Cholesterol, coconuts, and diet on Polynesian atolls: a natural experiment: the Pukapuka and Tokelau island studies

Effect of different forms of coconut on the lipid profile in normal free-living healthy subjects: A randomized controlled trial (Phase II)

Background

It has been postulated that the lipid effects of coconut could be mediated by its fatty acids, fiber and lysine/arginine ratio. Hence, the lipid effects of coconut oil could be different from the effects of the kernel flakes or milk extract because the constituents could be different in each coconut preparation. The present research investigated the lipid effects of different modes of coconut used in food preparation.

Methods

This study involved a total of 190 participants, randomized into four groups, which received coconut oil supplement (30 ml) (n = 53), kernel flakes (30 g) (n = 52) or coconut milk powder (30 g) (n = 44) for a period of 8 weeks. The control group (n = 41) received no supplement. Lipid assays were performed at baseline and at the end of the 4th and 8th weeks. The generalized estimating equations (GEE), ANOVA, and paired and independent t-tests were used in the analysis.

Result

The age range of the participants was 25-60 years, and 52.6% of them (n = 100) were men. Coconut milk supplementation induced beneficial changes in the lipid profile in that the LDL and non-HDL levels decreased while the HDL levels increased. The subgroup whose baseline LDL level was elevated appeared to benefit most from coconut milk supplementation. Coconut oil and kernel flakes failed to induce favorable lipid changes comparable to coconut milk supplementation.

Conclusion

Differing concentrations of protein, fat and fiber in coconut preparations could possibly explain the dissimilar effects on the lipid profile caused by the different coconut preparations. The benefits of coconut milk seen in the high basal LDL subgroup warrant a detailed study.

The Lipid-Heart Hypothesis and the Keys Equation Defined the Dietary Guidelines but Ignored the Impact of Trans-Fat and High Linoleic Acid Consumption

In response to a perceived epidemic of coronary heart disease, Ancel Keys introduced the lipid-heart hypothesis in 1953 which asserted that high intakes of total fat, saturated fat, and cholesterol lead to atherosclerosis and that consuming less fat and cholesterol, and replacing saturated fat with polyunsaturated fat, would reduce serum cholesterol and consequently the risk of heart disease. Keys proposed an equation that would predict the concentration of serum cholesterol (ΔChol.) from the consumption of saturated fat (ΔS), polyunsaturated fat (ΔP), and cholesterol (ΔZ): ΔChol. = 1.2(2ΔS - ΔP) + 1.5ΔZ. However, the Keys equation conflated natural saturated fat and industrial trans-fat into a single parameter and considered only linoleic acid as the polyunsaturated fat. This ignored the widespread consumption of trans-fat and its effects on serum cholesterol and promoted an imbalance of omega-6 to omega-3 fatty acids in the diet. Numerous observational, epidemiological, interventional, and autopsy studies have failed to validate the Keys equation and the lipid-heart hypothesis. Nevertheless, these have been the cornerstone of national and international dietary guidelines which have focused disproportionately on heart disease and much less so on cancer and metabolic disorders, which have steadily increased since the adoption of this hypothesis.

Coconut oil: an overview of cardiometabolic effects and the public health burden of misinformation

Recent data from meta-analyses of randomized clinical trials (RCTs) suggest that dietary intake of coconut oil, rich in saturated fatty acids, does not result in cardiometabolic benefits, nor in improvements in anthropometric, lipid, glycemic, and subclinical inflammation parameters. Nevertheless, its consumption has surged in recent years all over the world, a phenomenon which can possibly be explained by an increasing belief among health professionals that this oil is as healthy as, or perhaps even healthier than, other oils, in addition to social network misinformation spread. The objective of this review is to present nutritional and epidemiological aspects related to coconut oil, its relationship with metabolic and cardiovascular health, as well as possible hypotheses to explain its high rate of consumption, in spite of the most recent data regarding its actual effects.

The effects of coconut oil on the cardiometabolic profile: a systematic review and meta-analysis of randomized clinical trials

Background

Despite having a 92% concentration of saturated fatty acid composition, leading to an apparently unfavorable lipid profile, body weight and glycemic effect, coconut oil is consumed worldwide. Thus, we conducted an updated systematic review and meta-analysis of randomized clinical trials (RCTs) to analyze the effect of coconut oil intake on different cardiometabolic outcomes.

Methods

We searched Medline, Embase, and LILACS for RCTs conducted prior to April 2022. We included RCTs that compared effects of coconut oil intake with other substances on anthropometric and metabolic profiles in adults published in all languages, and excluded non-randomized trials and short follow-up studies. Risk of bias was assessed with the RoB 2 tool and certainty of evidence with GRADE. Where possible, we performed meta-analyses using a random-effects model.

Results

We included seven studies in the meta-analysis (n = 515; 50% females, follow up from 4 weeks to 2 years). The amount of coconut oil consumed varied and is expressed differently among studies: 12 to 30 ml of coconut oil/day (n = 5), as part of the amount of SFAs or total daily consumed fat (n = 1), a variation of 6 to 54.4 g/day (n = 5), or as part of the total caloric energy intake (15 to 21%) (n = 6). Coconut oil intake did not significantly decrease body weight (MD -0.24 kg, 95% CI -0.83 kg to 0.34 kg), waist circumference (MD -0.64 cm, 95% CI -1.69 cm to 0.41 cm), and % body fat (-0.10%, 95% CI -0.56% to 0.36%), low-density lipoprotein cholesterol (LDL-C) (MD -1.67 mg/dL, 95% CI -6.93 to 3.59 mg/dL), and triglyceride (TG) levels (MD -0.24 mg/dL, 95% CI -5.52 to 5.04 mg/dL). However, coconut oil intake was associated with a small increase in high-density lipoprotein cholesterol (HDL-C) (MD 3.28 mg/dL, 95% CI 0.66 to 5.90 mg/dL). Overall risk of bias was high, and certainty of evidence was very-low. Study limitations include the heterogeneity of intervention methods, in addition to small samples and short follow-ups, which undermine the effects of dietary intervention in metabolic parameters.

Conclusions

Coconut oil intake revealed no clinically relevant improvement in lipid profile and body composition compared to other oils/fats. Strategies to advise the public on the consumption of other oils, not coconut oil, due to proven cardiometabolic benefits should be implemented.

