaling pathways, including MuRF-1, MAFbx/atrogin-1, mTORC1, and S6K1.     

Effects of isoenergetic high-carbohydrate compared with high-fat diets on human cholesterol synthesis and expression of key regulatory genes of cholesterol metabolism

BACKGROUND: High-carbohydrate diets improve plasma cholesterol concentrations but increase triacylglycerol concentrations; the latter effect increases the risk of cardiovascular disease (CVD). Triacylglycerol concentrations increase only during very-high-carbohydrate diets consisting mainly of simple sugars. OBJECTIVE: We compared the CVD risk profile, cholesterol metabolism, and glucose tolerance of 7 healthy subjects during 2 isoenergetic diets: a high-fat, low-carbohydrate diet (HF diet) and a moderately high-carbohydrate, low-fat diet (HC diet). DESIGN: In a randomized crossover study, we measured the effects of the HF diet [40% carbohydrate and 45% fat (15% saturated, 15% monounsaturated, and 15% polyunsaturated)] and HC diet [55% carbohydrate (mainly complex) and 30% fat (10% saturated, 10% monounsaturated, and 10% polyunsaturated)] (3 wk each) on plasma lipid concentrations, oral glucose tolerance, cholesterol synthesis rate, and the messenger RNA (mRNA) concentrations of beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase, the LDL receptor, and the LDL-receptor-related protein (LRP). RESULTS: Compared with the HF diet, the HC diet lowered total, LDL, and HDL cholesterol (P < 0.05 for all) without modifying the ratio of LDL to HDL cholesterol; triacylglycerol concentrations were unchanged. Lower cholesterol concentrations occurred despite a higher cholesterol synthesis rate (P < 0.05) and higher HMG-CoA reductase mRNA concentrations (P < 0.05). LDL receptor mRNA concentrations were unchanged, LRP mRNA concentrations were lower (P < 0.01), and oral glucose tolerance was better (P < 0.05) with the HC diet. CONCLUSION: The beneficial effects of the HC diet on glucose tolerance and plasma cholesterol concentrations without increases in triacylglycerol show that this diet had favorable effects on both insulin sensitivity and the plasma lipid profile.     

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

Recent 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.     

Dietetic guidelines on food and nutrition in the secondary prevention of cardiovascular disease – evidence from systematic reviews of randomized controlled trials (second update, January 2006)

AIM: To update dietetic guidelines based on systematic review evidence on dietary advice to prevent further events in people with existing cardiovascular disease (CVD) (secondary prevention). METHODS: The Cochrane Library, MEDLINE and EMBASE were comprehensively searched to January 2005 for systematic reviews on aspects of diet and heart health. Reviews were included if they searched systematically for randomized controlled trials relating to diet and secondary prevention of CVD. Each review was critically appraised by at least two members of the UK Heart Health and Thoracic Dietitians Group. The quality and results of each review were discussed and summarized at a group meeting. RESULTS: Evidence-based strategies that reduce cardiovascular events in those with CVD include reduction in saturated fat and substitution with unsaturated fats. Individuals who have suffered a myocardial infarction may also benefit from adopting a Mediterranean type diet and increasing intake of omega 3 fats, but it is not clear whether they are beneficial for all patients with CVD. There is no systematic review evidence to support the use of antioxidant vitamins supplements, low glycaemic index diets, or homocysteine lowering therapies in this group. CONCLUSION: There remains good evidence that reducing saturated fat reduces morbidity in patients with CVD. This advice is consistent for most manifestations of CVD, with the addition of Mediterranean dietary advice and increased omega 3 fats for those who have had a myocardial infarction.     

Satiety related to 24 h diet-induced thermogenesis during high protein/carbohydrate vs high fat diets measured in a respiration chamber.

OBJECTIVE: Assessment of a possible relationship between perception of satiety and diet-induced thermogenesis, with different macronutrient compositions, in a controlled situation over 24 h. DESIGN: Two diets with different macronutrient compositions were offered to all subjects in randomized order. SETTING: The study was executed in the respiration chambers at the department of Human Biology, Maastricht University. SUBJECTS: Subjects were eight females, ages 23-33 y, BMI 23+/-3 kg/m2, recruited from University staff and students. INTERVENTIONS: Subjects were fed in energy balance, with protein/carbohydrate/fat: 29/61/10 and 9/30/61 percentage of energy, with fixed meal sizes and meal intervals, and a fixed activity protocol, during 36 h experiments in a respiration chamber. The appetite profile was assessed by questionnaires during the day and during meals. Diet induced thermogenesis was determined as part of the energy expenditure. RESULTS: Energy balance was almost complete, with non-significant deviations. Diet-Induced-Thermogenesis (DIT) was 14.6+/-2.9%, on the high protein/carbohydrate diet, and 10.5+/-3.8% on the high fat diet (P < 0.01). With the high protein/high carbohydrate diet, satiety was higher during meals (P < 0.001; P < 0.05), as well as over 24 h (P < 0.001), than with the high fat diet. Within one diet, 24 h DIT and satiety were correlated (r = 0.6; P < 0.05). The difference in DIT between the diets correlated with the differences in satiety (r = 0.8; P < 0.01). CONCLUSION: In lean women, satiety and DIT were synchronously higher with a high protein/high carbohydrate diet than with a high fat diet. Differences (due to the different macronutrient compositions) in DIT correlated with differences in satiety over 24 h.     

