Comparison of the effects of diets rich in stearic acid versus myristic acid and lauric acid on platelet fatty acids and excretion of thromboxane A2 and PGI2 metabolites in healthy young men

Chronic and acute effects of cocoa products intake on arterial stiffness and platelet count and function: A systematic review and dose-response Meta-analysis of randomized clinical trials

The findings of trials investigating the effect of cocoa products consumption on vascular stiffness and platelet are controversial. The aim of this study is to summarize the findings on the acute and chronic effects of different forms of cocoa on the risk factors of cardiovascular disease. We searched SCOPUS, Pub Med and Web of Science from inception to Jan 2020. Finally, the random-effect model was used to report the pooled effect sizes. Results are expressed as weighted mean difference (WMD) with 95% confidence intervals (CI).Overall, 41 trials were included, of which only 14 studies met the eligibility criteria for analysis, including 11 long-term RCTs (more than a week was considered as a chronic phase) and 7 short-term RCTs (less than a week was considered as an acute phase). According to the result of 11 long-term RCTs, cocoa products had a negative significant effect on pulse wave velocity; PWV (WMD: -0.33 m/s, P < 0.0001), Augmentation index; AIx (WMD: -4.50%, P = 0.001) but had no significant effect on platelet count (WMD: -10.41 10⁹/L, P = 0.053). Also, according to the results of 7 short-term RCTs, cocoa products had a negative significant effect on PWV (WMD: -0.27 m/s, P = 0.019), AIx (WMD: -4.47%, P = 0.003).Current study indicated the beneficial effect of acute and chronic consumption of cocoa-based products ingestion on platelet function and arterial stiffness in healthy adult regardless of age especially in male and for consumption (≤4 weeks) in the chronic intake and (≤120 minutes) in acute intake, but did not affect on platelet count. However, further studies are required to shed light on this issue.

Effects of cocoa products/dark chocolate on serum lipids: a meta-analysis

Cocoa products, which are rich sources of flavonoids, have been shown to reduce blood pressure and the risk of cardiovascular disease. Dark chocolate contains saturated fat and is a source of dietary calories; consequently, it is important to determine whether consumption of dark chocolate adversely affects the blood lipid profile. The objective was to examine the effects of dark chocolate/cocoa product consumption on the lipid profile using published trials. A detailed literature search was conducted via MEDLINE (from 1966 to May 2010), CENTRAL and ClinicalTrials.gov for randomized controlled clinical trials assessing the effects of flavanol-rich cocoa products or dark chocolate on lipid profile. The primary effect measure was the difference in means of the final measurements between the intervention and control groups. In all, 10 clinical trials consisting of 320 participants were included in the analysis. Treatment duration ranged from 2 to 12 weeks. Intervention with dark chocolate/cocoa products significantly reduced serum low-density lipoprotein (LDL) and total cholesterol (TC) levels (differences in means (95% CI) were -5.90 mg/dl (-10.47, -1.32 mg/dl) and -6.23 mg/dl (-11.60, -0.85 mg/dl), respectively). No statistically significant effects were observed for high-density lipoprotein (HDL) (difference in means (95% CI): -0.76 mg/dl (-3.02 to 1.51 mg/dl)) and triglyceride (TG) (-5.06 mg/dl (-13.45 to 3.32 mg/dl)). These data are consistent with beneficial effects of dark chocolate/cocoa products on total and LDL cholesterol and no major effects on HDL and TG in short-term intervention trials.