Registration

PROSPERO CRD42018081461.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01685-z.

Misinformation in nutrition through the case of coconut oil: An online before-and-after study

BACKGROUND AND AIMS

Despite recent scientific evidence indicating absence of cardiometabolic benefit resulting from coconut oil intake, its consumption has increased in recent years, which can be attributed to a promotion of its use on social networks. We evaluated the patterns, reasons and beliefs related to coconut oil consumption and its perceived benefits in an online survey of a population in southern Brazil.

METHODS AND RESULTS

We conducted a before-and-after study using an 11-item online questionnaire that evaluated coconut oil consumption. In the same survey, participants who consumed coconut oil received an intervention to increase literacy about the health effects of coconut oil intake. We obtained 3160 valid responses. Among participants who consumed coconut oil (59.1%), 82.5% considered it healthy and 65.4% used it at least once a month. 81.2% coconut oil consumers did not observe any health improvements. After being exposed to the conclusions of a meta-analysis showing that coconut oil does not show superior health benefits when compared to other oils and fats, 73.5% of those who considered coconut oil healthy did not change their opinion. Among individuals who did not consume coconut oil, 47.6% considered it expensive and 11.6% deemed it unhealthy.

CONCLUSIONS

Coconut oil consumption is motivated by the responders' own beliefs in its supposed health benefits, despite what scientific research demonstrates. This highlights the difficulty in deconstructing inappropriate concepts of healthy diets that are disseminated in society.

Dietary Transitions and Health Outcomes in Four Populations - Systematic Review

IMPORTANCE

Non-communicable chronic diseases (NCDs) such as obesity, type 2 diabetes, heart disease, and cancer were rare among non-western populations with traditional diets and lifestyles. As populations transitioned toward industrialized diets and lifestyles, NCDs developed.

OBJECTIVE

We performed a systematic literature review to examine the effects of diet and lifestyle transitions on NCDs.

EVIDENCE REVIEW

We identified 22 populations that underwent a nutrition transition, eleven of which had sufficient data. Of these, we chose four populations with diverse geographies, diets and lifestyles who underwent a dietary and lifestyle transition and explored the relationship between dietary changes and health outcomes. We excluded populations with features overlapping with selected populations or with complicating factors such as inadequate data, subgroups, and different study methodologies over different periods. The selected populations were Yemenite Jews, Tokelauans, Tanushimaru Japanese, and Maasai. We also review transition data from seven excluded populations (Pima, Navajo, Aboriginal Australians, South African Natal Indians and Zulu speakers, Inuit, and Hadza) to assess for bias.

FINDINGS

The three groups that replaced saturated fats (SFA) from animal (Yemenite Jews, Maasai) or plants (Tokelau) with refined carbohydrates had negative health outcomes (e.g., increased obesity, diabetes, heart disease). Yemenites reduced SFA consumption by >40% post-transition but men's BMI increased 19% and diabetes increased ~40-fold. Tokelauans reduced fat, dramatically reduced SFA, and increased sugar intake: obesity and diabetes rose. The Tanushimaruans transitioned to more fats and less carbohydrates and used more anti-hypertensive medications; stroke and breast cancer declined while heart disease was stable. The Maasai transitioned to lower fat, SFA and higher carbohydrates and had increased BMI and diabetes. Similar patterns were observed in the seven other populations.

CONCLUSION

The nutrient category most strongly associated with negative health outcomes - especially obesity and diabetes - was sugar (increased 600-650% in Yemenite Jews and Tokelauans) and refined carbohydrates (among Maasai, total carbohydrates increased 39% in men and 362% in women), while increased calories was less strongly associated with these disorders. Across 11 populations, NCDs were associated with increased refined carbohydrates more than increased calories, reduced activity or other factors, but cannot be attributed to SFA or total fat consumption.

Tropical Oil Consumption and Cardiovascular Disease: An Umbrella Review of Systematic Reviews and Meta Analyses

The health effects of saturated fat, particularly tropical oil, on cardiovascular disease are unclear. We investigated the effect of tropical oil (palm and coconut oils), lard, and other common vegetable oils (soybean and rice bran oils) that are widely used in tropical and Asian countries on lipid profiles. We performed an umbrella review of meta-analyses and systematic reviews. Electronic databases (Medline, Scopus, Embase, and Cochrane) were searched up to December 2018 without language restriction. We identified nine meta-analyses that investigated the effect of dietary oils on lipid levels. Replacement of polyunsaturated fatty-acid-rich oils (PUFAs) and monounsaturated FA-rich oils (MUFAs) with palm oil significantly increased low-density lipoprotein cholesterol (LDL-c), by 3.43 (0.44-6.41) mg/dL and 9.18 (6.90-11.45) mg/dL, respectively, and high-density lipoprotein cholesterol (HDL-c), by 1.89 (1.23-2.55) mg/dL and 0.94 (-0.07-1.97) mg/dL, respectively. Replacement of PUFAs with coconut oil significantly increased HDL-c and total cholesterol -by 2.27 (0.93-3.6) mg/dL and 5.88 (0.21-11.55) mg/dL, respectively-but not LDL-c. Substituting lard for MUFAs and PUFAs increased LDL-c-by 8.39 (2.83-13.95) mg/dL and 9.85 (6.06-13.65) mg/dL, respectively-but not HDL-c. Soybean oil substituted for other PUFAs had no effect on lipid levels, while rice bran oil substitution decreased LDL-c. Our findings show the deleterious effect of saturated fats from animal sources on lipid profiles. Replacement of unsaturated plant-derived fats with plant-derived saturated fats slightly increases LDL-c but also increases HDL-c, which in turn may exert a neutral effect on cardiovascular health.

Effects of virgin coconut oil consumption on metabolic syndrome components and asymmetric dimethylarginine: A randomized controlled clinical trial

BACKGROUND AND AIMS

There is some promising evidence regarding the beneficial effect of coconut oil on cardiometabolic risk factors. This study aimed to assess the effects of virgin coconut oil (VCO) consumption on metabolic syndrome (MetS) components, as well as, asymmetric dimethylarginine (ADMA) in adults with MetS.

