Monday, July 12, 2010

Groundnut may cure diabetes, eye disease By Chukwuman Muanya

New researches suggest that eating a handful of groundnuts daily will not only prevent malnutrition, particularly the deficiency of niacin, but also check the development of diabetes, heart disease and age-related blindness.
THEY are in season. They are usually eaten boiled, roasted, put into a paste or oil. They are probably the most common snack in the country now.Groundnut or rather peanut is sold not just in the markets, but on the streets in most cities and even villages in Nigeria.Scientifically called Arachis hypogaea, the legume belongs to the pea and bean family, but it is considered as nut because of its high nutritional value. However, two new studies suggest that a meal of groundnut may be a better way of preventing degenerative diseases such as diabetes, heart disease and age-related blindness.Researchers have found that a naturally occurring chemical, resveratrol, found in groundnut (peanut), red wine, grapes and other plants may help reverse some of the ills associated with aging and being overweight such as diabetes and cardiovascular diseases.The findings are reported in the July issue of the American Journal of Pathology.What makes groundnut thick? Analysis of different nutrients in 100 grammes groundnut shows it contains 26 essential minerals and 13 different types of vitamins that include Vitamins A, B, C and E, which help in brain function and development and also to maintain strong bones.Phytochemical analysis per 100 gramme of groundnut indicates calcium - 93 milligramme (mg), carbohydrate - 16.13 gramme (gm), copper - 11.44 mg, fat - 49.24 gm, fibre - 8.5 gm, iron - 4.58 mg, magnesium - 168 mg, manganese - 1.934 mg, phosphorus - 376 mg, potassium - 705 mg, - 25.80 gm, sodium - 18 mg, water - 6.50 gm, and zinc - 3.27 mg.The chemical, resveratrol, has been shown to lengthen the life span of yeast and improve health in laboratory animals, but scientists do not yet know whether the substance might also benefit humans.The two new studies of older or overweight people suggest that resveratrol can, by helping boost the action of insulin, thus preventing diabetes.
And a study in mice shows that the chemical works through a previously unknown mechanism to halt harmful blood vessel growth in the retina.As people age or gain weight, their ability to respond to insulin declines. Some people become mildly resistant to insulin’s action, so that their muscles and other tissues no longer take up and burn glucose efficiently. That condition, known as insulin resistance, is one of the first steps toward diabetes. Now, researchers have found that resveratrol improves the response to insulin in overweight people with insulin resistance and older people with mild insulin resistance. The older people in the study were an average age of 72.Resveratrol has previously been shown to stimulate the activity of proteins known as sirtuins, which have been linked to longer life and better regulation of metabolism in laboratory animals. But a new animal study indicates that resveratrol may work through other biological processes to stop blood vessels from invading the retina and causing blindness associated with eye diseases such as macular degeneration, or retinopathies caused by diabetes or premature birth.Resveratrol inhibited blood vessel growth in the retinas of mice that had injuries to their eyes caused by lasers, a new study appearing in the July issue of the American Journal of Pathology shows. Resveratrol was able to stop blood vessel growth even when researchers inactivated the sirtuin proteins, indicating that the chemical’s effect on blood vessel growth must work by another mechanism.A Retinal Surgeon at Washington University School of Medicine in St. Louis, United States, who led the study, Prof. Rajendra Apte, said: “That mechanism turns out to be a biological process involving a protein known as elongation factor-2,” he says.Other researchers have suspected that resveratrol may do its work through more than just sirtuins, but the new study provides some of the first evidence that resveratrol may take multiple pathways toward improving health.Researchers have also demonstrated how diabetic rats fed with groundnut oil showed a small but significant reduction in Total Cholesterol (TC), Very Low Density Lipo-protein/ ‘very bad’ cholesterol (VLDL-C), Low Density Lipo-protein/ ‘bad’ cholesterol (LDL-C) and Triglycerides (TG) and an elevation in High Density Lipo-protein/ ‘good’ cholesterol (HDL-C). Groundnut oil consumption slightly but significantly decreases the blood glucose, glycosylated haemoglobin (HbA), lipid peroxidation and lipid profile and increases antioxidant levels in diabetic rats.Lipid peroxidation is the process whereby free radicals ‘steal’ electrons from the lipids in cell membranes, resulting in cell damage and increased production of free radicals or reactive oxygen species (causes cell damage).The study titled: “Effect of Dietary Substitution of Groundnut Oil on Blood Glucose, Lipid Profile, and Redox Status in Streptozotocin-diabetic Rats” was published in Yale Journal of Biology and Medicine by B. Ramesh, R. Saravanan and K.V. Pugalendi of the Department of Biochemistry, Faculty of Science, Annamalai University, Annamalainagar, Tamilnadu, India.The researchers wrote: “Groundnut oil-fed diabetic rats showed a significant elevation of Vitamin E in the plasma of diabetic rats. The increased level might be due to the presence of Vitamin E in the oil.“The levels of serum lipids are usually elevated in diabetes mellitus and such an elevation represents a risk factor for coronary heart disease. Diabetic rats fed with groundnut oil showed a small but significant reduction in levels of TC, VLDL-C, LDL-C, and TG and elevation in HDL-C levels when compared with diabetic controls. This could be due to the presence of Mono Unsaturated Fatty Acid (MUFA) and Poly Unsaturated Fatty Acid (PUFA) in the oil. “There have been numerous studies in humans and animals that have demonstrated that oils containing saturated fatty acids raise serum TC, TG and in particular, LDL-C levels, while those enriched in unsaturated fatty acids lower TC, TG and LDL-C. Diets high in monounsaturated fatty acids have been found to be relatively hypocholesterolemic (low cholesterol) or hypotriacylglycerolemic (low triglyceride).“In conclusion, our results show that groundnut oil substitution in the diet influences blood glucose, lipid profile, lipid peroxidation and antioxidants beneficially in Streptozotocin (STZ)-induced diabetic rats.

