Amira N. Kassis

Policosanols as nutraceuticals: fact or fiction.

Policosanols (PC) are very long chain aliphatic alcohols derived from the wax constituent of plants. In the early 1990s, researchers at Dalmer Laboratories in La Habana Cuba isolated and produced the first PC supplement from sugarcane wax. The original PC supplement has been approved as a cholesterol-lowering drug in over 25 countries throughout the Caribbean and South America. Cuban studies claim that 1 to 20 mg/day of the original PC supplement are effective at producing significant reductions in total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C). These studies also show that PC supplements are potent antioxidants, promote proper arterial endothelial cell function, inhibit platelet aggregation and thrombosis, and serve as effective treatments for intermittent claudication. However, for the most part, those studies reporting therapeutic efficacy of PC were carried out by one research group situated in Cuba. Conversely, research groups outside of Cuba have failed to validate the cholesterol-lowering and antioxidant efficacy of PC. Cuban researchers, however, continue to claim that the efficacy is attributed to the unique purity and composition of the original PC preparation, a mixture not found in PC products used by external research groups. The absence of independent and external studies confirming the therapeutic benefits of PC in disease prevention and treatment raises questions regarding their true efficacy.

Glycemic Responses and Sensory Characteristics of Whole Yellow Pea Flour Added to Novel Functional Foods

A fundamental understanding regarding postprandial glycemic responses to foods containing whole yellow-pea flour (WYPF) remains unknown. This, alongside concerns that WYPF possesses unfavorable sensory characteristics has limited the incorporation of WYPF into new functional food products as a healthy novel ingredient. The objective of this study was to evaluate how WYPF modulates postprandial glycemic responses as well as sensory characteristics in novel foods. In a single-blind crossover trial, the present study assessed postprandial glycemic responses of banana bread, biscotti, and spaghetti containing either WYPF or whole wheat flour (WWF). Boiled yellow peas (BYP) and white bread (WB) were used as positive and negative controls, respectively. On day 1, subjects evaluated appearance, taste, texture, smell as well as overall acceptance of each WYPF and WWF food on a 5-point hedonic scale. WYPF banana bread (97.9 +/- 17.8 mmol x min/L) and biscotti (83 +/- 13 mmol x min/L), as well as BYP (112.3 +/- 19.9 mmol x min/L), reduced (P < 0.05) glycemic responses compared to WB (218.1 +/- 29.5 mmol x min/L). The glycemic response of WYPF pasta (160.7 +/- 19.4 mmol x min/L) was comparable to WB. WYPF biscotti produced a lower (P = 0.019) postprandial glycemic response compared to WWF biscotti (117.2 +/- 13.1 mmol x min/L). Hedonic responses between corresponding foods were similar except for the WYPF pasta (2.9 +/- 0.9) which possessed a lower sensory score (P = 0.02) for smell compared to WWF pasta (3.6 +/- 1). WYPF can be used to produce low-glycemic functional foods possessing sensory attributes that are comparable to identical food products containing WWF.

Efficacy of plant sterols is not influenced by dietary cholesterol intake in hypercholesterolemic individuals

Plant sterols (PSs) reduce plasma total and low-density lipoprotein cholesterol (LDL-C) levels by reducing cholesterol absorption; however, it is not known whether the level of dietary cholesterol intake has an impact on the efficacy of PSs on blood lipids. The purpose of this study was to determine the effect of high vs low dietary cholesterol levels on the lipid-lowering efficacy of free PSs. The study was a semirandomized, double-blind, crossover trial consisting of four 28-day feeding phases each separated by a 4-week washout period. Otherwise healthy hypercholesterolemic subjects (n = 22) consumed each of (a) low-cholesterol control (C(-)S(-)), (b) high-cholesterol control (C(+)S(-)), (c) 22 mg PSs per kilogram of body weight with a low-cholesterol diet (C(-)S(+)), and (d) 22 mg PSs per kilogram of body weight with a high-cholesterol diet (C(+)S(+)). Blood was drawn on the first and last 2 days of each phase to measure plasma total cholesterol, LDL-C, high-density lipoprotein cholesterol, and triacylglycerols as well as plasma campesterol and beta-sitosterol concentrations. Dietary cholesterol had no effect on PS efficacy as a cholesterol-lowering agent because no interaction was found between the 2 factors. However, dietary cholesterol and PS intake had significant independent effects on plasma total cholesterol, LDL-C, and high-density lipoprotein cholesterol levels. beta-Sitosterol levels in plasma increased (P < .0001) as a result of PS supplementation. Data from the present study indicate that, although PSs and dietary cholesterol exert independent effects on plasma cholesterol, PS efficacy is not affected by varying levels of cholesterol intake.

