The health effects of soy: A reference guide for health professionals

Soy is a hotly debated and widely discussed topic in the field of nutrition. However, health practitioners may be ill-equipped to counsel clients and patients about the use of soyfoods because of the enormous, and often contradictory, amount of research that has been published over the past 30 years. As interest in plant-based diets increases, there will be increased pressure for practitioners to gain a working knowledge of this area. The purpose of this review is to provide concise literature summaries (400-500 words) along with a short perspective on the current state of knowledge of a wide range of topics related to soy, from the cholesterol-lowering effects of soy protein to the impact of isoflavones on breast cancer risk. In addition to the literature summaries, general background information on soyfoods, soy protein, and isoflavones is provided. This analysis can serve as a tool for health professionals to be used when discussing soyfoods with their clients and patients.

Blood Lipid Responses to Diets Enriched with Cottonseed Oil Compared With Olive Oil in Adults with High Cholesterol in a Randomized Trial

BACKGROUND

Increasing unsaturated fat intake is beneficial for cardiovascular health, but the type of unsaturated fat to recommend remains equivocal.

OBJECTIVES

We investigated the effects of an 8-week diet intervention that was rich in either cottonseed oil (CSO; PUFA rich) or olive oil (OO; MUFA rich) on blood lipids in hypercholesterolemic adults.

METHODS

Forty-three men and women with hypercholesterolemia (53 ± 10 years; BMI, 27.6 ± 4.8 kg/m2) completed this randomized parallel clinical trial consisting of an 8-week partial outpatient feeding intervention. Participants were given meals and snacks accounting for ∼60% of their daily energy needs, with 30% of energy needs from either CSO (n = 21) or OO (n = 22). At pre- and postdiet intervention visits, participants consumed a high-SFA meal (35% of total energy needs; 70% of energy from fat). The primary outcomes of fasting cholesterol profiles and secondary outcomes of postprandial blood lipids and glycemic markers were assessed over a 5-hour period.

RESULTS

There were greater reductions from baseline to week 8 in fasting serum total cholesterol (TC; -17.0 ± 3.94 mg/dL compared with -2.18 ± 3.72 mg/dL, respectively; P = 0.008), LDL cholesterol (-19.7 ± 3.94 mg/dL compared with -5.72 ± 4.23 mg/dL, respectively; P = 0.018), non-HDL cholesterol (-20.8 mg/dL ± 4.00 compared with -6.61 ± 4.01 mg/dL, respectively; P = 0.014), and apoB (-11.8 mg/dL ± 2.37 compared with -3.10 ± 2.99 mg/dL, respectively; P = 0.05), in CSO compared with OO. There were also visit effects from baseline to week 8 for increases in HDL cholesterol (CSO, 56.5 ± 2.79 mg/dL to 60.2 ± 3.35 mg/dL, respectively; OO: 59.7 ± 2.63 mg/dL to 64.1 ± 2.24 mg/dL, respectively; P < 0.001), and decreases in the TC:HDL-cholesterol ratio (CSO, 4.30 ± 0.27 mg/dL to 3.78 ± 0.27 mg/dL, respectively; OO, 3.94 ± 0.16 mg/dL to 3.57 ± 0.11 mg/dL, respectively; P < 0.001), regardless of group assignment. In response to the high-SFA meal, there were differences in postprandial plasma glucose (P = 0.003) and triglyceride (P = 0.004) responses and a trend in nonesterified fatty acids (P = 0.11) between groups, showing protection in the postprandial state from an occasional high-SFA fat meal with CSO, but not OO, diet enrichment.

CONCLUSIONS

CSO, but not OO, diet enrichment caused substantial improvements in fasting and postprandial blood lipids and postprandial glycemia in hypercholesterolemic adults. This trial was registered at clinicaltrials.gov as NCT04397055.

