Diet and haemostasis: time for nutrition science to get more involved

A systematic review of randomized controlled trials related to the effects of garlic supplementation on platelet aggregation

The increment of platelet aggregation factors has been considered a key phenomenon in atherosclerosis. Studies have shown that garlic (Allium sativum) is associated with a reduction in platelet aggregation and thrombosis. Hence, the present systematic review was conducted to evaluate the effect of garlic on platelet aggregation. All randomized controlled trials (RCTs) with keywords related to garlic and platelet aggregation were thoroughly searched in electronic databases including PubMed, Scopus, ISI Web of Science, and Google Scholar up to January 2021. Moreover, the references of all related articles were screened to discover more relevant studies. The quality of each study was reported based on Cochrane Collaboration's tool. In total, 12 studies met the inclusion criteria from 18,235 identified articles (including 595 participants). Most of the studies assessed platelet aggregation in response to different inducers. Of the 12 clinical trials, six studies depicted the beneficial effect of garlic on reducing platelet aggregation. The summary of the quality assessment indicated that most of the studies had high-quality scores. Regarding the small number of RCTs and heterogeneity between studies, it is impossible to make a proper conclusion about the impacts of garlic on platelet aggregation. Therefore, further precise trials with a standard design are necessary to validate the anti-thrombotic effect of garlic.

Fibrinogen concentration and its role in CVD risk in black South Africans – effect of urbanisation

The aim of this study was to investigate correlates of fibrinogen concentration in black South Africans, as well as its association with cardiovascular disease (CVD) risk and whether urbanisation influences this association. A total of 1,006 rural and 1,004 urban black South Africans from the PURE study were cross-sectionally analysed. The association of fibrinogen with CVD risk was determined by investigating the association of fibrinogen with other CVD risk markers as well as with predicted CVD risk using the Reynolds Risk score. The rural group had a significantly higher fibrinogen concentration than the urban group, despite higher levels of risk factors and increased predicted CVD risk in the urban group. Increased levels of CVD risk factors were, however, still associated with increased fibrinogen concentration. Fibrinogen correlated significantly, but weakly, with overall predicted CVD risk. This correlation was stronger in the urban than in the rural group. Multiple regression analysis showed that a smaller percentage of the variance in fibrinogen is explained by the traditional CVD risk factors in the rural than in the urban group. In conclusion, fibrinogen is weakly associated with CVD risk (predicted overall risk as well with individual risk factors) in black South Africans, and is related to the degree of urbanisation. Increased fibrinogen concentration, in black South Africans, especially in rural areas, is largely unexplained, and likely not strongly correlated with traditional CVD-related lifestyle and pathophysiological processes. This does, however, not exclude the possibility that once increased, the fibrinogen concentration contributes to future development of CVD.

Diet and haemostatic processes

Diet plays an important role in the primary and secondary prevention of cardiovascular disease. The growing perception that abnormal haemostatic processes of coagulation, platelet aggregation and fibrinolysis contribute to cardiovascular disease aetiology motivated this review on the relationships of diet, specific foods and nutrients with haemostatic function. Functional endpoints that reflect the function and status of some of these processes and which can be measured in dietary trials are identified. The effects of energy intake and expenditure, alcohol, total fat and specific fatty acids, non-starch polysaccharides (dietary fibre), antioxidant nutrients and some foods on a variety of haemostatic markers are reviewed. The results indicate that the prudent low-fat, high-fibre diet and maintenance of ideal body weight recommended to protect against and treat hyperlipidaemia and coronary heart disease will also benefit haemostatic profiles. It is concluded that more research on specific effects is needed for improved recommendations on a population level for prevention of cardiovascular disease.

The nutrition and health transition in the North West Province of South Africa: a review of the THUSA (Transition and Health during Urbanisation of South Africans) study

Objective

To describe how urbanisation influences the nutrition and health transition in South Africa by using data from the THUSA (Transition and Health during Urbanisation of South Africans) study.

Design

The THUSA study was a cross-sectional, comparative, population-based survey.

Setting

The North West Province of South Africa.

Subjects

In total, 1854 apparently healthy volunteers, men and women aged 15 years and older, from 37 randomly selected sites. Pregnant and lactating women, those with diagnosed chronic diseases and taking medication, with acute infections or inebriated were excluded but screened for hypertension and diabetes mellitus. Subjects were stratified into five groups representing different levels of urbanisation in rural and urban areas: namely, deep rural, farms, squatter camps, townships and towns/cities.Outcome measures and methods: Socio-economic and education profiles, dietary patterns, nutrient intakes, anthropometric and biochemical nutrition status, physical and mental health indicators, and risk factors for non-communicable diseases (NCDs) were measured using questionnaires developed or adapted and validated for this population, as well as appropriate, standardised methods for the biochemical analyses of biological samples.