Estimating the Direct Effect between Dietary Macronutrients and Cardiometabolic Disease,Accounting for Mediation by Adiposity and Physical Activity

Assessing the causal effects of individual dietary macronutrients and cardiometabolic disease is challenging because distinguish direct effects from those mediated or confounded by other factors is difficult. To estimate these effects, intake of protein, carbohydrate, sugar, fat, and its subtypes were obtained using food frequency data derived from a Swedish population-based cohort (n~60,000). Data on clinical outcomes (i.e., type 2 diabetes (T2D) and cardiovascular disease (CVD) incidence) were obtained by linking health registry data. We assessed the magnitude of direct and mediated effects of diet, adiposity and physical activity on T2D and CVD using structural equation modelling (SEM). To strengthen causal inference, we used Mendelian randomization (MR) to model macronutrient intake exposures against clinical outcomes. We identified likely causal effects of genetically predicted carbohydrate intake (including sugar intake) and T2D, independent of adiposity and physical activity. Pairwise, serial- and parallel-mediational configurations yielded similar results. In the integrative genomic analyses, the candidate causal variant localized to the established T2D gene TCF7L2. These findings may be informative when considering which dietary modifications included in nutritional guidelines are most likely to elicit health-promoting effects.     

Dietary fatty acids affect plasma markers of inflammation in healthy men fed controlled diets: a randomized crossover study

BACKGROUND: The effect of individual dietary fatty acids on emerging risk factors for cardiovascular disease that are associated with subclinical inflammation is unknown. OBJECTIVE: The goal was to evaluate the role of dietary fat and specific fatty acids, especially trans fatty acids, in altering concentrations of markers of inflammation in humans fed controlled diets. DESIGN: In a randomized crossover design, 50 men consumed controlled diets for 5 wk that provided 15% of energy from protein, 39% of energy from fat, and 46% of energy from carbohydrate. Eight percent of fat or fatty acids was replaced across diets with the following: cholesterol, oleic acid, trans fatty acids (TFAs), stearic acid (STE), TFA+STE (4% of energy each), and 12:0-16:0 saturated fatty acids (LMP). RESULTS: Fibrinogen concentrations were higher after consumption of the diet enriched in stearic acid than after consumption of the carbohydrate diet. C-reactive protein concentrations were higher after consumption of the TFA diet than after consumption of the carbohydrate diet, but were not significantly different after consumption of the TFA and TFA+STE diets than after consumption of the LMP diet. Interleukin 6 concentrations were lower after consumption of the oleic acid diet than after consumption of the LMP, TFA, and STE diets. E-selectin concentrations were higher after consumption of the TFA diet than after consumption of the carbohydrate diet. Consumption of the TFA but not the TFA+STE diet resulted in higher E-selectin concentrations than did the LMP diet. CONCLUSIONS: These data provide evidence that dietary fatty acids can modulate markers of inflammation. Although stearic acid minimally affects LDL cholesterol, it does appear to increase fibrinogen concentrations.     

Effects of moderate variations in the macronutrient content of the diet on cardiovascular disease risk factors in obese patients with the metabolic syndrome

BACKGROUND: The metabolic syndrome is a cluster of abnormalities that is accompanied by a 2-fold increase in the risk of cardiovascular disease. Even if there is full agreement that lifestyle changes to induce weight loss are the first-line approach, the ideal diet for the treatment of the metabolic syndrome remains uncertain. OBJECTIVE: The objective was to compare the effects of 2 diets on cardiovascular disease risk factors in obese patients with the metabolic syndrome. DESIGN: The study was carried out in 100 patients randomly assigned to either a diet relatively rich in carbohydrate [65% of energy as carbohydrate, 13% as protein, and 22% as fat (17% as unsaturated fat)] or a diet that was low in carbohydrate and high in protein and in monounsaturated fat [48% of energy as carbohydrate, 19% as protein, and 33% as fat (24% as unsaturated fat)]. RESULTS: All 100 patients completed the 5-mo study. At the end of the study, all the components of the metabolic syndrome (except HDL, which did not change) decreased significantly in both groups. With the high-carbohydrate diet, a significant decrease in LDL-cholesterol concentrations was also observed. Although the extent of the resolution of the metabolic syndrome was not different between groups, the low-carbohydrate diet was associated with a greater decrease in the prevalence of hypertension (P < 0.05) and of hypertriacylglycerolemia (P < 0.001). CONCLUSION: Tailoring diet interventions to the specific presentation of the metabolic syndrome may be the best way of reducing the risk factors for cardiovascular disease.     