Impact of Replacement of Individual Dietary SFAs on Circulating Lipids and Other Biomarkers of Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Humans

Little is known of the impact of individual SFAs and their isoenergetic substitution with other SFAs or unsaturated fatty acids (UFAs) on the prevention of cardiometabolic disease (CMD). This systematic literature review assessed the impact of such dietary substitutions on a range of fasting CMD risk markers, including lipid profile, markers of glycemic control and inflammation, and metabolic hormone concentrations. Eligible randomized controlled trials (RCTs) investigated the effect of isoenergetic replacements of individual dietary SFAs for ≥14 d on ≥1 CMD risk markers in humans. Searches of the PubMed, Embase, Scopus, and Cochrane CENTRAL databases on 14 February, 2021 identified 44 RCTs conducted in participants with a mean ± SD age of 39.9 ± 15.2 y. Studies' risk of bias was assessed using the Cochrane Risk of Bias tool 2.0 for RCTs. Random-effect meta-analyses assessed the effect of ≥3 similar dietary substitutions on the same CMD risk marker. Other dietary interventions were described in qualitative syntheses. We observed reductions in LDL-cholesterol concentrations after the replacement of palmitic acid (16:0) with UFAs (-0.36 mmol/L; 95% CI: -0.50, -0.21 mmol/L; I2 = 96.0%, n = 18 RCTs) or oleic acid (18:1n-9) (-0.16 mmol/L; 95% CI: -0.28, -0.03 mmol/L; I2 = 89.6%, n = 9 RCTs), with a similar impact on total cholesterol and apoB concentrations. No effects on other CMD risk markers, including HDL-cholesterol, triacylglycerol, glucose, insulin, or C-reactive protein concentrations, were evident. Similarly, we found no evidence of a benefit from replacing dietary stearic acid (18:0) with UFAs on CMD risk markers (n = 4 RCTs). In conclusion, the impact of replacing dietary palmitic acid with UFAs on lipid biomarkers is aligned with current public health recommendations. However, owing to the high heterogeneity and limited studies, relations between all individual SFAs and biomarkers of cardiometabolic health need further confirmation from RCTs. This systematic review was registered at www.crd.york.ac.uk/prospero/ as CRD42020084241.

Small dense low-density lipoprotein-lowering agents

Metabolic disorders, including obesity, diabetes, and hyperlipidemia, as well as cardiovascular diseases (CVD), particularly atherosclerosis, are still leading causes of death worldwide. Plasma levels of low-density lipoprotein (LDL) are currently being considered as a critical risk factor for the diseases mentioned above, especially atherosclerosis. Because of the heterogeneous nature of LDL, many studies have already been conducted on its subclasses, especially small dense LDL (sdLDL). According to available evidence, sdLDL levels can be considered as an ideal alternative to LDL levels for monitoring CVD and early diagnosis of atherosclerosis. Recently, several researchers have focused on factors that are able to decrease sdLDL levels and improve health quality. Therefore, the purpose of this study is to describe the production process of sdLDL particles and review the effects of pharmaceutical and dietary agents as well as lifestyle on sdLDL plasma levels. In brief, their mechanisms of action are discussed. Apparently, cholesterol and LDL-lowering compounds are also effective in the reduction of sdLDL levels. In addition, improving lipid profile, especially the reduction of triglyceride levels, appropriate regimen, and lifestyle can decrease sdLDL levels. Therefore, all the aforementioned parameters should be taken into consideration simultaneously in sdLDL levels reducing strategies.

Soybean oil lowers circulating cholesterol levels and coronary heart disease risk, and has no effect on markers of inflammation and oxidation

To reduce risk of coronary heart disease, replacement of saturated fats (SFAs) with polyunsaturated fats (PUFA) is recommended. Strong and concordant evidence supports this recommendation, but controversy remains. Some observational studies have reported no association between SFAs and coronary heart disease, likely because of failure to account for the macronutrient replacing SFAs, which determines the direction and strength of the observed associations. Controversy also persists about whether ω-6 (nω-6) PUFA or a high dietary ratio of nω-6 to ω-3 (nω-3) fatty acids leads to proinflammatory and pro-oxidative states. These issues are relevant to soybean oil, which is the leading edible oil consumed globally and in the United States. Soybean oil accounts for over 40% of the US intake of both essential fatty acids. We reviewed clinical and epidemiologic literature to determine the effects of soybean oil on cholesterol levels, inflammation, and oxidation. Clinical evidence indicates that soybean oil does not affect inflammatory biomarkers, nor does it increase oxidative stress. On the other hand, it has been demonstrated that when dietary SFAs are replaced with soybean oil, blood cholesterol levels are lowered. Regarding the nω-6:nω-3 dietary ratio, health agencies have consistently rejected the importance of this ratio, instead emphasizing the importance of consuming sufficient amounts of each type of fat. Thus, several lines of evidence indicate that soybean oil can positively contribute to overall health and reduction of risk of coronary heart disease.

