The diet-heart hypothesis, obesity and diabetes

Human feeding studies show that dietary fat quality, but not total fat intake, influences levels of low-density lipoprotein (LDL) cholesterol. Metaanalyses indicate an association with reduced coronary heart disease (CHD) risk when saturated fatty acid is replaced with polyunsaturated fatty acid or with low-glycaemic index carbohydrates. A meta-analysis of eight small trials supports this benefit. Secular trends in populations that modified fat intake and quality show a consistent reduction in LDL  cholesterol levels and CHD risk. The increase in obesity and diabetes in many developed countries does not track consistently with the  implementation of dietary guidelines aimed at lowering fat intake. Obesity is more likely to be due to increases in total energy intake, coupled with an increasingly sedentary lifestyle. However, cohort studies indicate that poor dietary quality is associated with future weight gain. Both cohort studies and secular trends implicate the increased consumption of sugar-sweetened beverages as being associated with obesity, diabetes and cardiovascular disease. Weight reduction can be achieved with a range of energy-restricted diets, including low-fat, high-carbohydrate diets and low-carbohydrate, high-fat diets. Metabolic benefits are proportional to the degree of weight reduction, irrespective of the dietary approach used. The prevention of CHD requires an emphasis on fat quality, rather than fat quantity, while the prevention of obesity and diabetes requires a focus on energy balance and carbohydrate quality

Serum cholesterol as a risk factor for coronary heart disease revisited

The biology of lipoproteins and lipoprotein particles as mediators of  atherosclerosis has been documented extensively. Numerous prospective epidemiological studies have shown a robust relationship between  low-density lipoprotein (LDL) cholesterol, or particles bearing apolipoprotein B, and increased risk of coronary heart disease (CHD); and between  high-density lipoprotein (HDL) cholesterol or particles bearing  apolipoprotein A1, and decreased risk. These relationships are present across the age spectrum and in both sexes. The causality of LDL  cholesterol for CHD has been established by the clinical trials on cholesterol lowering and the Mendelian randomisation studies. However, clinical trials that focus on raising HDL cholesterol, or lowering triglycerides, have yielded mixed results, and the Mendelian randomisation studies have generally not supported causality. Research on the effects of diet on serum  cholesterol led to public health guidelines, whose implementation withinthe last five decades was accompanied by lower population cholesterol levels and CHD burden in all of the countries studied. Over the last three decades, the favourable trends in cholesterol levels and CHD have been supported by the increasing use of statin drugs and improved treatments for myocardial infarction

Hypercholesterolaemia in a rural white population and its relationship with other coronary risk factors

The risk factor and dietary associations of hypercholesterolaemia were analysed. Twenty per cent of the 6332 respondents aged 20 - 64 years in the Coronary Risk Factor Study (CORIS) were considered hypercholesterolaemic (i.e. above the 80th percentile). In this sample only 13,4% of men and 6,7% of women were on treatment, and only 32,7% and 37,1% respectively had 'desirable' high-density lipoprotein cholesterol levels. Hypercholesterolaemia was significantly associated with a personal or family history of coronary heart disease, hypertension, smoking, obesity and. hyperuricaemia. Analysis of the dietary intakes of a 15% subsample of the total population revealed no significant differences between high- and lowrisk subjects in intake of dietary fats and cholesterol. However, high-risk subjects consumed significantly more animal protein and significantly less dietary fibre than those with a low cholesterol level. These findings reflect a subpopulation at high risk of coronary heart disease. Their risk can be reduced to some extent by population strategies towards healthier lifestyles; ultimately the high-risk individuals have to be identified and appropriately treated. S Afr Med J 1990; 78: 85-8

Health actions and disease patterns related to coronary heart disease in the coloured population of the Cape Peninsula

The health-related behaviour of the Cape Peninsula coloured population, which has been shown to have an adverse coronary heart disease (CHO) risk factor profile, is reported. Private medical services were used most often by participants: 54,1% and 51,6% of males and females respectively had made use of these services during the preceding year. Only 17,9% and 21,8% of males and females respectively had attended day hospitals during the year. Blood pressures were measured in 43,8% and 57,1% of male and female participants respectively during the year preceding the study. The results indicated the need for the measurement of blood pressure to determine the true prevalence of hypertension, since patient reporting of the condition was inaccurate. Attempts to give up smoking had been made by 44,4% of male and 47,1% of female smokers. About 75% of the participants were found to have hypercholesterolaemia, yet their knowledge of the prudent diet was poor and few reported appropriate dietary modifications to protect against CHO. Frequent reporting of hypercholesterolaemia, hypertension and constipation by the study population highlights the need for dietary education. Mortality rates (MRs) for CHO and cerebrovascular disease (CVO) for the coloured and the white populations were compared. In all age groups white males had higher MRs for CHO than coloured males, while coloured females older than 34 years had higher rates than their white counterparts. The coloured population had MRs for CVO that were higher than those of whites.S Afr Med J 1990; 78: 73-7

The relationship between dietary factors and serum cholesterol values in the coloured population of the Cape Peninsula