Effect of low-glycemic-index dietary advice on dietary quality and food choice in children with type 1 diabetes

BACKGROUND: The practicality of diets with a low glycemic index (GI) is controversial. Theoretically, low-GI diets may limit food choice and increase dietary fat intake, but there is little objective evidence to support such a theory. OBJECTIVE: The objective was to determine the effect of low-GI dietary advice on dietary quality and food choice in children with diabetes. DESIGN: Children aged 8-13 y with type 1 diabetes (n = 104) were recruited to a prospective, randomized study comparing the effects of traditional carbohydrate-exchange dietary advice (CHOx) with those of more flexible low-GI dietary advice (LowGI). We determined the effect on long-term macronutrient intake and food choice with the use of 3-d food diaries. RESULTS: There were no differences in reported macronutrient intakes during any of the recording periods. After 12 mo, intakes of dietary fat (33.5 +/- 5.6% and 34.2 +/- 6.7% of energy, P = 0.65), carbohydrate (48.8 +/- 5.4% and 48.6 +/- 6.5% of energy, P = 0.86), protein (17.6 +/- 2.5% and 17.3 +/- 3.7% of energy, P = 0.61), total sugars, and fiber did not differ significantly between the CHOx and LowGI groups, respectively. The average number of different carbohydrate food choices per day also did not differ significantly. Subjects in the lowest-GI quartile consumed less carbohydrate as potato and white bread, but more carbohydrate as dairy-based foods and whole-grain breads than did subjects in the highest-GI quartile. CONCLUSION: Children with diabetes who receive low-GI dietary advice do not report more limited food choices or a diet with worse macronutrient composition than do children who consume a traditional carbohydrate-exchange diet.     

Effect of meat replacement by tofu on CHD risk factors including copper induced LDL oxidation

OBJECTIVE: To investigate the effect of replacing lean meat with a soy product, tofu, on coronary heart disease risk factors including serum lipoproteins, lipoprotein (a), factor VII, fibrinogen and in vitro susceptibility of LDL to oxidation. DESIGN: A randomized cross over dietary intervention study. SETTING: Free-living individuals studied at Deakin University. SUBJECTS: Forty-five free-living healthy males aged 35 to 62 years completed the dietary intervention. Three subjects were non-compliant and excluded prior to analysis. INTERVENTIONS: A diet containing 150 grams of lean meat per day was compared to a diet containing 290 grams of tofu per day in an isocaloric and isoprotein substitution. Each dietary period was one month duration. RESULTS: Analysis of the seven-day diet record showed that diets were similar in energy, protein, carbohydrate, total fat, saturated and unsaturated fat, polyunsaturated to saturated fat ratio, alcohol and fiber. Total cholesterol and triglycerides were significantly lower, and in vitro LDL oxidation lag phase was significantly longer on the tofu diet compared to the meat diet. The hemostatic factors, factor VII and fibrinogen, and lipoprotein(a) were not significantly affected by the tofu diet. CONCLUSIONS: The increase in LDL oxidation lag phase would be expected to be associated with a decrease in coronary heart disease risk.     

Systematic review and meta-analysis of energy and macronutrient intakes during pregnancy in developed countries

Research reporting diet during pregnancy in nationally representative samples is limited. This review summarizes the dietary intakes of pregnant women in developed countries and compares them with national recommendations. A systematic search without date limits was conducted. All studies reporting the macronutrient intakes of pregnant women were considered, irrespective of design. Two authors independently identified the studies to be included and assessed the methodological quality. Nutritional adequacy was summarized, with confounding factors considered. Meta-analysis data are reported for developed countries collectively, by geographical region, and by dietary methodology. Energy and macronutrient intakes of pregnant women do not match national recommendations. Energy and fiber intakes were consistently below recommendations, while total fat and saturated fat intakes were generally above recommendations and carbohydrate and polyunsaturated fat intakes were below to borderline low compared with recommendations. A mismatch between dietary practices and macronutrient recommendations in pregnant women is widespread and not well quantified. The implications of these practices are unknown until further research compares maternal diet with short-term and long-term maternal and offspring health outcomes.