The impact of rice bran oil consumption on the serum lipid profile in adults: a systematic review and meta-analysis of randomized controlled trials

Dyslipidemia/hyperlipidemia is recognized among the risk factors for lifestyle related diseases. A healthy diet, rich in vegetable oils such as rice bran oil (RBO), may aid to improve serum lipid levels. Thus, the aim of this study was to assess the effects of rice bran oil (RBO) consumption on serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c) and triglyceride (TG) levels in adults. The following online databases were searched for manuscripts published until October 7^th 2020: PubMed/Medline, Scopus, Clarivate Analytics' Web of Science, Cochrane Central Register of Controlled Trials, and Google Scholar. The effect sizes were expressed as weighted mean difference (WMD) with 95% confidence intervals (CI). A total of 8 eligible trials with 14 effect sizes were included in this meta-analysis. Our analysis revealed that the consumption of RBO significantly decreased serum TC (WMD: -7.29 mg/dL, 95% CI: -11.32, -3.25, P = 0.000), LDL-c (WMD: -7.62 mg/dL, 95% CI: -11.10, -4.14, P = 0.000) and TG (WMD: -9.19 mg/dL, 95% CI: -17.99, -0.38, P = 0.041) levels. So, available evidence suggests that RBO consumption can significantly decrease serum TC, LDL-c and TG levels. Hence, it may play a role in reducing dyslipidemia/hyperlipidemia risk.

Beyond Fish Oil Supplementation: The Effects of Alternative Plant Sources of Omega-3 Polyunsaturated Fatty Acids upon Lipid Indexes and Cardiometabolic Biomarkers-An Overview

Cardiovascular diseases remain a global challenge, and lipid-associated biomarkers can predict cardiovascular events. Extensive research on cardiovascular benefits of omega-3 polyunsaturated fatty acids (n3-PUFAs) is geared towards fish oil supplementation and fish-rich diets. Nevertheless, vegetarianism and veganism are becoming more popular across all segments of society, due to reasons as varied as personal, ethical and religious values, individual preferences and environment-related principles, amongst others. Due to the essentiality of PUFAs, plant sources of n3-PUFAs warrant further consideration. In this review, we have critically appraised the efficacy of plant-derived n3-PUFAs from foodstuffs and supplements upon lipid profile and selected cardiometabolic markers. Walnuts and flaxseed are the most common plant sources of n3-PUFAs, mainly alpha-linolenic acid (ALA), and feature the strongest scientific rationale for applicability into clinical practice. Furthermore, walnuts and flaxseed are sources of fibre, potassium, magnesium, and non-essential substances, including polyphenols and sterols, which in conjunction are known to ameliorate cardiovascular metabolism. ALA levels in rapeseed and soybean oils are only slight when compared to flaxseed oil. Spirulina and Chlorella, biomasses of cyanobacteria and green algae, are important sources of n3-PUFAs; however, their benefits upon cardiometabolic markers are plausibly driven by their antioxidant potential combined with their n3-PUFA content. In humans, ALA is not sufficiently bioconverted into eicosapentaenoic and docosahexaenoic acids. However, evidence suggests that plant sources of ALA are associated with favourable cardiometabolic status. ALA supplementation, or increased consumption of ALA-rich foodstuffs, combined with reduced omega-6 (n6) PUFAs intake, could improve the n3/n6 ratio and improve cardiometabolic and lipid profile.

The Antioxidant Role of Soy and Soy Foods in Human Health

Oxidative stress seems to play a role in many chronic diseases, such as cardiovascular diseases, diabetes, and some cancers. Research is always looking for effective approaches in the prevention and treatment of these pathologies with safe strategies. Given the central role of nutrition, the identification of beneficial healthy foods can be the best key to having a safe and at the same time effective approach. Soy has always aroused great scientific interest but often this attention is galvanized by the interaction with estrogen receptors and related consequences on health. However, soy, soy foods, and soy bioactive substances seem to have antioxidant properties, suggesting their role in quenching reactive oxygen species, although it was frequently mentioned but not studied in depth. The purpose of this review is to summarize the scientific evidence of the antioxidant properties of soy by identifying the human clinical trials available in the literature. A total of 58 manuscripts were individuated through the literature search for the final synthesis. Soy bioactive substances involved in redox processes appear to be multiple and their use seems promising. Other larger clinical trials with adequate standardization and adequate choice of biomarkers will fill the gap currently existing on the suggestive role of soy in antioxidant mechanisms.