Results

Subjects from the rural groups had lower household incomes, less formal education, were shorter and had lower body mass indices than those in the urban groups. Urban subjects consumed less maize porridge but more fruits, vegetables, animal-derived foods and fats and oils than rural subjects. Comparing women from rural group 1 with the urban group 5, the following shifts in nutrient intakes were observed: % energy from carbohydrates, 67.4 to 57.3; from fats, 23.6 to 31.8; from protein, 11.4 to 13.4 (with an increase in animal protein from 22.2 to 42.6 g day-1); dietary fibre, 15.8 to 17.7 g day-1; calcium, 348 to 512 mg day-1; iron from 8.4 to 10.4 mg day-1; vitamin A from 573 to 1246 μg retinol equivalents day-1; and ascorbic acid from 30 to 83 mg day-1. Serum total cholesterol, low-density lipoprotein cholesterol and plasma fibrinogen increased significantly across groups; systolic blood pressure >140 mmHg was observed in 10.4–34.8% of subjects in different groups and diabetes mellitus in 0.8–6.0% of subjects. Women in groups 1 to 5 had overweight plus obesity rates of 48, 53, 47, 61 and 61%, showing an increase with urbanisation. Subjects from group 2 (farm dwellers) showed the highest scores of psychopathology and the lowest scores of psychological well-being. The same subjects consistently showed the lowest nutrition status.

Conclusions

Urbanisation of Africans in the North West Province is accompanied by an improvement in micronutrient intakes and status, but also by increases in overweight, obesity and several risk factors for NCDs. It is recommended that intervention programmes to promote nutritional health should aim to improve micronutrient status further without leading to obesity. The role of psychological strengths in preventing the adverse effects of urbanisation on health needs to be examined in more detail.

Influence of long-term intervention with dietary counseling, long-chain n-3 fatty acid supplements, or both on circulating markers of endothelial activation in men with long-standing hyperlipidemia

BACKGROUND

Dietary factors and very-long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) may influence the atherothrombotic process. Elevated concentrations of circulating cell adhesion molecules, thrombomodulin (TM), von Willebrand factor (vWF), and tissue-type plasminogen activator antigen (tPAag) are related to atherothrombotic cardiovascular disease.

OBJECTIVE

The randomized Diet and Omega-3 Intervention Trial (DOIT) targeted a comparison of the effect of 3-y dietary counseling, n-3 PUFA supplementation (2.4 g/d), or both on circulating markers of endothelial activation.

DESIGN

The study included 563 elderly men with long-standing hyperlipidemia. The men were randomly assigned by factorial design into 4 groups: control (no dietary counseling and placebo capsules), dietary counseling (and placebo capsules), n-3 PUFA supplementation (no dietary counseling), and dietary counseling and n-3 PUFA supplementation.

RESULTS

Serum concentrations of fatty acids reflected good compliance. Dietary counseling was followed by significantly reduced concentrations of soluble intercellular adhesion molecule 1 (sICAM-1; P < 0.001), sTM (P = 0.004), and tPAag (P < 0.001) than in subjects without dietary counseling. After n-3 PUFA supplementation, significantly reduced concentrations of sICAM-1 (P < 0.001) and sTM (P = 0.006) were observed when compared with subjects receiving placebo capsules. An increase in tPAag was not significantly different from that observed in subjects receiving placebo capsules. For sICAM-1, a significant effect was observed for both interventions combined.

CONCLUSIONS

Each intervention (dietary counseling or n-3 PUFA supplements) reduced sTM and sICAM-1 concentrations, indicating decreased endothelial activation. The tPAag increase in the groups not receiving dietary counseling (pooled), which indicates progression of atherosclerosis, was significantly counteracted by dietary counseling.

The effect of vegetarian diet, plant foods, and phytochemicals on hemostasis and thrombosis

Ischemic heart disease (IHD) is multifactorial with a complex etiology. Conventional risk factors including serum lipids account for less than one half of future IHD events. In the past few years, novel risk factors such as hemostatic and thrombotic factors contributing to the development and progression of IHD have been explored. Typically, diet is the first line of consideration in the prevention of IHD, but very little is known about the effect of diet and nutrients on hemostasis and thrombosis. Cross-sectional studies indicate that vegetarians may have a lower concentration of certain markers of hemostasis compared with nonvegetarians. Platelet aggregation, an index of thrombosis, appears to be higher among vegetarians than nonvegetarians, perhaps because of the lower intake of long-chain n-3 fatty acids among vegetarians. Monounsaturated-fat-rich plant foods may have a protective role in hemostasis and may explain in part the lower incidence of IHD in Mediterranean countries where residents consume a diet high in monounsaturated fatty acid. Finally, certain fruits and vegetables such as soy, garlic, and purple grapes may have antithrombotic effects, which may in part be due to the phytochemicals in these foods. Although this review suggests that a plant-based diet with sufficient n-3 fatty acids and certain fruits and vegetables may have a favorable impact on hemostasis and thrombosis, the evidence is neither sufficient nor conclusive at this time to warrant specific recommendations for the public. Clearly, much remains to be done in this area of investigation.