METHODS AND RESULTS

In this randomized controlled trial, 48 subjects, aged 20-50 years, with MetS were allocated into two groups; the intervention group was given 30 ml of VCO per day to substitute the same amounts of fat in their usual diet for four weeks. The control group was advised to follow their usual diet. VCO consumption significantly reduced serum levels of triglyceride (TG) (P = 0.001), very low-density lipoprotein (VLDL) (P = 0.001), and fasting blood sugar (FBS) (P = 0.015) compared to the control group. The levels of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and total cholesterol (TC) were significantly increased in the VCO group when compared to the control group (P = 0.001). Circulatory ADMA also increased in the VCO group compared to the control group (P = 0.003). No significant differences were observed in the LDL-C/HDL-C ratio, anthropometric parameters, and blood pressure measurements between the two groups at the end of the study (P > 0.05).

CONCLUSION

VCO consumption increased the values of HDL-C while reduced TG and FBS levels. Blood pressure and waist circumference did not change. However, levels of TC, LDL-C, and ADMA elevated by VCO consumption. Caution is warranted until the results of further studies become available to explain the long-term effects of VCO consumption.

REGISTRATION NUMBER

IRCT20131125015536N11.

Magnitude of Central Obesity and its Associated Factors Among Adults in Urban Areas of Northwest Ethiopia

PURPOSE

Obesity is becoming one of the most common public health problems worldwide. In particular, central obesity which indicates abnormal fat accumulation in the abdominal regions is highly associated with the risk of getting cardiometabolic diseases and their progression to end stage diseases or death. However, in developing countries, including Ethiopia less attention has been given to analyze the magnitude and associated factors of it. Therefore, we aimed to determine the prevalence of central obesity and its associated factors among adults in urban areas of Northwest Ethiopia.

METHODS

A cross-sectional study was conducted among 773 adults who lived in urban areas of Northwest Ethiopia from April 1 to May 30, 2019. Central obesity was assessed using both waist to hip ratio and waist circumference of the participants. Data were analyzed using STATA 14.0. The factors associated with central obesity were identified by binary logistic regression analyses using 95% confidence interval and the degree of association of the factors was measured using adjusted odds ratio (AOR). P-value <0.05 was used to declare statistical significance.

RESULTS

The prevalence of central obesity with waist circumference and waist to hip ratio definition criteria was 37.6% and 35.7%, respectively. According to body mass index, about 26.26% and 10.29% of the study participants were overweight and obese, respectively. A one-year increase in age (AOR=1.05; 95%CI: 1.03-1.07), being female (AOR=9.62; 95%CI: 4.84-19.12) and eating of liquid oils (AOR=2.58; 95%CI: 1.71-3.90) were found to have statistically significant variables with central obesity.

CONCLUSION

The prevalence of central obesity was relatively high in comparison with similar studies. Thus, governmental and nongovernmental organizations that work in the health system as well as health professionals should focus on the preventive measure of central obesity to control its associated disorders at an early stage.

The Effect of Coconut Oil Consumption on Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Clinical Trials

BACKGROUND

Coconut oil is high in saturated fat and may, therefore, raise serum cholesterol concentrations, but beneficial effects on other cardiovascular risk factors have also been suggested. Therefore, we conducted a systematic review of the effect of coconut oil consumption on blood lipids and other cardiovascular risk factors compared with other cooking oils using data from clinical trials.

METHODS

We searched PubMed, SCOPUS, Cochrane Registry, and Web of Science through June 2019. We selected trials that compared the effects of coconut oil consumption with other fats that lasted at least 2 weeks. Two reviewers independently screened articles, extracted data, and assessed the study quality according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The main outcomes included low-density lipoprotein cholesterol (LDL-cholesterol), high-density lipoprotein cholesterol (HDL-cholesterol), total cholesterol, triglycerides, measures of body fatness, markers of inflammation, and glycemia. Data were pooled using random-effects meta-analysis.

RESULTS

16 articles were included in the meta-analysis. Results were available from all trials on blood lipids, 8 trials on body weight, 5 trials on percentage body fat, 4 trials on waist circumference, 4 trials on fasting plasma glucose, and 5 trials on C-reactive protein. Coconut oil consumption significantly increased LDL-cholesterol by 10.47 mg/dL (95% CI: 3.01, 17.94; I² = 84%, N=16) and HDL-cholesterol by 4.00 mg/dL (95% CI: 2.26, 5.73; I² = 72%, N=16) as compared with nontropical vegetable oils. These effects remained significant after excluding nonrandomized trials, or trials of poor quality (Jadad score <3). Coconut oil consumption did not significantly affect markers of glycemia, inflammation, and adiposity as compared with nontropical vegetable oils.

CONCLUSIONS

Coconut oil consumption results in significantly higher LDL-cholesterol than nontropical vegetable oils. This should inform choices about coconut oil consumption.

Phospholipid packing defects and oxysterols in atherosclerosis: Dietary prevention and the French paradox

The research literature on atherosclerosis includes findings investigating the atherosclerotic effect of oxysterols, which are the oxidation products of cholesterol; and the literature on oxysterols refers to mechanisms by which oxysterols cause phospholipid packing defects in cell membranes. This review synthesizes these two bodies of research findings to describe how oxysterols cause phospholipid packing defects within the membranes of vascular endothelial cells, potentially increasing cell permeability of low-density lipoprotein cholesterol which may lead to atheroma formation. Exogenous sources of oxysterols are provided by dietary intake of animal-based foods that contain cholesterol oxidation products. This review proposes an explanation for the anti-atherosclerotic effect of plant-based dietary patterns, which is attributed to restriction or avoidance of dietary oxysterol intake from animal-based foods. Furthermore, raw-milk cheeses play an important role in the traditional French diet-low oxysterol content in these unheated foods may contribute to the French paradox, in which reduced coronary heart disease is associated with a diet high in saturated fat and cholesterol.

Are We Going Nuts on Coconut Oil?

PURPOSE OF REVIEW

Sales and consumption of coconut oil have been on the raise due to effective marketing strategies. Coconut oil is stated to offer various benefits including weight loss, improvement in immunity, heart health support, and memory enhancement. Also, it is often portrayed as an excellent source of medium chain triglycerides (MCTs). Here, we review the evidence behind the clinical utility of coconut oil consumption.

