Effects of omega-3 fatty acids and vitamin E on hormones involved in carbohydrate and lipid metabolism in men

Article Abstract:

Fish oils have been widely studied for their ability to lower blood cholesterol levels. Fish oils contain large amounts of unsaturated fatty acids known as omega-3 fatty acids. These fatty acids have been shown to lower blood cholesterol levels in men with normal to high blood cholesterol levels, and to increase the amount of glucose (sugar) released from the liver into the blood. Previous studies have reported that omega-3 fatty acids can also alter the amount of insulin (a hormone that reduces blood sugar levels). Therefore, a study was performed to determine if omega-3 fatty acids, with and without added vitamin E, alter the levels of hormones in the blood that control fat and sugar metabolism. Forty healthy men followed a diet containing 15 grams of mixed fat/day for 10 weeks. During the second 10 weeks, 15 grams of fish oil (containing omega-3 fatty acids) was added to the daily diet, and during the final eight weeks vitamin E (200 milligrams/ day) was added. Blood samples were drawn during each diet period and analyzed for sugar, fat, insulin, glucagon (a hormone that increases blood sugar levels), and growth hormone (a hormone that decreases the amount of sugar and increases the amount of fatty acids in the blood). The fish oil diet increased the amount of sugar and decreased the amount of fat, insulin, glucagon and growth hormone in the blood, but did not alter cholesterol levels. Adding vitamin E to the fish oil diet caused a further reduction in insulin and growth hormone levels. It is concluded that fish oil and fish oil with added vitamin E alter the amount of sugar and fat in the blood by altering the levels of hormones that control sugar and fat metabolism. (Consumer Summary produced by Reliance Medical Information, Inc.)

Hormones, Blood sugar, Blood glucose, Lipid metabolism, Carbohydrate metabolism, Omega-3 fatty acids, Omega 3 fatty acids, Fish oils

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Serum 25-hydroxyvitamin D concentrations of free-living subjects consuming olestra

Article Abstract:

Dietary vitamin D is absorbed in the intestines in combination with dietary fats that are digestible. Dietary fats that are not digestible can reduce the absorption of vitamin D in the intestines. These findings have prompted investigations into the effects of indigestible fat substitutes on vitamin absorption. Olestra (previously called sucrose polyester) is a fat substitute that tastes like other dietary fats but cannot be digested, and thus does not add any calories to the diet. Previous studies have shown that eating a diet containing olestra does not reduce blood levels of vitamin D. However, the effect of olestra on the absorption of dietary vitamin D has not been determined. Therefore, a study was performed to determine the effect of olestra on vitamin D absorption. The study group consisted of 202 healthy adults who followed a six-week diet supplemented with cookies containing either 20 grams of olestra or 20 grams of triglycerides (fatty acids) per day. Both groups were given daily supplements of vitamin D in the form of ergocalciferol. Blood levels of 25-hydroxyergocalciferol (25-OHD2), 25-hydroxycholecalciferol (25-OHD3) and 25-hydroxyvitamin D (25-OHD) were measured before, during and after the test period. Daily vitamin D supplements, along with both the placebo and olestra diets, increased blood levels of 25-OHD and 25-OHD2 over the six-week test period. This increase was related to the dose of the vitamin D supplement, and was slightly greater for the placebo group than the olestra group. It is concluded that olestra, at a dose of 20 grams per day, does not cause vitamin D deficiency and does not compromise vitamin D nutritional status. (Consumer Summary produced by Reliance Medical Information, Inc.)

Vitamin D, Intestinal absorption, Fat substitutes, Olestra (Fat substitute)

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Dietary fat and menstrual-cycle effects on the erythrocyte ghost insulin receptor in premenopausal women

Article Abstract:

The metabolism of carbohydrates and fats (lipids) is regulated by hormones such as insulin. Insulin is secreted by the pancreas and facilitates the uptake of glucose by body cells. Diet can affect the blood levels of hormones such as insulin. A low-fat high-carbohydrate diet stimulates the pancreas to release more insulin than does a high-fat low-carbohydrate diet. On a more specific level, dietary fat can alter the receptors in cells that respond to insulin. Hormones communicate with body cells by way of structures called receptors. The authors investigated the influence of dietary fat on insulin receptors in 31 premenopausal women aged 20 to 40. The most important finding was that on a low-fat high-carbohydrate diet, the insulin receptors bound less insulin, leaving more insulin circulating in the bloodstream. Unlike some other studies, an inverse relationship was noted between the amount of insulin binding to receptors and levels of blood insulin; thus when insulin binding was higher, blood insulin was lower. The researchers also compared diets with different types of fat, namely diets high in polyunsaturated fat versus diets high in saturated fat. Polyunsaturated fats are more liquid whereas saturated fats are more solid at a given temperature, due to the hydrogenation of their molecular structure. The type of fat in the diet had no significant effect on insulin binding. The time of the menstrual cycle also had no effect on insulin binding. The type of cells analyzed for insulin receptors were modified erythrocytes (red blood cells) known as ghost cells. Ghost cells have lost their red color so only the cell membrane is visible.

Health aspects, Research, Women, Food and nutrition, Low-fat diet, Low fat diet, Erythrocytes, Red blood cells, Menstruation, Insulin, High-carbohydrate diet, High carbohydrate diet, Insulin receptors

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