Fatty acids and atherosclerotic risk

Most research concerning the effects of dietary fatty acids on atherosclerotic risk has focused on their effects on lipid and lipoprotein metabolism. However, it is known that fatty acids also influence a number of other relevant mechanisms involved in atherosclerosis such as lipid peroxidation, inflammation and haemostasis. The most favourable distribution of cholesterol over the various lipoproteins is achieved when saturated and trans fatty acids are replaced by a mixture of cis-unsaturated fatty acids. Furthermore, fatty acids from fish oil lower triacylglycerol concentrations. Effects on other atherosclerotic risk markers are less evident. Monounsaturated fatty acids maybe preferable above other fatty acids with respect to low-density lipoprotein oxidation as measured by indirect in vitro assays. The relevance of these assays for the in vivo situation is, however, limited. With respect to inflammation, mainly the effects of n-3 polyunsaturated fatty acids from fish oil have been studied, but results were inconsistent. Also results from studies evaluating the effects of fatty acids on haemostatic risk markers were inconsistent, which may be partly related to the use of different analytical methods. The most consistent finding however is the potential beneficial effect of moderate intakes of fish oil on platelet aggregation. Furthermore, reducing total fat intake rather than changing the fatty acid composition of the diet may beneficially affect the coagulation system. In conclusion, while beneficial effects on atherosclerotic risk are mainly ascribed to cis-unsaturated fatty acids, it remains debateable whether trans and saturated fatty acids in the diet have to be replaced by cis-unsaturated fatty acids or by carbohydrates. To answer this question adequately more validated methods are needed that reflect in vivo lipid peroxidation, inflammation and haemostasis.

Short-term diets enriched in stearic or palmitic acids do not alter plasma lipids, platelet aggregation or platelet activation status

OBJECTIVE

To determine whether healthy males who consumed increased amounts of dietary stearic acid compared with increased dietary palmitic acid through the consumption of commercially available foods, exhibited any changes in plasma lipids, platelet aggregation or platelet activation status.

DESIGN

A randomised cross-over dietary intervention.

SUBJECTS AND INTERVENTIONS

Nine free-living healthy males consumed two experimental diets (stearic acid enriched, diet S, and palmitic acid enriched, diet P) for 3 weeks in a randomised cross-over design separated by a 3 week washout phase. The diets consisted of approximately 30% of energy as fat (30% of which was derived from the treatment diets) providing approximately 13 g/day as stearic acid and 17 g/day as palmitic acid on diet S and approximately 7 g/day as stearic acid and 22 g/day as palmitic acid on diet P. The dietary ratio of stearic to palmitic acids was 0.76 on diet S compared with 0.31 on diet P. Blood samples were collected on days 0 and 21 of each dietary period.

RESULTS

LDL cholesterol levels and platelet aggregation response to the agonist ADP were significantly decreased (P<0.025) in subjects on diet S compared with day 0. Apart from that, there were no significant changes in plasma lipids, platelet aggregation, mean platelet volume and platelet reactivity between diets. There were no significant changes in stearic or palmitic acid levels in plasma phospholipid or triacylglycerol. There was a significant difference in palmitic acid levels in platelet phospholipids between the two diets.

CONCLUSIONS

Use of commonly available foods led to a 27% increase in stearic acid (diet S) and a 19% increase in palmitic acid (diet P), on diets S and P respectively, and no significant differences between the two diets in plasma lipoprotein concentrations, platelet aggregation or platelet activation status.

Similar effects of diets rich in stearic acid or trans-fatty acids on platelet function and endothelial prostacyclin production in humans

The effects of stearic acid (C18:0) and trans-fatty acids (trans-FAs) on measures of platelet function and prostacyclin (PGI2) production are poorly understood in humans. In this controlled dietary study, platelet function and endothelial PGI2 production were studied in healthy humans after they consumed diets rich in C18:0 or trans-FAs. For 5 weeks, 80 subjects consumed a baseline diet high in saturated FAs and were then switched to a diet containing 9.3% of energy as stearic acid or a diet containing 8.7 energy% as trans-FAs from hydrogenated vegetable oils for another 5 weeks. All diets contained 32.2 to 33.9 energy% fat, 14.6 to 15.8 energy% saturated plus trans-FAs, 12.2 to 12.5 energy% cis-monounsaturated, and 2.9 to 3.5 energy% polyunsaturated FAs. No significant differences between the C18:0 and trans-FA diets were found in the urinary excretion of 2,3-dinor-thromboxane B2 or 2,3-dinor-6-keto-prostaglandin F1alpha. In vitro production of thromboxane B2 by platelets as well as urinary excretion of beta-thromboglobulin were also similar after both diets. Collagen-induced in vitro aggregation was significantly enhanced after the C18:0 diet compared with the trans-FA diet (P=.02), whereas no differences between the diets were found with ADP. The results indicate similar effects of C18:0 and trans-FA diets on platelet activation and endothelial PGI2 production.

