Genes and lipid nutrition of Mongoloid are different from those of Caucasoid. Westernization of Mongoloids resulted in increase of diseases related to lipid metabolism including diabetes and atherosclerosis. The Mongoloid-specific genetic factor is mainly composed of single nucleotide polymorphism (SNP). Those SNPs saving energy and induce diabetes are called "thrifty SNPs", and include b-adrenergic receptor (b3AR), uncoupling proteins (UCPs)1 and 2, and UCP promoter (UCP3p), PPAR-g2, leptin receptor (LEPR) etc. These SNPs constitute obesity-prone genetic factors of Mongoloids under Westernized dietary habits. We studied these SNPs in Mongoloid living in Japan, Okinawa, Palau, Thai, China, Tonga and Mongol (Biochem. Biophys. Res. Commun. 295: 207-222, 2002). We also analyzed SNPs of the patients in our Nutrition Clinic, who were educated 25-31 years before. Despite differences in these SNPs, the special dietary habits (four-group point method) and exercise prevented most of the lifestyle related diseases.
During the past two decade, the nutrition situation of Vietnam is changing rapidly. According to the national nutrition survey in 2000, the daily average intake of animal products specially meat is increasing clearly (meat intake from 24g in 1990 to 51g in 2000). The proportion of diet energy is changed, the part of fat energy have raised from 6 per cent (1990) to 12 per cent (2000) and in many urban groups-more than 20 per cent. The use of oil is common in urban areas while in rural areas pork fat is more popular. Though the improvement is still modest but new emerging health problems has appeared. While PEM (underweight, stunting), micronutrient deficiencies are still of public health significance, the rate of overweight, obesity (primary school children, adult in urban areas), hypertension and diabetes is increasing alarmingly. The rate of type 2 diabetes in 4 big cities is raising from 1-2 per cent in the beginning of 1990 decade up to 4, 9 per cent actually. The majority of obese subjects have abdominal obesity and the percentage of body fat is relative high. Studies on lipid status have shown that the prevalence of high serum cholesterol was the lowest in the rural (2%) and the highest in the urban (16%) and in contrary the low serum cholesterol percentage was the highest in the rural (45, 3%) and the lowest in the urban (11, 2%). The high index of thrombogenecity (IT) of the Vietnamese diet may result from their low intake from fish and vegetable oil.
Cholesterol is an important component of all eukaryotic plasma membranes. It is also the precursor of steroid hormones such as progesterone, testosterone, estradiol, and cortisol. Cholesterol is synthesized from acetyl CoA (acetate) in the liver, small intestine, arterial wall, etc. The amount of cholesterol in the cell is well-balanced by de novo biosynthesis, uptake by the cell via the LDL receptor and extracellular excretion. It is well known that lifestyle-related diseases, including heart diseases, are caused by disorders of such regulation. Therefore, it is very important to understand the mechanism of cholesterol for the maintenance of a healthy life. This paper reviews the: (1) structure and character of cholesterol, (2) role of cholesterol, (3) biosynthesis, transport and excretion of cholesterol, (4) cholesterol homeostasis and (5) serum cholesterol and atherosclerosis.
Effects of polyphenols including anthocynins, which are distributed in many food products, on serum lipid levels were investigated in relation with their chemical structures in rats. Astibin and its aglycone, taxifolin which are major components in Koki-cha (processed from leaves of Engelhardita chrysolepis), amperopsin which is a major flavonoid in To-cha (processed form the stems and leaves of Ampelopsis grossedentata), Ruburobrassicin (an anthocyanin contained in red turnips), Nasunin (a major anthocyanin in eggplants), and quercetin showed suppressing effects on elevating serum cholesterol levels and on the atherogenic index in the rats fed a cholesterol-enriched diet. Astilbin and taxifolin with a dihydroflavanol structure showed slightly stronger effects on cholesterol-lowering effects in comparion with flavonol such as quercetin. As the cholesterol-lowering effects of isorhamnetin and rhamnetin were almost equal with qurcetin, it was suggested that the substitution of the hydroxyl group at 31 or 7 position of querecetin with the methoxyl group did not affect the serum cholesterol level. An increase in fecal excretion of bile acids in rats fed these polyphenols suggested that polyphenols increase fecal excretion of bile acids which is a factor in decreasing serum cholesterol level and the atherogenic index in the rats fed a cholesterol-enriched diet.