A cross-sectional study of 976 coloured subjects aged 15 -64 years identified a population consuming a typical Western diet. Nutrient intake, determined by the 24-hour dietary recall method, reflected a diet high in fat (37% of total energy intake) and animal protein and a polyunsaturated/saturated fatly acid ratio of 0,85. Only 32,2% of men and 27,5% of women consumed a prudent diet (Keys score < 28). The influence of this Western diet on serum total cholesterol (TC) levels was seen to be marked whe'n participants with a high risk of developing coronary heart disease (CHD) were compared with those with a TC level putting them at low risk; the former consumed significantly more saturated fat and had a higher mean Keys score. Multiple linear regression analysis on TC levels of men identified six variables that explained 26,9% of the variation of TC. These were body mass index, age, the inverse of the polyunsaturated fat intake, saturated fat intake, polyunsaturated/saturated fat ratio and cholesterol intake. For women only three variables (age, the inverse of the polyunsaturated/saturated fat ratio, and body mass index) explained 30,2% of the variation of TC. Promotion of the prudent diet to lower TC levels of the coloured population of the Cape Peninsula is an increasingly urgent priority.S Afr Med J 1990; 78: 63-67

Women and Heart Disease: Neglected Directions for Future Research

Before age 65, women have less heart disease than men. For many years, estrogen was the most popular explanation for this female advantage, and observational studies through the 1980s showed a lower risk of heart attacks in postmenopausal women taking “replacement” estrogen. But the Women’s Health Initiative (WHI), the first placebo-controlled trials of hormone therapy with the size and statistical power necessary to study clinical cardiovascular outcomes, did not confirm the hormone-healthy heart hypothesis. Now, at least 5 years later, the most unexpected WHI result may be how resilient the estrogen hypothesis has been. Where, beyond estrogen therapy, should we go from here to explain the striking sex differences in heart disease rates? A broader spectrum of research about the female cardiovascular advantage and its translation is needed

Probable tacrolimus toxicity from tibolone co-administration in a woman: a case report

Introduction: Tibolone is a synthetic steroid, used with increasing frequency to treat symptoms of menopause, including patients with solid-organ transplants who are taking concurrent immune suppression. To the best of our knowledge, there are no reported drug interactions between tibolone and tacrolimus, one of the principal immune suppressants used in kidney transplantation. Case presentation: We report the case of a 49-year-old Caucasian woman who had received a kidney transplant and who developed acute kidney injury secondary to tacrolimus toxicity 10 days after starting tibolone therapy. No alternative causes were found. Tibolone is known to be a weak competitive inhibitor of CYP3A4, which is involved in tacrolimus metabolism. Conclusions: Despite a careful evaluation, no alternative reason was found for the acute kidney injury, and her kidney function returned to the previous baseline within several days of cessation of the medication, and with no other specific treatment. Using the Drug Interaction Probability Scale we conclude that she experienced a probable drug interaction. We believe that transplant clinicians should utilise frequent therapeutic drug monitoring of tacrolimus in patients starting or stopping tibolone therapy

Decline in breast cancer incidence due to removal of promoter: combination estrogen plus progestin

Combination estrogen plus progestin causes breast cancer. In light of this causal relation, the rapid decline in breast cancer incidence noted in 2003, following an earlier and slower reduction in incidence from 1999, raises important issues regarding the proportion of this decline that may be due to a reduction in the use of combination therapy by postmenopausal women. The context of these national trends is reviewed and the strong link to the use of hormone therapy is discussed, after noting that screening cannot explain any substantial component of these trends. The rapid decrease in incidence, most evident among women aged 50 to 69 years and in estrogen receptor positive tumors, that parallels the decline in combination hormone use is consistent with a promoter effect for estrogen plus progestins

Kefir consumption does not alter plasma lipid levels or cholesterol fractional synthesis rates relative to milk in hyperlipidemic men: a randomized controlled trial [ISRCTN10820810]

BACKGROUND: Fermented milk products have been shown to affect serum cholesterol concentrations in humans. Kefir, a fermented milk product, has been traditionally consumed for its potential health benefits but has to date not been studied for its hypocholesterolemic properties. METHODS: Thirteen healthy mildly hypercholesterolemic male subjects consumed a dairy supplement in randomized crossover trial for 2 periods of 4 wk each. Subjects were blinded to the dairy supplement consumed. Blood samples were collected at baseline and after 4 wk of supplementation for measurement of plasma total, low-density lipoprotein, and high-density lipoprotein cholesterol and triglyceride concentrations, as well as fatty acid profile and cholesterol synthesis rate. Fecal samples were collected at baseline and after 2 and 4 wk of supplementation for determination of fecal short chain fatty acid level and bacterial content. RESULTS: Kefir had no effect on total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol or triglyceride concentrations nor on cholesterol fractional synthesis rates after 4 wk of supplementation. No significant change on plasma fatty acid levels was observed with diet. However, both kefir and milk increased (p < 0.05) fecal isobutyric, isovaleric and propionic acids as well as the total amount of fecal short chain fatty acids. Kefir supplementation resulted in increased fecal bacterial content in the majority of the subjects. CONCLUSIONS: Since kefir consumption did not result in lowered plasma lipid concentrations, the results of this study do not support consumption of kefir as a cholesterol-lowering agent