Natural supplements , more appropriately called “nutraceuticals”, are bioactive compounds present in some foods of plant or animal origin with possible beneficial effects on human health, if taken in concentrated doses higher than those present in the foods themselves. The main nutraceuticals with clinically proven cholesterol-lowering action, therefore able to control cholesterol , reducing its levels, are fibers , phytosterols , fermented red rice extracts and berberine . They are taken in drug-like formulations (tablets, capsules, sachets, gels).
The cholesterol-lowering effect of fibers
The cholesterol- lowering effect of natural supplements based on soluble fiber is attributed to its viscosity. By forming a gel that binds bile acids in the small intestine, the fiber increases their excretion with the faeces and leads to an increased use of cholesterol for the hepatic production of bile.
The cholesterol-lowering potential of the fiber is therefore proportional to its degree of viscosity. While an indirect action could also be carried out by the products of intestinal fermentation of the fiber, known as short-chain fatty acids, which can exert favorable effects on lipid metabolism .
In healthy subjects, in hypercholesterolemic patients and in those with diabetes mellitus, a modest but significant reduction in LDL cholesterol levels was observed , without significant side effects following dietary supplementation with oat β-glucan, psyllium, pectin , guar gum, chitosan, glucomannan and hydroxypropylmethylcellulose.
The effect of fiber on triglycerides and on the fraction of cholesterol linked to HDL is instead less clear, although some studies suggest a possible effect in reducing postprandial triglyceridemia. Excess fiber can cause gastrointestinal side effects.
Phytosterols for cholesterol control .
Phytosterolsand their esterified derivatives are bioactive components of vegetable origin which are found in small quantities in foods of vegetable origin such as fruit, vegetables, nuts, seeds, cereals, legumes and vegetable oils. They have a chemical structure similar to that of cholesterol so they compete with cholesterol in intestinal absorption mediated by the same carrier protein (NPC1L1), determining the cholesterol-lowering effect.
The phytosterols are then for the most part “ferried” back into the intestinal lumen and excreted with the faeces. Scientific evidence shows that the consumption of natural phytosterol supplementssignificantly reduces the concentrations of total cholesterol and the fraction linked to LDL by about 8-10% both in healthy subjects and in subjects with hypercholesterolemia. Although the use of phytosterols at the recommended doses (2 gr / day) does not cause significant side effects, their excessive consumption can be associated with a deficit in the absorption of fat-soluble vitamins.
Fermented red rice: the ally to combat cholesterol levels
The fermented red rice extract is a product of the fermentation of rice by a yeast, Monascus purpureus, which produces, among many others, a substance called monacolin K, structurally and functionally analogous to lovastatin, capable of inhibiting the enzyme HMGCoA reductase and therefore the synthesis of cholesterol.
Monacolin K could only be partially responsible for the cholesterol-lowering effect of the supplement based on fermented red rice extracts , as it contains at least 10 different more or less active monacolins in addition to β-sitosterol and campesterol capable of limiting the intestinal absorption of cholesterol, fiber, niacin, all substances with a cholesterol-lowering effect. The lipid-lowering efficacy of fermented red rice is confirmed by some meta-analyzes of randomized and controlled clinical trials.
Integration with fermented red ricehas been shown to be effective in reducing the risk of cardiovascular disease in adult and elderly patients in secondary prevention in a large study conducted in China of 1,445 patients (aged 65 to 75 years) with a history of myocardial infarction, randomized into two groups (placebo versus fermented red rice extract) and followed for an average of 4 years. The intake of the nutraceutical showed a reduction in the risk of CHD (-31.0%), mortality (-31.9%) and stroke (-44.1%). A natural food supplement based on fermented red rice useful for cholesterol control and Normolip 5 .
The fermented red rice extract is officially indicated amongdietary supplements with cholesterol-lowering activity from the European guidelines for the treatment of dyslipidemia with an efficacy of LDL cholesterol reduction of around 20-25%. The possibility of side effects similar to those of lovastatin should be considered, especially if the higher titrations of monacolin K. are used. Berberine
, cholesterol control and lipid metabolism
Berberineand a vegetable alkaloid present in various plants, such as Berberis vulgaris, Coptis chinensis, Berberis aristata. At the basis of the cholesterol-lowering effect of berberine, various mechanisms of action have been identified which have as a final result a regulation of gene expression of lipid metabolism regulatory genes capable of reducing plasma lipid levels .
The efficacy of berberine is demonstrated by randomized controlled clinical trials, even if carried out almost exclusively in the Asian population. Among the possible side effects of berberine, which emerged mostly in trials that used higher doses of the nutraceutical, are constipation, diarrhea, abdominal distension and a bitter taste in the mouth. An aspect that could affect the effectiveness of berberine, and its intestinal absorption often low and with a wide inter-individual variability.