Comparison of composition and absorption of sugarcane policosanols

Policosanols (PC) exist as very-long-chain alcohols derived from sugarcane currently used in many countries as a cholesterol-lowering therapy. PC purity and relative percentage composition have been suggested as primary reasons why the original Cuban PC (OPC) supplements possess lipid-lowering efficacy. The purpose of the present study was, first, to compare the relative percentage purity and PC composition of both OPC and alternative sources of PC (APC). A second objective was to feed Syrian hamsters a diet containing 0.275 mg PC/g of either the OPC or an APC product (APC1) and compare subsequent tissue, plasma and faecal PC levels. Five animals from the APC1 dietary group received a diet containing ten times the original amount of PC. Results indicate that the APC formulations have a composition that is highly consistent with the OPC supplement, with octacosanol being present within the cited 60-70 % range. PC were undetectable in the small intestine, liver, adipose or plasma in animals fed either source. Hamsters fed OPC excreted octacosanol (C28) more rapidly (P < 0.05) than hamsters receiving APC1. If the cholesterol-lowering efficacy of PC mixtures is dependent on their purity and composition, then sugarcane-derived APC products should possess similar therapeutic properties as the OPC supplement.

Changes in cholesterol kinetics following sugar cane policosanol supplementation: a randomized control trial

BackgroundSugar cane policosanols (SCP) have been shown to exert cholesterol-modulating properties in various studies conducted in Cuba by substantially reducing cholesterol synthesis. Independent research examining changes in cholesterol kinetics in response to SCP is limited to few studies, none of which was able to replicate findings of the original research. Moreover, no data are available on the effect of SCP on cholesterol absorption to date. The present study was undertaken to determine effects on cholesterol kinetics, namely synthesis and absorption, within hypercholesterolemic individuals consuming a SCP treatment. Twenty-one otherwise healthy hypercholesterolemic subjects participated in a randomized double-blind crossover study where they received 10 mg/day of policosanols or a placebo incorporated in margarine as an evening snack for a period of 28 days. The last week of the study phase, subjects were given 13C labelled cholesterol and deuterated water for the measurement of cholesterol absorption and synthesis respectively. Blood was collected on the first two and last five days of the trial. Cholesterol absorption and synthesis were determined by measuring red cell cholesterol 13C and deuterium enrichment, respectively.ResultsThere was no significant change in LDL cholesterol levels as compared to control. In addition, the area under the curve for red cell cholesterol 13C enrichment across 96 hours was not significantly different in the SCP group as compared to control. Similarly, no difference was observed in the fractional rate of cholesterol synthesis over the period of 24 hours between the two treatment groups.ConclusionThe findings of the present study fail to support previous research concerning efficacy and mechanism of action for policosanols.

Reply to the discussion by Sergei V. Jargin on Evaluation of cholesterol-lowering and antioxidant properties of sugar cane policosanols in hamsters and humansAppears in Appl. Physiol. Nutr. Metab. 34: this issue.

Policosanols were shown to have positive effects on cholesterol levels in more than 30 clinical studies originating from Cuba. The policosanol controversy revolves around the fact that these studies were conducted by one single jurisdiction using one single mixture. Based on thorough searches for full text manuscripts in the policosanol literature, no independent studies using the original policosanol mixture was able to replicate the cholesterol efficacy seen in Cuban studies. The two clinical trials cited by Dr. Jargin (Nikitin et al. 2000; Prat et al. 1999) do indeed add to the positive body of evidence provided by Cuban researchers. However, these studies were not included in the aforementioned thesis due to the inaccessibility of corresponding full texts and our lack of resources to translate the manuscripts from Russian and Spanish to English. In fact, these studies are not available in English and are therefore only accessible to a restricted audience. Furthermore, the limited details on study designs included in the abstract clearly show that although sample size and randomization were appropriate, the lack of placebo in the trials (often noted as a limitation of Cuban studies as well) weaken the con