Effect of genetic background and diet on plasma fibrinogen in mice. Possible relation with susceptibility to atherosclerosis

Many epidemiological studies suggest that elevated plasma fibrinogen concentrations form one of the most important independent risk factors in blood for cardiovascular disease and particularly atherosclerosis in humans. To clarify the effect of genetic factors, diets and their interactions on plasma fibrinogen concentrations, we examined plasma fibrinogen levels in four strains of mice, which differ in their susceptibility to cholesterol-induced atherosclerosis. When maintained on basal diet, two strains 129/J and C3H/HeJ exhibited a significantly higher plasma fibrinogen concentration (2.1 and 1.9 mg/ml) than C57BL/6J and BALB/C strains (1.5 and 1.4 mg/ml). The strongest and most rapid (1 week) increase of plasma fibrinogen (by all semi-synthetic diets) is observed in C57BL/6J mice, which are known to be highly susceptible to diet-induced atherosclerosis. After a period of 8 weeks an increase in plasma fibrinogen of approximately 30-50% was observed in all strains on all semi-synthetic diets. Remarkably, no increase was observed in the fibrinogen Aalpha- Bbeta- and gamma-chain mRNA levels in the liver on the same diets. These mRNA levels were even decreased by approximately 20-50% in all strains on an extremely atherogenic diet. It was found that: genetic background determines the plasma fibrinogen levels on basal diet; plasma fibrinogen levels are altered by diet; the extent of these changes depends on the genetic background: surprisingly, this increase of fibrinogen in plasma is independent of transcription; the diet-induced increase of fibrinogen was very fast in the very highly atherosclerosis-susceptible strain C57BL/6J having a low basal fibrinogen level, and very slow in the atherosclerosis-resistant strain C3H/HeJ having a high basal fibrinogen level. It might be concluded that it is the kinetics of the response of fibrinogen to diet rather than the actual level, which relates to atherosclerosis susceptibility.

Nutritional status influences plasma fibrinogen concentration: evidence from the THUSA survey

Nutritional status and risk factors for chronic diseases, including plasma fibrinogen and its determinants, of Africans in the Northwest Province of South Africa, have been studied in a cross-sectional survey. A representative sample of 1854 "apparently healthy" African men and women volunteers aged 15 years and older was recruited from 37 randomly selected sites throughout the Province and stratified for level of urbanisation. Information was collected using validated and culture-sensitive questionnaires. Fasting blood samples were drawn, and all measurements were done with standardised methodology using appropriate equipment, procedures, and controls. Fibrinogen concentration was measured in citrated plasma with the method of Clauss, using the ACL200 automated system and the international fibrinogen standard. The results revealed a population with a high mean plasma fibrinogen (3.17+/-1.10 g/L for HIV-negative men and 3. 64+/-1.12 g/L for HIV-negative women). Factors known to influence plasma fibrinogen, such as age, gender, smoking habit, and physical activity, were also observed in this population. Young rural men and women had the lowest fibrinogen level. Nasal snuff taking and HIV infection did not influence fibrinogen concentration. Multivariate analyses revealed that lower plasma fibrinogen was associated with low to normal body mass index in women, and with dietary intakes compatible with prudent dietary guidelines in men and women (low intakes of animal protein; trans fatty acids and higher intakes of plant protein; dietary fibre, vitamin E, and iron, and a high dietary P/S ratio). Subjects in the higher quartiles of plasma fibrinogen had significantly lower iron, vitamin E, and vitamin B6 (women) status. Increases in fibrinogen were associated with significant increases in serum lipids. Both under- and overnutrition seem to be associated with high plasma fibrinogen. It is concluded that overall nutritional status, possibly in addition to specific nutrients (and foods), influences plasma fibrinogen.

The influence of a vegetarian diet on haemostatic risk factors for cardiovascular disease in Africans

Dietary habits have been implicated in the occurrence of cardiovascular diseases. Elevated plasma fibrinogen levels and decreased fibrinolytic activity have been identified as major independent cardiovascular risk factors. In this study, we compared the blood pressure, plasma fibrinogen concentration, and fibrinolytic activity of 40 nonvegetarians (NON-VEGs) with 36 vegetarians (8 VEGs and 28 SEMI-VEGs). The latter group consisted of students and lecturers of the Adventist Seminary Institute of West Africa, Ilishan Remo. All subjects had blood pressures below 140/90 mmHg, no underlying haemostatic disorders and were not on any medical treatment. The NON-VEGs had significantly decreased fibrinolytic activity (p<0.001) and increased plasma fibrinogen levels (p<0.001) compared with the SEMI-VEGs and VEGs. There were no significant differences between the blood pressure levels of the three groups, although the NON-VEGs had lower diastolic blood pressures. It is concluded that black African Seventh-Day Adventists who follow a vegetarian diet may be protected against premature cardiovascular disease because of beneficial dietary effects on plasma fibrinogen levels and fibrinolytic activity.