Nutrition. 2015 Jan;31(1):180-6. doi: 10.1016/j.nut.2014.07.015.
Study of the effects of a diet supplemented with active components on lipid and glycaemic profiles
Ciro Langellaa, Daniele Navigliob, Marina Marinoc and Monica Galloa
aDepartment of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, via Pansini, 5; 80131 Naples, Italy
bDepartment of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Naples, Italy
cDepartment of Economic and Statistical Sciences, University of Naples Federico II, Via Cintia, 26, 80126 Naples, Italy
Objectives: Currently, there are numerous studies on risk factors for cardiovascular disease and the potential for functional foods to bring beneﬁts or improve people’s health. However, most of these studies are conducted with middle-aged individuals. The aim of this study was to evaluate the effects of supplementing a typical diet with some functional components, which are substances that when consumed in small quantities can improve people’s welfare. Methods: The participants in this study were young; slightly overweight; had normal glucose tolerance; and had lipid values indicating dyslipidemia or close dyslipidemia. Following a 4-wk run-in phase, participants followed either a diet containing foods enriched with omega-3 fatty acids, b-glucans, phytosterols, and vitamin E or an isoenergetic diet without the active components. Sixteen individuals (age range 20 to 37 y) were randomly assigned to one of two groups. At the end of treatment, while fasting, plasma concentrations of triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol were measured. Furthermore, blood glucose was evaluated after fasting and after a meal enriched with b-glucans. Results: There was a statistically signiﬁcant reduction (a < 0.05) across the lipid proﬁle. A meal rich in b-glucans produced a glycemic response signiﬁcantly lower than the nonenriched meal. Conclusion: The dietary supplements used in this work, based on the integration of functional components into the usual diet of the population, have proved effective in reducing peak levels of postprandial glucose and the risk for dyslipidemia. Therefore, these functional components proved a valuable aid in the prevention of cardiovascular diseases and metabolic disorders.
KEYWORDS: Active components; Cardiovascular diseases; Diet; Dyslipidemia; Metabolic disorders; Prevention
Epidemiological evidences documenting that the risk of cardiovascular events, correlated with high circulating levels of total cholesterol and especially LDL cholesterol, can be reduced by dietary intervention type or lifestyle able to control the lipoprotein profile (1). In particular, high intake levels of monounsaturated and polyunsaturated fats, reductions in saturated and trans fats, associated with the selective consumption of low-glycemic carbohydrates, fiber and vegetable protein, vitamins, phytosterols, in combination with an appropriate weight control and adequate physical activity are effective in the control of blood glucose, LDL cholesterol and HDL cholesterol. Therefore, dietary interventions aimed at improving eating habits and reduce body weight are key for preventing the onset of numerous diseases. Moreover, it is estimated that as many as 80% of cancer events is linked to diet, as well as the onset of cardiovascular disease is undoubtedly related to the type of feed. On the other hand, it is now increasingly documented the ability of functional components to provide a valid aid to this end. On this basis, the work published in 2015 evaluated the acute effects of dietary approaches on lipid and glycaemic profiles.
Dietary fat are important determinants of the lipid profile. The results of several controlled studies allowed to define the impact of different dietary fats on cholesterol levels linked to LDL and lipoprotein HDL.
A study conducted in the 70s on Inuit, the native population of Greenland, showed that although the diet of this population was very high in fat, they had a healthier heart and better health of other Europeans. Subsequent studies have shown that the fat in the diet of the Inuit came mainly from whales, seals, salmon and other marine animals, all rich in polyunsaturated fatty acids of the n-3 series (or omega 3).
The omega-3 fatty acids, both of vegetable origin like ALA (alpha linolenic acid), contained in nuts and some oils), that of marine origin EPA (eicoisapentenoic acid) and DHA (docosahexaenoic acid), present in high concentrations in fish especially of cold seas, modulate the plasma concentration of triglyceride-rich lipoproteins (VLDL), reducing the synthesis and the hepatic secretion (2).