Setting the adequate levels of serum cholesterol is controvertial. Recent basic researches demonstrated the event of atherosclerosis formation: that is, lipid storage making lipid pool, smooth muscle cell proliferation leading to intimal thickninng, inflammatory cell invasion leading to fragility of the matrix, cell apoptosis leading to disappearance of the cell, and plaque rupture. In these process, the chronic inflammatory reaction is insidiously continuing. The most important factor for promoting the inflammatory reaction might be oxysterols, because we found that oxysterols are generated in advanced atherosclerotic lesion, and are very toxic. And, oxidative stress promoted the production of oxysterols. Then, we propose that the atherogenicity is serum cholesterol level times oxidation stress. The latter index was calculated from measuring urinary excretion of 8 hydroxy deoxyguanine. Considering those, total cholesterol level which did not affect to make the progression of atherosclerosis is 140 mg/dl. Oxidative stress in metabolic syndrome was 1.6 times than control. Then, 140×1.6=220 mg/dl might be lower limit involving atheroma formation in standard oxidative stress. If antioxidative stress might be equipped, the limit might be raised. Precise evaluation of oxidative stress might be required.
The health risk from hypercholesterolemia in Japan has been overemphasized for years. When discussing the risk of hypercholesterolemia, the famous figure is often cited that shows an exponential relationship between serum cholesterol levels and the risk of coronary heart disease (Guideline for Diagnosis and Treatment of Hyperlipidemias in Adults, 1997, Japan Atherosclerosis Society). This figure, consisting of several sets of epidemiological data, recently turned out to be based on unreliable data and data manipulation. One of the misleading epidemiological studies in that figure incorporated a surprisingly large number of familial hypercholesterolemic subjects. Familial hypercholesterolemia should be excluded from this kind of epidemiological studies, because the disease is rare (0.2%), and the incidence of coronary heart disease is exceptionally high. Almost all the recently performed large-scale epidemiological studies in Japan showed that higher cholesterol levels, like 240-260 mg/dL (6.2-6.7 mmol/L) or 240-280 mg/dL (6.2-7.3 mmol/L), are safer than lower cholesterol levels in terms of all-cause mortality. This is partly due to a very low coronary heart disease incidence in Japan. Prescribing lipid-lowering medicines to subjects with 240 to 260 mg/dL of cholesterol, which is recommended by the newest guideline (2004) of Japan Atherosclerosis Society, faces the paradox of treating those who are least likely to die. The guideline for hypercholesterolemia must be set by those researchers who have not received any assistance from cholesterol-lowering drugs makers.
Metabolomics is a relatively new discipline and techniques for high-throughput metabolic profiling and still under development. No single technique is suitable for the analysis of all different types of molecules, so a mixture of techniques is used. Methods such as gas. chromatography-mass spectrometry, capillary electrophoresis-mass spectrometry, liquid chromatography-mass spectrometry and Fourier transform-ion cyclotron resonance-mass spectrometry are used to separate metabolites according to various chemical and physical properties. After analysis of data obtained from mass spectrometry, bioinformatic databases are required to identify metabolites. In lipidomics, several databases are developed for this purpose, such as Lipid Search, LIPID BANK for Web, Atomic Reconstruction of Metabolism (ARM). Lipid Search is a database for identification of lipid compounds, LIPID BANK for Web is lipid encyclopedia, and ARM is software for drawing metabolic map. In near future, these databases will be linked each other and contribute to further development of lipidomics.
N-3 polyunsaturated fatty acids and green tea extracts are effective for the prevention of life style related disease. Japanese people have consumed the large amounts of fish and green tea. We have clarified the properties of sardine, catfish, and sea snake lipids. The lipid content of sardines was high from July to September, and the characteristics of the fatty acids isolated from sardines in those period were similar to those from plankton in the same season. Japanese catfish and sea snake lipids showed lower n-3 polyunsaturated fatty acid percentages comparing with general fish oil. However, intake of Japanese catfish lipids decreased the liver total cholesterol as well as the sardine lipid intake. Furthermore the sea snake lipids have stronger lowering-effects on plasma lipids and glucose concentrations than a fish oil mixture containing the same percentage of 22:6n-3. The stimulations intake of fish oil and green tea components were effective for the lowering plasma lipid. Japanese model fat diet lowered the plasma glucose, and green tea extraction intake effectively promotes the influence. The stimulations intake of DHA and catechin showed improved-effects on the brain function. The stimulations intake of fish and green tea are may be effective for the human health.
Correlations between serum fatty acid composition (weight%) and leptin, BMI, triglyceride (TG), total cholesterol (TC), HDL cholesterol (HDLc), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were analyzed in sixty one male (41-80 years old) and twenty three female (52-79 years old) subjects without cardiovascular disease or diabetes meritus. Statistically significant negative correlations were found between nervonic acid (C24:1:n-9) and leptin, BMI and TG. Significant positive correlations were found between lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), γ-linolenic acid (C18:3:n-6) and total saturated fatty acids (Σ SF) in female. A significantly negative correlation between linoleic acid and systolic blood pressure, and significantly positive correlations between eicosapentaenoic acid (EPA, C20:5:n-3) or dexahexaenoic acid (DHA, C22:6:n-3) and systolic blood pressure were found in male subjects. In conclusion, serum nervonic acid could be a predictor of leptin status, obesity and hypertriglyceridemia.