In a recent study, metabolic effects of meals with varying glycemic index (GI) were evaluated. In a group of healthy volunteers, glucose, insulin and leptin responses to two contrasting breakfast cereals were measured. Leptin is a hormone produced by fat cells that indicates the degree of hunger to the hypothalamus of the brain. Lower leptin levels trigger a sense of satiety and decreased hunger.
Meals were provided on two separate occasions in random order after a 12-hour overnight fast, and consisted of 50 g of available carbohydrate from either Corn Flakes (Kellogg's), or Fiber One (General Mills). Blood samples were obtained at rest, and 30, 60, 90 and 120 min after eating. The GI was calculated from the glucose response to the test meal normalized against a 50 g oral glucose load.
The average GI for Corn Flakes was 125 and 49 for Fiber One. These meals were classified as high GI and low GI, respectively, and were significantly different from each other. The insulin response following the low glycemic meal was significantly reduced compared to the high glycemic meal. The high glycemic meal significantly suppressed circulating leptin levels compared to the low glycemic meal.
Lower insulin response and higher circulating leptin levels suggest that low glycemic meals promote a post-meal environment that is favorable for reduced food consumption; this may be advantageous in the control of obesity and related disorders, including insulin resistance and type 2 diabetes.
Ann Nutr Metab 2007 Dec 10;51(6):512-518
Friday, January 9, 2009
Dietary fiber from whole grains protects against cancer of the small intestine
In a new study published in the journal Gastroenterology, researchers conducted a large population study to determine the relationship between intake of dietary fiber and the incidence of small intestinal cancer. Dietary information was gathered from 293,703 men and 198,618 women who participated in the National Institutes of Health-AARP Diet and Health Study.
After eight years of follow-up it was determined that dietary fiber intake was associated with a lower risk of small intestinal cancer. The group with the highest intake of fiber from grains had a 49% lower risk of small intestine cancer compared to the group with the lowest intake. Likewise, the group that consumed the most whole-grain foods had a 41% lower incidence of the disease compared to the group eating the least whole-grain foods.
Since similar dietary factors and results have been seen in studies involving cancer of the large intestine, it is likely that grain fiber and whole grain foods may protect against lower gastrointestinal cancers.
Gastroenterology. 2008 Oct;135(4):1163-7.
After eight years of follow-up it was determined that dietary fiber intake was associated with a lower risk of small intestinal cancer. The group with the highest intake of fiber from grains had a 49% lower risk of small intestine cancer compared to the group with the lowest intake. Likewise, the group that consumed the most whole-grain foods had a 41% lower incidence of the disease compared to the group eating the least whole-grain foods.
Since similar dietary factors and results have been seen in studies involving cancer of the large intestine, it is likely that grain fiber and whole grain foods may protect against lower gastrointestinal cancers.
Gastroenterology. 2008 Oct;135(4):1163-7.
Vitamin E and Respiratory Tract Infections
Respiratory illnesses, including the common cold, can be debilitating and lead to complications and death in the elderly. A study published in the August 18, 2004, issue of the Journal of the American Medical Association found vitamin E to be protective against upper respiratory infections.
Four hundred fifty-one individuals aged 65 and older at 33 long-term care facilities completed a course of 200 IU of vitamin E per day or a placebo from April 1998 to August 2001. In addition, all of the subjects received a multivitamin that provided 50 percent of the recommended daily allowance for essential vitamins and minerals. The incidence of lower respiratory infections, such as acute bronchitis and pneumonia, and upper respiratory tract infections, including cold, influenza, sore throat, middle ear infection and sinusitis, was documented over the course of the trial.
The subjects who received vitamin E acquired fewer respiratory tract infections than those who did not receive the vitamin. Participants who received the vitamin experienced a 20 percent decreased risk of acquiring the common cold, which accounted for 84 percent of the upper respiratory infections reported. In addition, participants taking vitamin E had fewer colds per person. Although vitamin E showed no significant effect on lower respiratory tract infections, the protective effect of vitamin E supplementation on upper respiratory tract infections observed in this group merits further investigation and suggests important implications for the well-being of the elderly.
JAMA. 2004;292:828-836
Four hundred fifty-one individuals aged 65 and older at 33 long-term care facilities completed a course of 200 IU of vitamin E per day or a placebo from April 1998 to August 2001. In addition, all of the subjects received a multivitamin that provided 50 percent of the recommended daily allowance for essential vitamins and minerals. The incidence of lower respiratory infections, such as acute bronchitis and pneumonia, and upper respiratory tract infections, including cold, influenza, sore throat, middle ear infection and sinusitis, was documented over the course of the trial.
The subjects who received vitamin E acquired fewer respiratory tract infections than those who did not receive the vitamin. Participants who received the vitamin experienced a 20 percent decreased risk of acquiring the common cold, which accounted for 84 percent of the upper respiratory infections reported. In addition, participants taking vitamin E had fewer colds per person. Although vitamin E showed no significant effect on lower respiratory tract infections, the protective effect of vitamin E supplementation on upper respiratory tract infections observed in this group merits further investigation and suggests important implications for the well-being of the elderly.
JAMA. 2004;292:828-836
Multivitamins and Healthy Immune Function
A recent article published in the British Journal of Nutrition summarizes the roles of select vitamins and trace elements in immune function.
Adequate intakes of micronutrients are required for the immune system to function efficiently. Micronutrient deficiency suppresses immunity by affecting antibody responses, leading to imbalances in the immune system. This situation increases susceptibility to infections, which increases disease and death risk. In addition, infections aggravate micronutrient deficiencies by reducing nutrient intake, increasing losses, and interfering with utilization by altering metabolic pathways. Inadequate intakes of micronutrients are common in people with eating disorders, smokers (active and passive), individuals with chronic alcohol abuse, certain diseases, during pregnancy and lactation, and in the elderly.