Small dense low-density lipoprotein-cholesterol (sdLDL-C): Analysis, effects on cardiovascular endpoints and dietary strategies

Lipid profile screening is crucial for the prevention, evaluation and treatment of cardiovascular (CV) disease (CVD). Small dense low-density lipoprotein-cholesterol (sdLDL-C) is an emerging biomarker associated with CVD and several comorbidities. The aim of this literature review is to discuss the potential importance of sdLDL-C as a surrogate biomarker for managing CVD by explaining its pathophysiology and promising treatments. The current synthesis demonstrates the impact of sdLDL-C on CV ailments, which are related to arterial pathologies and dysregulated lipid profiles. Several drug classes used for the treatment of dyslipidemia decrease the sdLDL-C concentrations. For instance, statins, fibrates, ezetimibe, nicotinic acid, resin and orlistat are pharmacological sdLDL-C-lowering agents. Regarding nutritional strategies, simple carbohydrate types, such as fructose, are common in Western diets and should be reduced or avoided due to their potential in increasing synthesis of sdLDL-C subclasses. Dairy products, avocado, pistachios, soy-based diet (except for hydrogenated soybean oil) and corn oil seem to be suitable food choices for a therapeutic diet aiming to control sdLDL-C concentrations. However, thus far dietary supplementation with omega-3 fatty acids is unsubstantiated for decreasing sdLDL-C concentration. In conclusion, coupled with the traditional lipid profile, measurement or even the estimation of sdLDL-C as a routine screening should be encouraged, whereas more insights into the control of sdLDL-C are imperative. Appropriate clinical reference ranges for sdLDL-C are also needed.

The beneficial effects of nutraceuticals and natural products on small dense LDL levels, LDL particle number and LDL particle size: a clinical review

Cardiovascular diseases (CVDs) are globally the major causes of morbidity and mortality. Evidence shows that smaller and denser low-dense lipoprotein (sdLDL) particles are independent atherogenic risk factors for CVD due to their greater susceptibility to oxidation, and permeability in the endothelium of arterial walls. sdLDL levels are an independent risk factor and of more predictive value than total LDL-C for the assessment of coronary artery disease and metabolic syndrome. Functional food ingredients have attracted significant attention for the management of dyslipidemia and subsequently increase cardio-metabolic health. However, to date there is no study that has investigated the effect of these bioactive natural compounds on sdLDL levels. Therefore, the aim of the present review is to summarize the evidence accrued on the effect of special dietary ingredients such as omega-3 polyunsaturated fatty acids, nutraceuticals and herbal medicines on the levels of sdLDL, LDL particle number, and LDL particle size. Based on the results of the existing clinical trials this review suggests that natural products such as medicinal plants, nutraceuticals and omega-3 fatty acids can be used as adjunct or complementary therapeutic agents to reduce sdLDL levels, LDL particle numbers or increase LDL particle size and subsequently may prevent and treat CVD, with the advantage that theses natural agents are generally safe, accessible, and inexpensive.

Protection by pure and genistein fortified extra virgin olive oil, canola oil, and rice bran oil against acetic acid-induced ulcerative colitis in rats

Conjugation of genistein and dietary oils improves the anti-inflammatory and antioxidant effects of genistein on colitis in rats.

Study on the influence of palm oil on blood and liver biochemical parameters, beta-carotene and tocochromanols content as well as antioxidant activity in rats