RECENT FINDINGS

Several studies consistently showed consumption of coconut oil increases low-density lipoprotein cholesterol (LDL-C) and thereby could increase adverse cardiovascular health. Even though coconut oil has relatively high MCT concentration, the clinical benefits of commercial MCT oils cannot be generalized to coconut oil. Until the long-term effects of coconut oil on cardiovascular health are clearly established, coconut oil should be considered as a saturated fat and its consumption should not exceed the USDA's daily recommendation (less than 10% of total calorie intake).

Virgin coconut oil is effective to treat metabolic and inflammatory dysfunction induced by high refined carbohydrate-containing diet in mice

The global rise in obesity rates is alarming since this condition is associated with chronic low-grade inflammation and secondary comorbidities as glucose intolerance, cardiovascular disease and liver damage. Therefore, a lot of dietary approaches are proposed to prevent and to treat obesity and its associated disorders. Virgin coconut oil (VCO) is well known as a functional food due to its significant amounts of medium-chain triglycerides. This study aimed to evaluate the effect of VCO on adiposity, metabolic and inflammatory dysfunctions induced by a high-refined carbohydrate-containing (HC) diet in mice. Male BALB/c mice were divided into two groups and fed with control (C) or HC diet to induce obesity for eight weeks. At the 9^th week mice fed with HC diet were randomly regrouped into four groups, and were kept this way until the 12^th week, as following: (i) HC diet alone or HC diet supplemented with three different VCO doses (ii) 1000 mg/kg, (iii) 3000 mg/kg and (iv) 9000 mg/kg. Regardless of the concentration used, VCO supplementation promoted lower adiposity and also improvement in glucose tolerance, lower serum glucose and lipid levels and decreased hepatic steatosis. Moreover, VCO intake induced a lower inflammatory response due to decreased number of leukocytes and TNF-α and IL-6 concentrations in adipose tissue, as well as reduced counts of total leukocytes, mononuclear and polymorphonuclear circulating cells. Our data showed that VCO can be considered as an interesting potential dietary approach to attenuate obesity and its metabolic and inflammatory alterations.

A Hypothesis: Moderate Consumption of Alcohol Contributes to Lower Prevalence of Type 2 Diabetes Due to the Scavenging of Alpha-Dicarbonyls by Dietary Polyphenols

The world is experiencing an epidemic of type-2-diabetes mellitus (T2DM). This has led to increased morbidity and mortality, explosive growth in health care budgets, and an even greater adverse, if indirect, impact on societies and economies of affected countries. While genetic susceptibility to T2DM is a major determinant of its prevalence, changes in lifestyles also play a role. One such change has been a transition from traditional diets characterized by low caloric and high nutrient density to calorie-rich but nutrient-poor Western diets. Given this, one solution to the epidemic of T2DM would be to abandon Western diets and revert to traditional eating patterns. However, traditional diets cannot provide enough calories for the increasing global population, so transition from traditional to Western foodstuffs appears to be irreversible. Consequently, the only practical solution to problems caused by these changes is to modify Western diets, possibly by supplementing them with functional foods containing nutrients that would compensate for these dietary deficits. I present in this study a hypothesis to explain why shifts from traditional to Western diets have been so problematic and to suggest nutrients that may counteract these adverse effects. I postulate that the components of traditional diets that may compensate for deficiencies of Westerns diets are scavengers of reactive α-dicarbonyls produced as unavoidable by-products of glucose and lipid metabolism. Most important among these scavengers are some plant secondary metabolites: polyphenols, phlorotannins, and carotenoids. They are found in alcoholic beverages and are abundant in seasonings, cocoa, coffee, tea, whole grains, pigmented vegetables, fruits, and berries.

Trending Cardiovascular Nutrition Controversies

The potential cardiovascular benefits of several trending foods and dietary patterns are still incompletely understood, and nutritional science continues to evolve. However, in the meantime, a number of controversial dietary patterns, foods, and nutrients have received significant media exposure and are mired by hype. This review addresses some of the more popular foods and dietary patterns that are promoted for cardiovascular health to provide clinicians with accurate information for patient discussions in the clinical setting.

Oxidative stability, thermal stability and acceptability of coconut oil flavored with essential oils from black pepper and ginger

The present study investigates the oxidative and thermal stability of flavoured oils developed by incorporating essential oils from black pepper and ginger to coconut oil (CNO) at concentrations of 0.1 and 1.0% (CNO_P-0.1, CNO_P-1, CNO_G-0.1, CNO_G-1). The stability of oils were assessed in terms of free fatty acids, peroxide, p-anisidine, conjugated diene and triene values and compared with CNO without any additives and a positive control with synthetic antioxidant TBHQ (CNO_T). It was found that the stability of CNO_P-1 and CNO_G-1 were comparable with CNO_T at both study conditions. The possibility of flavoured oil as a table top salad oil was explored by incorporating the same in vegetable salad and was found more acceptable than the control, on sensory evaluation. The synergetic effect of essential oil as a flavour enhancer and a powerful natural antioxidant that can slow down the oxidation of fats was established in the study.

In Silico and Wet Lab Studies Reveal the Cholesterol Lowering Efficacy of Lauric Acid, a Medium Chain Fat of Coconut Oil

The coconut oil (CO) contains 91 % of saturated fatty acids in which 72 % are medium chain fatty acids (MCFAs) like lauric, capric and caprylic acids. In contrast to animal fat, coconut oil has no cholesterol. Despite this fact, CO is sidelined among other vegetable oils due to the health hazards attributed to the saturated fatty acids. Though various medicinal effects of CO have been reported including the hypolipidemic activity, people are still confused in the consumption of this natural oil. In silico analyses and wet lab experiments have been carried out to identify the hypolipidemic properties of MCFAs and phenolic acids in CO by using different protein targets involved in cholesterol synthesis. The molecular docking studies were carried out using CDOCKER protocol in Accelery's Discovery Studio, by taking different proteins like HMG- CoA reductase and cholesterol esterase as targets and the different phytocompounds in coconut as ligands. Molecular docking highlighted the potential of lauric acid in inhibiting the protein targets involved in hyperlipidemics. Further, validation of in silico results was carried out through in vivo studies. The activity of key enzymes HMG- CoA reductase and lipoprotein lipase were found reduced in animals fed with lauric acid and CO.