”Groundnut has also been employed in fighting malnutrition through micronutrient fortification of staple foods. In a major attempt to solve the problem of malnutrition, particularly micronutrients deficiency, the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) has recently launched a research to enhance the production of beta-carotenes (Vitamin A) in groundnut and help fight Vitamin A deficiency among resource poor consumers in the semi-arid tropics. ICRISAT is a non-profit international research organisation headquartered in India, devoted to science-based agricultural development.According to ICRISAT, in terms of nutrient value, groundnut contains high amounts of protein (25-30 per cent) and oil (46-50 per cent). Pound for pound, it contains more protein than meat, about two and half times more than eggs and far more than any other vegetable food, except soybean and yeast.Through bio-fortification, the nutritive content of peanut is levelled to a higher level—one that is rich in beta-carotenes. Groundnut, while being oil-rich and packed with other nutrients like zinc and iron, but deficient in beta-carotenes, it can be enhanced through the use of recombinant technologies as what has been done recently for rice (Golden Rice). Moreover, according to the scientist of ICRISAT, enrichment of human diets with beta-carotenes can facilitate the uptake of other important minerals like iron.While Vitamin A is only present in animal products, its predecessor beta-carotene or provitamin A can be found in several plant species. However, these are not taken up easily from digested food, because they are fat-soluble and their bioavailability depends on the presence of fat or oil in the same meal, failing which they are excreted undigested.
Oral delivery of Vitamin A is problematic, mainly because of the lack of infrastructure thus the need for viable alternatives. And this is where the ever-reliable groundnut comes in.Several groups of researchers in England have reported using groundnuts or its products in the treatment of haemophilia, an inherited blood disease, which causes haemorrhage. Beneficial results have also been reported from the use of groundnuts in severe cases of epistaxis or nose bleeding and in cases of excessive bleeding during menstruation in women.Groundnuts are considered beneficial in the treatment of obesity. Experiments have shown that body weight could be reduced by eating a handful of roasted groundnuts with tea or coffee without sugar an hour before lunchtime. It reduces appetite and thus reduces the weight gradually.However, some researchers suggest that excessive use of groundnuts causes high acidity in the body, spermetorrhoea and premature ejaculation. Groundnuts contaminated with aflatoxins (toxin produced by the fungus Aspergilus flavus) have also been linked with liver damage and cancer.Several studies indicate that some persons are allergic to roasted groundnuts. Asthmatics in particular are advised to abstain from eating groundnuts in excess. Some studies even suggest that pregnant women who eat a lot of groundnut increase the chance of their baby developing asthma.It is believed that groundnuts that are boiled in salted water are less harmful for such persons, however, liberal use of groundnuts should also be avoided by persons with gastritis and jaundice as their excessive use causes hyperacidity of the stomach, indigestion and heart burn.

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