In the ongoing discussion on the health properties of palm oil, a study of the effect a diet supplemented with palm oil on blood and liver biochemical parameters, beta-carotene and tocochromanols content as well as antioxidant activity was undertaken. Forty Wistar rats were randomly divided into five groups, fed with a diet supplemented with plant-based frying commercial fat, palm oil, 7.5% palm oil and 2.5% concentrate from palm oil and 10% of rapeseed oil, respectively. After 21 days, blood samples and livers were collected to determine beta-carotene and tocochromanols concentrations, antioxidant activity using DPPH* radical scavenging activity and TEAC methods, insulin, glucagon, serum triacyloglycerols and cholesterol levels, glucose in blood serum and glycogen in the livers. Research has shown valuable biological properties of palm oil in terms of plasma glucose, total cholesterol, low-density lipoprotein (LDL) cholesterol, and triacylglycerol concentrations which was related to the high content of beta-carotene and tocochromanols. PRACTICAL APPLICATION: Public concern over the health properties of palm oil has been growing. Therefore, this study supplements existing knowledge in this area based on experimental rat observations. In the presented research, plasma glucose was significantly reduced and no additional growth of total or LDL cholesterol, as well as triacylglycerol concentration, was observed after consuming a palm oil-based diet. Palm oil was a good source of beta-carotene and tocochromanols, which were preferentially distributed in rats' livers. Bioavailability of vitamin E-active compounds in palm oil supplemented rats' livers was relatively high as compared to the rapeseed oil group, therefore this observation complements literature in the field of tocotrienols and tocopherols. Studies have not confirmed the harmful effect of palm oil on rats, however in depth human studies appear to be a promising direction for further research.

Effects of oils and solid fats on blood lipids: a systematic review and network meta-analysis

The aim of this network meta-analysis (NMA) is to compare the effects of different oils/solid fats on blood lipids. Literature searches were performed until March 2018. Inclusion criteria were as follows: i) randomized trial (≥3 weeks study length) comparing at least two of the following oils/solid fats: safflower, sunflower, rapeseed, hempseed, flaxseed, corn, olive, soybean, palm, and coconut oil, and lard, beef-fat, and butter; ii) outcomes LDL-cholesterol (LDL-C), total cholesterol (TC), HDL-cholesterol (HDL-C), and triacylglycerols (TGs). A random dose-response (per 10% isocaloric exchange) NMA was performed and surface under the cumulative ranking curve (SUCRA) was estimated. Fifty-four trials were included in the NMA. Safflower oil had the highest SUCRA value for LDL-C (82%) and TC (90%), followed by rapeseed oil (76% for LDL-C, 85% for TC); whereas, palm oil (74%) had the highest SUCRA value for TG, and coconut oil (88%) for HDL-C. Safflower, sunflower, rapeseed, flaxseed, corn, olive, soybean, palm, and coconut oil as well beef fat were more effective in reducing LDL-C (−0.42 to −0.23 mmol/l) as compared with butter. Despite limitations in these data, our NMA findings are in line with existing evidence on the metabolic effects of fat and support current recommendations to replace high saturated-fat food with unsaturated oils.

Biological and Nutritional Properties of Palm Oil and Palmitic Acid: Effects on Health

A growing body of evidence highlights the close association between nutrition and human health. Fat is an essential macronutrient, and vegetable oils, such as palm oil, are widely used in the food industry and highly represented in the human diet. Palmitic acid, a saturated fatty acid, is the principal constituent of refined palm oil. In the last few decades, controversial studies have reported potential unhealthy effects of palm oil due to the high palmitic acid content. In this review we provide a concise and comprehensive update on the functional role of palm oil and palmitic acid in the development of obesity, type 2 diabetes mellitus, cardiovascular diseases and cancer. The atherogenic potential of palmitic acid and its stereospecific position in triacylglycerols are also discussed.

Palm Oil Consumption Increases LDL Cholesterol Compared with Vegetable Oils Low in Saturated Fat in a Meta-Analysis of Clinical Trials

BACKGROUND

Palm oil contains a high amount of saturated fat compared with most other vegetable oils, but studies have reported inconsistent effects of palm oil on blood lipids.

OBJECTIVE

We systematically reviewed the effect of palm oil consumption on blood lipids compared with other cooking oils using data from clinical trials.

METHODS

We searched PubMed and the Cochrane Library for trials of at least 2 wk duration that compared the effects of palm oil consumption with any of the predefined comparison oils: vegetable oils low in saturated fat, trans fat-containing partially hydrogenated vegetable oils, and animal fats. Data were pooled by using random-effects meta-analysis.