Lauric acid-rich medium-chain triglycerides can substitute for other oils in cooking applications and may have limited pathogenicity

Recently, medium-chain triglycerides (MCTs) containing a large fraction of lauric acid (LA) (C12)-about 30%-have been introduced commercially for use in salad oils and in cooking applications. As compared to the long-chain fatty acids found in other cooking oils, the medium-chain fats in MCTs are far less likely to be stored in adipose tissue, do not give rise to 'ectopic fat' metabolites that promote insulin resistance and inflammation, and may be less likely to activate macrophages. When ingested, medium-chain fatty acids are rapidly oxidised in hepatic mitochondria; the resulting glut of acetyl-coenzyme A drives ketone body production and also provokes a thermogenic response. Hence, studies in animals and humans indicate that MCT ingestion is less obesogenic than comparable intakes of longer chain oils. Although LA tends to raise serum cholesterol, it has a more substantial impact on high density lipoprotein (HDL) than low density lipoprotein (LDL) in this regard, such that the ratio of total cholesterol to HDL cholesterol decreases. LA constitutes about 50% of the fatty acid content of coconut oil; south Asian and Oceanic societies which use coconut oil as their primary source of dietary fat tend to be at low cardiovascular risk. Since ketone bodies can exert neuroprotective effects, the moderate ketosis induced by regular MCT ingestion may have neuroprotective potential. As compared to traditional MCTs featuring C6-C10, laurate-rich MCTs are more feasible for use in moderate-temperature frying and tend to produce a lower but more sustained pattern of blood ketone elevation owing to the more gradual hepatic oxidation of ingested laurate.

Changes in cardiovascular disease risk factors over 30 years in Polynesians in the French Pacific Territory of Wallis Island

BACKGROUND

Wallis Island is part of a French Territory in the South Pacific. In 1980 the prevalence of hypertension and type 2 diabetes mellitus (T2DM) was low, consistent with a subsistence economy. Considerable social and economic changes have occurred over the last 30 years.

METHODS

Survey data from 1980 and 2009 were analysed by sex in 10-year age groups, and 25-64 years age-standardised to the 2008 Census. Means and prevalences were calculated for blood pressure, fasting plasma glucose, body mass index (BMI), blood cholesterol and triglycerides as risk factors contributing to cardiovascular disease.

RESULTS

During 1980-2009 there were significant increases (p < 0.05) in age-standardised means and prevalences of blood pressure and hypertension, fasting plasma glucose and T2DM, BMI and obesity, blood cholesterol (men) and triglycerides; and non-significant increases in mean diastolic blood pressure and fasting plasma glucose in women. Mean cholesterol and the prevalence of elevated cholesterol declined in women. Hypertension prevalence increased from 12% to 43% in men and from 15% to 30% in women, with 42% of the increase in men and 33% of the increase in women statistically explained by increases in BMI. T2DM increased from 2.3% to 12.2% in men and from 4.0% to 15.8% in women, with 35% of the increase in men and 26% of the increase in women statistically explained by increases in BMI.

CONCLUSIONS

Risk factors for cardiovascular disease have increased considerably in Wallis Island over the past 30 years, consistent with modernisation in way of life.

Coconut oil consumption and cardiovascular risk factors in humans

Coconut oil is being heavily promoted as a healthy oil, with benefits that include support of heart health. To assess the merits of this claim, the literature on the effect of coconut consumption on cardiovascular risk factors and outcomes in humans was reviewed. Twenty-one research papers were identified for inclusion in the review: 8 clinical trials and 13 observational studies. The majority examined the effect of coconut oil or coconut products on serum lipid profiles. Coconut oil generally raised total and low-density lipoprotein cholesterol to a greater extent than cis unsaturated plant oils, but to a lesser extent than butter. The effect of coconut consumption on the ratio of total cholesterol to high-density lipoprotein cholesterol was often not examined. Observational evidence suggests that consumption of coconut flesh or squeezed coconut in the context of traditional dietary patterns does not lead to adverse cardiovascular outcomes. However, due to large differences in dietary and lifestyle patterns, these findings cannot be applied to a typical Western diet. Overall, the weight of the evidence from intervention studies to date suggests that replacing coconut oil with cis unsaturated fats would alter blood lipid profiles in a manner consistent with a reduction in risk factors for cardiovascular disease.

A Diet Rich in Medium-Chain Fatty Acids Improves Systolic Function and Alters the Lipidomic Profile in Patients With Type 2 Diabetes: A Pilot Study

CONTEXT

Excessive cardiac long-chain fatty acid (LCFA) metabolism/storage causes cardiomyopathy in animal models of type 2 diabetes. Medium-chain fatty acids (MCFAs) are absorbed and oxidized efficiently. Data in animal models of diabetes suggest MCFAs may benefit the heart.

OBJECTIVE

Our objective was to test the effects of an MCFA-rich diet vs an LCFA-rich diet on plasma lipids, cardiac steatosis, and function in patients with type 2 diabetes.

DESIGN

This was a double-blind, randomized, 2-week matched-feeding study.

SETTING

The study included ambulatory patients in the general community.

PATIENTS

Sixteen patients, ages 37-65 years, with type 2 diabetes, an ejection fraction greater than 45%, and no other systemic disease were included.

INTERVENTION

Fourteen days of a diet rich in MCFAs or LCFAs, containing 38% as fat in total, was undertaken.

MAIN OUTCOME MEASURES

Cardiac steatosis and function were the main outcome measures, with lipidomic changes considered a secondary outcome.

RESULTS

The relatively load-independent measure of cardiac contractility, S', improved in the MCFA group (P < .05). Weight-adjusted stroke volume and cardiac output decreased in the LCFA group (both P < .05). The MCFA, but not the LCFA, diet decreased several plasma sphingolipids, ceramide, and acylcarnitines implicated in diabetic cardiomyopathy, and changes in several sphingolipids correlated with improved fasting insulins.

CONCLUSIONS

Although a diet high in MCFAs does not change cardiac steatosis, our findings suggest that the MCFA-rich diet alters the plasma lipidome and may benefit or at least not harm cardiac function and fasting insulin levels in humans with type 2 diabetes. Larger, long-term studies are needed to further evaluate these effects in less-controlled settings.