Figure 1. Omega-3
Several studies have shown that omega-3 fatty acids help to reduce triglycerides and bad cholesterol (LDL), thus increasing the good one (HDL). They help prevent degenerative diseases, especially cardiac, protecting the walls of the blood vessels from the formation of atherosclerotic plaques. It also helps to decrease high blood pressure. Therefore, in the context of a balanced diet and a healthy lifestyle, the intake of omega-3 contributes to normal heart function.
Observational studies and systematic reviews of the literature have shown that a high intake of fiber in the diet is associated with a significant reduction in cardiovascular risk. Controlled clinical trials have confirmed the positive effects of the fiber on lipid profile and in particular on total cholesterol and LDL and triglycerides (3). This efficacy appears greatest for soluble fiber or gel forming (pectins, gums, beta-glucans, mucilages and the remaining hemicellulose), whose main food sources are some grains such as oats and barley (and derived products) and legumes. In particular, the intake of 5-10 g/day of soluble fibers such as the β-glucans, the glucomannan, guar and psyllium induces in particular a reduction of LDL cholesterol of about 5%.
Figure 2. Dietary fiber
Phytosterols, found in plant and, in smaller quantities oils, vegetables and fresh fruit, in the chestnuts, grains, legumes are structurally similar to cholesterol molecules. The absorption of phytosterols, in humans, is much lower than that of cholesterol (from 0.02 to 3.5% vs. 35-70%); despite their initial absorption is significant, they are in fact almost completely re-expelled in the intestinal lumen by the specific membrane transporters. Plasma levels of phytosterols in humans are therefore very low, about 1-2 mg/dl 45. Phytosterols interfere in the formation of the emulsion and micellar cholesterol transport himself with bile from the liver: the final effect of this interference is a reduction of absorption of cholesterol (both alimentary that biliary), and then blood cholesterol, especially LDL cholesterol (4). However, it is known that the plasma levels of β-carotene, for reasons still not entirely clarified, are reduced by 7-17% among individuals who regularly consume phytosterols, even after taking into account the reduction of LDL cholesterol, which is the physiological carrier in plasma of β-carotene and generally the lipophilic molecules. This reduction can be controlled by increasing the intake of fresh colorful vegetables. Beyond this reduction of β-carotene, the regular use of products enriched with phytosterols not appear to induce significant side effects.
Figure 3. Phytosterols
Vitamins are organic substances contained in foods, essential for the proper functioning of the body’s growth and maintenance. They have no energy or structural functions, but intervene with specific tasks in key reactions of metabolism. The vitamins are divided into water-soluble: the C, and the B complex, and liposoluble: E, D, K and A. The today’s diet is poor in vitamins, in fact, cooking, storage, refining reduce its content in foods.
In particular, vitamin E is a mixture of tocopherols, the most important is alpha-tocopherol. Many studies have shown the importance of this vitamin in increasing the antioxidant power of cells (5). Being fat soluble, it is absorbed and transported in the same manner followed by lipids. Its function is to act as an antioxidant, capable of protecting polyunsaturated fatty acids of biological membranes from damage caused by free radicals, which may alter the structure and functionality. Vitamin E is involved in the prevention of heart disease in various ways: lowers cholesterol levels, protects LDL from oxidation, prevents damage caused by free radicals while protecting cell membranes, reduces platelet aggregation and limits the adhesiveness of the white blood cells to the endothelium. In addition, vitamin E is essential for the immune system, particularly for T lymphocytes, and has a role in DNA repair.
Figure 4. Vitamins
In conclusion, it is quite clear that feeding in the complex must be regular, proper and healthy, as well as combined with regular exercise. Several literature data confirm that the possibility of preventing many diseases thus bringing considerable benefits on the health of the population require mediated integration of functional components in the diet. Therefore, depending on the results obtained in the study mentioned above, it can be said that the use of functional components aimed at prevention and treatment of dysmetabolic and cardiovascular diseases is fundamental and of unquestionable validity.
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