RESULTS

Palm oil significantly increased LDL cholesterol by 0.24 mmol/L (95% CI: 0.13, 0.35 mmol/L; I(2) = 83.2%) compared with vegetable oils low in saturated fat. This effect was observed in randomized trials (0.31 mmol/L; 95% CI: 0.20, 0.42 mmol/L) but not in nonrandomized trials (0.03 mmol/L; 95% CI: -0.15, 0.20 mmol/L; P-difference = 0.02). Among randomized trials, only modest heterogeneity in study results remained after considering the test oil dose and the comparison oil type (I(2) = 27.5%). Palm oil increased HDL cholesterol by 0.02 mmol/L (95% CI: 0.01, 0.04 mmol/L; I(2) = 49.8%) compared with vegetable oils low in saturated fat and by 0.09 mmol/L (95% CI: 0.06, 0.11 mmol/L; I(2) = 47.8%) compared with trans fat-containing oils.

CONCLUSIONS

Palm oil consumption results in higher LDL cholesterol than do vegetable oils low in saturated fat and higher HDL cholesterol than do trans fat-containing oils in humans. The effects of palm oil on blood lipids are as expected on the basis of its high saturated fat content, which supports the reduction in palm oil use by replacement with vegetable oils low in saturated and trans fat. This systematic review was registered with the PROSPERO registry at http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42012002601#.VU3wvSGeDRZ as CRD42012002601.

Atherogenic subfractions of lipoproteins in the treatment of metabolic syndrome by physical activity and diet - the RESOLVE trial

Background

We aimed to comprehensively evaluate lipoprotein profile including lipid particle size following a lifestyle intervention in metabolic syndrome (MetS) volunteers and to assess the associations between lipoprotein subfractions and carotid-intima-media-thickness (CIMT) – a surrogate indicator of atherogenesis.

Methods

100 participants (50–70 years) from the RESOLVE trial, underwent a one-year follow-up beginning with a three-week residential program combining high exercise volume (15-20 h/week), restrictive diet (-500 kcal/day), and education. For baseline references, 40 aged-matched healthy controls were recruited. Independent associations between subfractions of lipoproteins and CIMT were evaluated using a generalized estimating equations model accounting for variation in correlations between repeated measures. The lipoprotein subfractions profile was assessed using Lipoprint® electrophoresis allowing to separate: the very low-density lipoprotein (VLDL) fraction, then the intermediate-density lipoprotein (IDL) C, B and A, the low-density lipoprotein (LDL) with subfractions 1 and 2 as large LDL and subfractions 3 to 7 as small dense LDL (sdLDL), and the high density lipoprotein (HDL) subfractions categorized into large, intermediate, and small HDL. Apolipoproteins A1 and B were also measured.

Results

78 participants completed the program. At baseline, apolipoproteins B/A1, VLDL, sdLDL and small HDL were higher in MetS than in healthy controls; IDL, LDL size, large and intermediate HDL were lower. Despite time-related regains during the follow-up, lipoprotein subfractions traditionally involved in cardiovascular risk, such as sdLDL, improved immediately after the residential program with values closest to those of healthy controls. CIMT improved throughout the lifestyle intervention. Using a generalized estimating equations model, none of the subfractions of lipoproteins nor apolipoproteins were linked to CIMT.

Conclusions

Lipoprotein subfractions traditionally involved in CVR, decreased after the 3-week residential program. During a 12 month follow-up, the time-related regains remained closer to the values of healthy controls than they were at baseline. CIMT improved throughout the lifestyle intervention. However, we failed to demonstrate a link between some lipoprotein subfractions and the atherogenicity directly measured from the wall thickness of arteries (CIMT). Further investigations are required to explore the atherogenicity of lipoprotein subfractions.

Trial registration

NCT00917917

Palm oil and blood lipid-related markers of cardiovascular disease: a systematic review and meta-analysis of dietary intervention trials

BACKGROUND

Palm oil (PO) may be an unhealthy fat because of its high saturated fatty acid content.

OBJECTIVE

The objective was to assess the effect of substituting PO for other primary dietary fats on blood lipid-related markers of coronary heart disease (CHD) and cardiovascular disease (CVD).

DESIGN

We performed a systematic review and meta-analysis of dietary intervention trials. Studies were eligible if they included original data comparing PO-rich diets with other fat-rich diets and analyzed at least one of the following CHD/CVD biomarkers: total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, TC/HDL cholesterol, LDL cholesterol/HDL cholesterol, triacylglycerols, apolipoprotein A-I and B, very-low-density lipoprotein cholesterol, and lipoprotein(a).