Impact of a traditional dietary supplement with coconut milk and soya milk on the lipid profile in normal free living subjects

Background. The effects of coconut fat and soya fat on serum lipids are controversial. This study was designed to investigate the lipid effects of coconut milk and soya milk supplementation on the lipid profile of free living healthy subjects. Methods. Sixty (60) healthy volunteers aged 18–57 years were given coconut milk porridge (CMP) for 5 days of the week for 8 weeks, followed by a 2-week washout period, subsequent to which they received isoenergetic soya milk porridge (SMP) for 8 weeks. Results. The LDL (low density lipoprotein) levels decreased with CMP and reached statistical significance in the total study population and in the >130 baseline LDL group. The HDL (high density lipoprotein) levels rose significantly with CMP supplementation (P = 0.000). Conclusions. We conclude that coconut fat in the form of CM does not cause a detrimental effect on the lipid profile in the general population and in fact is beneficial due to the decrease in LDL and rise in HDL. SMP will be of benefit only in those whose baseline LDL levels are elevated.

Differences in Selected Lifestyle Risk Factors for Cardiovascular Disease Between Sri Lankans in Oslo, Norway, and in Kandy, Sri Lanka

Sri Lankans in Oslo have previously been shown to have lower risk of cardiovascular disease compared with those in Kandy, Sri Lanka. Here we present lifestyle risk factors for cardiovascular diseases: frequency and type of fat consumed, frequency of fruit and vegetable intake, alcohol consumption, and leisure time physical activity between 1145 Sri Lankans living in Oslo and 678 Tamils and Sinhalese Sri Lankans living in Kandy as possible explanatory factors for the differences observed. Those in Oslo were consuming healthier fats and reported higher levels of physical activity but frequency of vegetable and fruit consumption was lower. Alcohol consumption among women was negligible. Type of fats consumed might be protective for Oslo group compared with predominantly saturated fat diet in Kandy. Higher leisure time physical activity may also be protective for the Oslo group. Higher frequency of consumption of vegetables and fruits may be beneficial in Kandy.

Glucose homeostasis can be differentially modulated by varying individual components of a western diet

Chronic overconsumption of a Western diet has been identified as a major risk factor for diabetes, yet precisely how each individual component contributes to defects in glucose homeostasis independent of consumption of other macronutrients remains unclear. Eight-week-old male Sprague Dawley rats were randomized to feeding with one of six semi-pure diets: control, processed (high advanced glycation end products/AGE), high protein, high dextrose (glucose polymer), high in saturated fat (plant origin), or high in saturated fat (animal origin). After chronic feeding for 24 weeks, body composition was determined by bioelectrical impedance spectroscopy and glucose homeostasis was assessed. When compared to the control and high AGE diets, excess consumption of the diet high in saturated fat (animal source) increased body weight and adiposity, and decreased insulin sensitivity, as defined by HOMA IR, impaired skeletal muscle insulin signaling and insulin hypersecretion in the context of increased circulating glucagon-like peptide (GLP-1). Compared to the control diet, chronic consumption of the high AGE, protein or dextrose diet increased fasting plasma glucose, decreased fasting plasma insulin and insulin secretion. These diets also reduced circulating GLP-1 concentrations. These data suggest that individual components of a western diet have differential effects in modulating glucose homeostasis and adiposity. These data provide clear evidence of a link between over-consumption of a western diet and the development of diabetes.

The carnivore connection hypothesis: revisited

The "Carnivore Connection" hypothesizes that, during human evolution, a scarcity of dietary carbohydrate in diets with low plant : animal subsistence ratios led to insulin resistance providing a survival and reproductive advantage with selection of genes for insulin resistance. The selection pressure was relaxed at the beginning of the Agricultural Revolution when large quantities of cereals first entered human diets. The "Carnivore Connection" explains the high prevalence of intrinsic insulin resistance and type 2 diabetes in populations that transition rapidly from traditional diets with a low-glycemic load, to high-carbohydrate, high-glycemic index diets that characterize modern diets. Selection pressure has been relaxed longest in European populations, explaining a lower prevalence of insulin resistance and type 2 diabetes, despite recent exposure to famine and food scarcity. Increasing obesity and habitual consumption of high-glycemic-load diets worsens insulin resistance and increases the risk of type 2 diabetes in all populations.

Influence of coconut oil administration on some hematologic and metabolic parameters in pregnant rats

OBJECTIVE

Data on the effect of coconut oil intake on various hematologic and metabolic parameters in pregnant women or animals are scanty. Hence we attempted to assess the effect of oral administration of graded doses of this edible oil during pregnancy, on various hematologic and metabolic parameters in rats.

METHODS

Groups of pregnant Sprague Dawley rats were given oral doses of 1 ml, 2 ml, and 4 ml coconut oil twice per day, respectively. Control group of rats were given tap water. Oral feeding of oil was done continuously for a period of 20 days and at the end of the study period the animals were lightly anaesthetized with ether and sacrificed to collect blood samples for analysis. Various hematologic parameters such as red blood cell (RBC) count, white blood cell (WBC) count, hemoglobin (Hg), platelets, lymphocytes, and mean corpuscular hemoglobin concentration (MCHC) were analyzed by a hematology blood analyzer, while metabolic parameters such as cholesterol, triglycerides, urea, uric acid, creatinine, and protein were analyzed by specific analytical kits. Activities of antioxidant enzyme, superoxide dismutase (SOD), glutathione peroxidase (GPX), and total antioxidant activity (TAO) were assessed by specific analytical kits. Statistical analysis of data was performed using a SPSS data analytical package.

RESULTS

Oral administration of coconut oil for 20 continuous days of pregnancy did not significantly alter any of the hematologic parameters studied, compared to control group even when the oil was administered at a relatively massive dose of 4 ml/day. Administration of coconut oil appeared to decrease WBC, Hg, platelet, and lymphocyte blood concentrations in treated rats, but the difference, however, was not statistically significant (ANOVA test; p > 0.05). However, platelet concentration was significantly lower (p < 0.05) in rats receiving 1 ml/day of coconut oil compared to control group rats. Administration of coconut oil did not alter the concentrations of protein, cholesterol, urea, triglycerides, uric acid, and creatinine in treated groups of rats significantly (Student's t-test, p > 0.05) compared to those of control rats. SOD, GPX, and TAO levels in control and treated groups were not significantly different (ANOVA test, p > 0.05) than controls.