Fatty acids and breast cancer cell proliferation

We and others have shown that fatty acids are important regulators of breast cancer cell proliferation. In particular individual fatty acids specifically alter EGF-induced cell proliferation in very different ways. This regulation is mediated by an EGFR/G-protein signaling pathway. Understanding the molecular mechanisms of how this signaling pathway functions and how fatty acids regulate it will provide important information on the cellular and molecular basis for the association of dietary fat and cancer. Furthermore these in vitro studies may explain data previously obtained from in vivo animal studies and identify "good" as well as "bad" fatty acids with respect to the development of cancer.

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

Abnormal haemostasis, and specifically a pre-thrombotic state characterized by hypercoagulability, increased platelet aggregation and impaired fibrinolysis, is associated with increased atheroma and thrombosis. The recent literature clearly indicates that diet may prevent or be used to treat some abnormal haemostatic states. There are reports on effects of energy intake and expenditure, alcohol consumption, intakes of total fat, different fatty acids, fish oil, NSP and vitamins on markers of coagulation, platelet function and fibrinolysis. Some of the confusion and controversy in this field has arisen because the wrong markers of haemostasis have been measured in dietary trials. Moreover, many of the studies have lacked good dietary control. It is suggested that more sensitive, functional markers of the balance between the different facets of the haemostatic system should be measured. It is also important to test hypotheses developed from known observations and to propose mechanisms of action of the various dietary factors, based on our improved understanding of the haemostatic system.

Seasonal variation in parameters related to coronary heart disease risk in young men

Seasonal variation in the plasma lipids and lipoproteins is reported in the literature. Whether this variation is the result of changes in diet or other factors has not been adequately addressed. We investigated the effects of a controlled diet on the seasonal variation in the levels of plasma lipids and apolipoproteins and also on the excretion of urine metabolites of TXA2 and PGI2 in healthy males. Two well-controlled diet studies were conducted to evaluate effects of dietary fatty acids on plasma lipids (Studies 1 and 2; n = 33) and eicosanoid excretion (Study 2 only; n = 15). Participants consumed whole-food test diets in a randomized, four-period crossover design during each 26-day experimental period. A non-intervention control group also participated in each study (Study 1, n = 12; Study 2, n = 11). Blood was collected monthly and analyzed for plasma lipids and apolipoproteins A-1 (Apo A-1) and B100 (Apo B). Twenty-four hour urine samples were collected monthly only in Study 2 and analyzed for TXB2 and 6-keto-PGF1 alpha by RIA. Seasonal fluctuations were observed in all subjects in plasma Apo A-1 (zenith = July, with 95% CI June-July; P < 0.05) and Apo B (zenith = October, 95% CI September-November, P < 0.05). Although there was no significant variation in plasma cholesterol levels, the increase in Apo B is consistent with an increase in LDL particle number during the fall/winter. Additionally, excretion of both eicosanoid metabolites and the ratio of 6-keto-PGF1 alpha/TXB2 was markedly elevated in July (95% CI June-July, P < 0.001). Three seasonal fluctuations were observed both in participants who consumed a highly-controlled experimental diet and in the non-intervention controls. Thus, these results suggest a diet-independent seasonal variation in parameters thought to be involved in coronary heart disease risk status. An understanding of these variations is important not oly for clinical evaluation and metabolic study design issues, but more importantly, to clarify their clinical significance with the seasonal incidence of CHD events.