RESULTS

Fifty-one studies were included. Intervention times ranged from 2 to 16 wk, and different fat substitutions ranged from 4% to 43%. Comparison of PO diets with diets rich in stearic acid, monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) showed significantly higher TC, LDL cholesterol, apolipoprotein B, HDL cholesterol, and apolipoprotein A-I, whereas most of the same biomarkers were significantly lower when compared with diets rich in myristic/lauric acid. Comparison of PO-rich diets with diets rich in trans fatty acids showed significantly higher concentrations of HDL cholesterol and apolipoprotein A-I and significantly lower apolipoprotein B, triacylglycerols, and TC/HDL cholesterol. Stratified and meta-regression analyses showed that the higher concentrations of TC and LDL cholesterol, when PO was substituted for MUFAs and PUFAs, were not significant in young people and in subjects with diets with a lower percentage of energy from fat.

CONCLUSIONS

Both favorable and unfavorable changes in CHD/CVD risk markers occurred when PO was substituted for the primary dietary fats, whereas only favorable changes occurred when PO was substituted for trans fatty acids. Additional studies are needed to provide guidance for policymaking.

Pigmented rice bran and plant sterol combination reduces serum lipids in overweight and obese adults

OBJECTIVE

This study investigated the dietary effect of including pigmented rice bran with or without plant sterols on lipid profiles during energy restriction-induced weight loss in overweight and obese adults not taking cholesterol-lowering medication. In addition, the study examined the effect of intervention on biomarkers of oxidative stress and inflammation.

METHODS

A group of 24 overweight and obese adults (age: 43 ± 6 years, body mass index 32 ± 1 kg/m(2), 18 females) were randomized to a 25% calorie-restricted diet containing either pigmented rice bran (RB) or the RB with addition of plant sterols (RB+PS) snack bars for 8 weeks. The individualized nutrient-balanced diet contained ∼70% of daily energy needs assessed from indirect calorimetry measured resting energy expenditure (EE) and physical activity-related EE assessed using accelerometry. Anthropometrics, blood pressure, blood lipids, glucose, urinary F2-isoprostanes, C-reactive protein, insulin, and leptin were measured at baseline and after 8 weeks of intervention.

RESULTS

Participants lost approximately 4.7 ± 2.2 kg (p < 0.001). Weight loss was not significant between the RB+PS and RB group (p = 0.056). Changes in body fat corresponded to changes in body weight. Average decrease in total cholesterol was significantly higher in the RB+PS group than in the RB group (difference 36 ± 25 g/dL vs 7 ± 16 g/dL; p = 0.044). A similar pattern was observed for the decrease in low-density lipoprotein (LDL) cholesterol (difference 22.3 ± 25.2 g/dL vs 4.4 ± 18.9 g/dL; p = 0.062). Changes in systolic blood pressure, serum levels of leptin, and F2-isoprostanes were significant between baseline values and after 8 weeks on the diet in both groups (p < 0.05) but did not differ between the 2 groups.

CONCLUSIONS

A nutrient-balanced and energy-restricted diet supplemented with rice bran and plant sterols resulted in a significant decrease in total and LDL cholesterol in overweight and obese adults.

Rice brans, rice bran oils, and rice hulls: composition, food and industrial uses, and bioactivities in humans, animals, and cells

Rice plants produce bioactive rice brans and hulls that have been reported to have numerous health-promoting effects in cells, animals, and humans. The main objective of this review is to consolidate and integrate the widely scattered information on the composition and the antioxidative, anti-inflammatory, and immunostimulating effects of rice brans from different rice cultivars, rice bran oils derived from rice brans, rice hulls, liquid rice hull smoke derived from rice hulls, and some of their bioactive compounds. As part of this effort, this paper also presents brief summaries on the preparation of health-promoting foods including bread, corn flakes, frankfurters, ice cream, noodles, pasta, tortillas, and zero-trans-fat shortening as well as industrial products such bioethanol and biodiesel fuels. Also covered are antibiotic, antiallergic, anticarcinogenic, antidiabetic, cardiovascular, allelochemical, and other beneficial effects and the mechanisms of the bioactivities. The results show that food-compatible and safe formulations with desirable nutritional and biological properties can be used to develop new multifunctional foods as well as bioethanol and biodiesel fuel. The overlapping aspects are expected to contribute to a better understanding of the potential impact of the described health-promoting potential of the rice-derived brans, oils, and hulls in food and medicine. Such an understanding will enhance nutrition and health and benefit the agricultural and industrial economies.