CONCLUSIONS

We conclude that oral administration of coconut oil during pregnancy in rats, even in massive doses, does not cause any significant alterations in hematologic and metabolic parameters. More detailed studies, however, are warranted before extrapolating these results to human situations.

An open-label pilot study to assess the efficacy and safety of virgin coconut oil in reducing visceral adiposity

Introduction. This is an open-label pilot study on four weeks of virgin coconut oil (VCO) to investigate its efficacy in weight reduction and its safety of use in 20 obese but healthy Malay volunteers. Methodology. Efficacy was assessed by measuring weight and associated anthropometric parameters and lipid profile one week before and one week after VCO intake. Safety was assessed by comparing organ function tests one week before and one week after intake of VCO. Paired t-test was used to analyse any differences in all the measurable variables. Results. Only waist circumference (WC) was significantly reduced with a mean reduction of 2.86 cm or 0.97% from initial measurement (P = .02). WC reduction was only seen in males (P < .05). There was no change in the lipid profile. There was a small reduction in creatinine and alanine transferase levels. Conclusion. VCO is efficacious for WC reduction especially in males and it is safe for use in humans.

GOAT links dietary lipids with the endocrine control of energy balance

Central nervous system nutrient sensing and afferent endocrine signaling have been established as parallel systems communicating metabolic status and energy availability in vertebrates. The only afferent endocrine signal known to require modification with a fatty acid side chain is the orexigenic hormone ghrelin. We find that the ghrelin O-acyl transferase (GOAT), which is essential for ghrelin acylation, is regulated by nutrient availability, depends on specific dietary lipids as acylation substrates and links ingested lipids to energy expenditure and body fat mass. These data implicate the ghrelin-GOAT system as a signaling pathway that alerts the central nervous system to the presence of dietary calories, rather than to their absence as is commonly accepted.

Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity

The effects of dietary supplementation with coconut oil on the biochemical and anthropometric profiles of women presenting waist circumferences (WC) >88 cm (abdominal obesity) were investigated. The randomised, double-blind, clinical trial involved 40 women aged 20-40 years. Groups received daily dietary supplements comprising 30 mL of either soy bean oil (group S; n = 20) or coconut oil (group C; n = 20) over a 12-week period, during which all subjects were instructed to follow a balanced hypocaloric diet and to walk for 50 min per day. Data were collected 1 week before (T1) and 1 week after (T2) dietary intervention. Energy intake and amount of carbohydrate ingested by both groups diminished over the trial, whereas the consumption of protein and fibre increased and lipid ingestion remained unchanged. At T1 there were no differences in biochemical or anthropometric characteristics between the groups, whereas at T2 group C presented a higher level of HDL (48.7 +/- 2.4 vs. 45.00 +/- 5.6; P = 0.01) and a lower LDL:HDL ratio (2.41 +/- 0.8 vs. 3.1 +/- 0.8; P = 0.04). Reductions in BMI were observed in both groups at T2 (P < 0.05), but only group C exhibited a reduction in WC (P = 0.005). Group S presented an increase (P < 0.05) in total cholesterol, LDL and LDL:HDL ratio, whilst HDL diminished (P = 0.03). Such alterations were not observed in group C. It appears that dietetic supplementation with coconut oil does not cause dyslipidemia and seems to promote a reduction in abdominal obesity.

Trends in colorectal cancer mortality by ethnicity and socio-economic position in New Zealand, 1981-99: one country, many stories

BACKGROUND

Ethnicity and socio-economic position are important determinants of colorectal cancer (CRC) mortality. In this paper, we determine trends in colorectal cancer mortality by ethnicity and socio-economic position in New Zealand.

METHODS

Cohort studies of the entire New Zealand population for 1981-84, 1986-89, 1991-94 and 1996-99 (linking Census and mortality datasets) allowed direct determination of trends in CRC mortality by income and education. For ethnicity, we used routine unlinked Census and mortality data, but with correction factors applied for undercounting of Mâori and Pacific deaths.

RESULTS

ETHNICITY: CRC mortality trends varied markedly. There were small (10-20%) decreases among non-Mâori non-Pacific people, a 50% increase among Mâori, and up to 10-fold increase among Pacific people. By 1996-99, all three ethnic groups had similar CRC mortality. SOCIO-ECONOMIC POSITION: For females, differences in CRC mortality by education and income increased over time e.g. poor females had a 40% higher CRC mortality than rich females in 1996-99, compared with no difference in 1981-84 (p for trend 0.04). In men, increases in inequality were seen by income but not education.

CONCLUSION

The observed ethnic trends probably reflect differential trends in exposure to etiological risk factors. Social inequalities in colorectal cancer mortality appear to be increasing.

Coconut fat and serum lipoproteins: effects of partial replacement with unsaturated fats

The aim of the present study was to examine the effect of reducing saturated fat in the diet, or partly replacing it with unsaturated fat, on the serum lipoprotein profile of human subjects. The study had two intervention periods, 8 weeks (phase 1) and 52 weeks (phase 2). In phase 1, total fat was reduced from 31 to 25 % energy (polyunsaturated fatty acids (PUFA):saturated fatty acids (SFA) ratio increased from 0.2 to 0.4) by reducing the quantity of coconut fat (CF) in the diet from 17.8 to 9.3 % energy intake. In phase 2, subjects were randomised to groups A and B. In group A total fat was reduced from 25 to 20 % energy (PUFA:SFA ratio increased from 0.4 to 0.7) by reducing the quantity of CF in the diet from 9.3 to 4.7 % total energy intake. In group B, the saturated fat content in the diet was similar to group A. In addition a test fat (a mixture of soyabean oil and sesame oil, PUFA:monosaturated fatty acids ratio 2) contributed 3.3 % total energy intake and total fat contributed 24 % energy intake (PUFA:SFA ratio increased from 0.7 to 1.1). At the end of phase 1, there was a 7.7 % reduction in cholesterol (95 % CI -3.6, -12.2) and 10.8 % reduction in LDL (95 % CI -4.9, -16.5) and no significant change in HDL and triacylglycerol. At the end of phase 2, the reduction in cholesterol in both groups was only about 4 % (95 % CI -12, 3.2) partly due the concomitant rise in HDL. The reduction in LDL at 52 weeks was significantly higher in group B (group A mean reduction 11 %, 95 % CI -20.1, -2.0 and group B mean reduction 16.2 % 95 % CI -23.5, -8.9). In phase 2, triacylglycerol levels showed a mean reduction of 6.5 % in group 2A and a mean increase of 8.2 % in group 2B. The reduction of saturated fat in the diet is associated with a lipoprotein profile that would be expected to reduce cardiovascular risk. The reduction of dietary saturated fat with partial replacement of unsaturated fat brings about changes in total cholesterol, HDL- and LDL-cholesterol that are associated with a lower cardiovascular risk.

History of migration studies in biological anthropology

The earliest studies of human biological factors in migration in which a clear research design was employed date back to the early 20th century in the United States. Maurice Fishberg's study of Jewish migrants, published in 1905, antedated the classic study of Franz Boas initiated in 1908. There have been two main approaches. The first approach examined the impact of migration in relation to changing environment and the importance of environmental plasticity. For example, Fishberg reported that migrants had offspring different in stature from themselves and with differences thought to be due to improvements in the environment, although some selection of genetically determined traits was suggested. Subsequently, a number of research designs have been used, ranging from Boas's simple design of sedente (nonmigrant) adults and children compared with first- and second-generation migrants; Shapiro's extension of this study in Japanese migrants to Hawai'i; Goldstein's four-fold comparison of Mexican sedentes and their offspring in Mexico, and migrants to the USA and their offspring in the USA; and Lasker's extension of Goldstein's Mexican study by including comparison of sedentes with returning emigrants. More sophisticated designs were used by Harrison and Baker in examining altitude effects and changes in subsistence and lifestyle during the 1960s through to the 1980s. The second approach has focused on the effect of migration on gene flow. For example, the clinal variation of ABO blood groups in Europe and Australia is generally purported to result from past migration, although increasing random migration for blood groups is likely to eliminate clinal variation. Migration has usually been considered from a spatial (geographic) perspective, but more recent studies have also investigated the impact of social or occupational movement (social mobility) alone, or in combination with geographic migration, and tested whether such movements are selective or random for a number of biological traits.

Large differences in serum leptin levels between nonwesternized and westernized populations: the Kitava study

OBJECTIVES

To compare serum leptin between nonwesternized and westernized populations.

SETTING

(i) The tropical island of Kitava, Trobriand Islands, Papua New Guinea and (ii) the Northern Sweden MONICA study population. Design. Cross-sectional survey.

METHODS

Fasting levels of serum leptin were analysed in 163 randomly selected Kitavans aged 20-86 years and in 224 Swedes aged 25-74.

MAIN OUTCOME MEASURE

Mean and determinants of serum leptin.

RESULTS

Geometric mean of serum leptin in Kitavan males and females were 1.5 and 4.0 vs. 4.9 and 13.8 ng mL-1 in Swedish male and females (P < 0.0001 for both sexes). In Kitavans, observed geometric mean were close to predicted levels (1.8 ng mL(-1) for males and 4.5 ng mL-1 for females) based on multiple linear regression equations including body mass index (BMI), triceps skinfolds (TSF) and age from the Swedish population-based sample. In Kitavans serum leptin was positively related to TSF amongst both sexes and, amongst females, to BMI. In Kitavans leptin was not related to fasting serum insulin. TSF explained 55% of the variation of leptin amongst females. There was a slight age-related increase of leptin amongst males. In Kitava leptin was not related to fasting serum insulin which was substantially lower than in Sweden.

CONCLUSION

The low concentrations of serum leptin amongst Kitavans probably relates to the absence of overweight and hyperinsulinaemia. At a population level serum leptin can apparently be predicted from simple measures of adiposity.

Obesity in the Caribbean

People of African origin who live in the Caribbean share a common genetic heritage but live in socioeconomic environments that diverge widely. A cross-cultural study of males and females from Jamaica, St. Lucia and Barbados investigated the prevalence of hypertension and its environmental determinants. Standardized measurement techniques allowed comparable measurements of weight, height, waist and hip circumferences, and blood pressure. The population values for body mass index (BMI), per cent overweight (males BMI > or = 27.8 kg/m2; females BMI > or = 27.3 kg/m2) and per cent obese (males BMI > or = 31.1 kg/m2; females BMI > or = 32.3 kg/m2) are presented. Prevalence of hypertension is based on the age-adjusted total population. The gradient in per capita gross national product in Jamaica, St. Lucia and Barbados parallels the gradient in the proportions of population in those countries who are obese. BMI explained 26% of the variance in blood pressure in females and 13% in males. Obesity is a significant problem in the Caribbean, as it is in many other developing countries, and it is associated with a high prevalence of hypertension, particularly in women.

The carnivore connection: dietary carbohydrate in the evolution of NIDDM

We postulate a critical role for the quantity and quality of dietary carbohydrate in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM). Our primate ancestors ate a high-carbohydrate diet and the brain and reproductive tissues evolved a specific requirement for glucose as a source of fuel. But the Ice Ages which dominated the last two million years of human evolution brought a low-carbohydrate, high-protein diet. Certain metabolic adaptations were therefore necessary to accommodate the low glucose intake. Studies in both humans and experimental animals indicate that the adaptive (phenotypic) response to low-carbohydrate intake is insulin resistance. This provides the clue that insulin resistance is the mechanism for coping with a shortage of dietary glucose. We propose that the low-carbohydrate carnivorous diet would have disadvantaged reproduction in insulin-sensitive individuals and positively selected for individuals with insulin resistance. Natural selection would therefore result in a high proportion of people with genetically-determined insulin resistance. Other factors, such as geographic isolation, have contributed to further increases in the prevalence of the genotype in some population groups. Europeans may have a low incidence of diabetes because they were among the first to adopt agriculture and their diet has been high in carbohydrate for 10,000 years. The selection pressure for insulin resistance (i.e., a low-carbohydrate diet) was therefore relaxed much sooner in Caucasians than in other populations. Hence the prevalence of genes producing insulin resistance should be lower in the European population and any other group exposed to high-carbohydrate intake for a sufficiently long period of time.