Micronutrients contribute to the body's natural defenses on three levels by supporting physical barriers (skin/mucosa), cellular immunity, and antibody production. Vitamins A, C, E, and the mineral zinc assist in enhancing the skin barrier function. Vitamins A, B6, B12, C, D, E, and folic acid, and the minerals iron, zinc, copper and selenium work synergistically to support the protective activities of the immune cells. Finally, all these micronutrients, with the exception of vitamin C and iron, are essential for the production of antibodies.
Overall, inadequate intake and status of these vitamins and minerals may lead to a suppressed immune system, which increases the risk of infections and aggravates malnutrition. Therefore, supplementation with a multivitamin that includes these micronutrients can support the body's natural defense system by enhancing all three levels of immunity.
Br J Nutr. 2007 Oct;98 Suppl 1:S29-35.
Adequate intakes of micronutrients are required for the immune system to function efficiently. Micronutrient deficiency suppresses immunity by affecting antibody responses, leading to imbalances in the immune system. This situation increases susceptibility to infections, which increases disease and death risk. In addition, infections aggravate micronutrient deficiencies by reducing nutrient intake, increasing losses, and interfering with utilization by altering metabolic pathways. Inadequate intakes of micronutrients are common in people with eating disorders, smokers (active and passive), individuals with chronic alcohol abuse, certain diseases, during pregnancy and lactation, and in the elderly.
Micronutrients contribute to the body's natural defenses on three levels by supporting physical barriers (skin/mucosa), cellular immunity, and antibody production. Vitamins A, C, E, and the mineral zinc assist in enhancing the skin barrier function. Vitamins A, B6, B12, C, D, E, and folic acid, and the minerals iron, zinc, copper and selenium work synergistically to support the protective activities of the immune cells. Finally, all these micronutrients, with the exception of vitamin C and iron, are essential for the production of antibodies.
Overall, inadequate intake and status of these vitamins and minerals may lead to a suppressed immune system, which increases the risk of infections and aggravates malnutrition. Therefore, supplementation with a multivitamin that includes these micronutrients can support the body's natural defense system by enhancing all three levels of immunity.
Br J Nutr. 2007 Oct;98 Suppl 1:S29-35.
Vitamin C and E Supplements Lower Diabetic Retinopathy Risk
A study published in the American Journal of Clinical Nutrition examined 1,353 type 2 diabetics who were diagnosed from 1993 to 1995. Data from these subjects revealed no association of diabetic retinopathy with vitamins C and E from food alone, but a decreased risk was found among those who reported long-term (> 3 years) use of vitamin C or E or multivitamin supplements. Compared to those who did not report supplement use, long-term supplement users experienced a two-fold reduction in the risk of developing diabetic retinopathy.
Although there had previously been evidence of this association from in vitro, animal, and short-term research, this was the first epidemiologic study on retinopathy to show the same protective effect associated with supplemental vitamin C and vitamin E.
American Journal of Clinical Nutrition, Vol. 79, No. 5, 865-873, May 2004
Although there had previously been evidence of this association from in vitro, animal, and short-term research, this was the first epidemiologic study on retinopathy to show the same protective effect associated with supplemental vitamin C and vitamin E.
American Journal of Clinical Nutrition, Vol. 79, No. 5, 865-873, May 2004
Magnesium intake and risk of type 2 diabetes
A meta-analysis recently published in the Journal of Internal Medicine analyzed the association between magnesium intake and the risk of type 2 diabetes. The meta-analysis involved studies of magnesium intake (both from foods only and from foods and supplements) published between 1966 and 2007. Seven studies meeting the criteria were identified, and in total they included 286,668 participants and 10,912 cases. All but one study found an inverse relation between magnesium intake and risk of type 2 diabetes, and in four studies the association was statistically significant. Overall, an increase of 100 mg of magnesium per day resulted in a 15% reduction in overall risk of type 2 diabetes.
Based on these studies, magnesium intake is inversely associated with incidence of type 2 diabetes. This finding suggests that increased consumption of magnesium from supplements and foods such as whole grains, beans, nuts, and green leafy vegetables may reduce the risk of type 2 diabetes.
J Intern Med. 2007 Aug;262(2):208-14
Based on these studies, magnesium intake is inversely associated with incidence of type 2 diabetes. This finding suggests that increased consumption of magnesium from supplements and foods such as whole grains, beans, nuts, and green leafy vegetables may reduce the risk of type 2 diabetes.
J Intern Med. 2007 Aug;262(2):208-14
Whey improves insulin response in type 2 diabetics
In a study published in the American Journal of Clinical Nutrition, researchers evaluated whether supplementation of high-glycemic meals (GI) with whey proteins would increase insulin secretion and improve blood glucose control in type 2 diabetics.
Subjects with type 2 diabetes were served a high-GI breakfast and lunch supplemented with whey on one day, and lean ham and lactose on another day.
When whey was included in the meal, insulin responses were significantly higher for both breakfast and lunch than when it was not included. In addition, blood glucose response was significantly reduced after lunch with the inclusion of whey.
In type 2 diabetics, whey added to high-GI meals may increase insulin secretion and improve blood glucose clearance after a meal. This can be of significant benefit to those with reduced insulin secretion and/or compromised blood glucose regulation.
American Journal of Clinical Nutrition, Vol. 82, No. 1, 69-75, July 2005
Subjects with type 2 diabetes were served a high-GI breakfast and lunch supplemented with whey on one day, and lean ham and lactose on another day.
When whey was included in the meal, insulin responses were significantly higher for both breakfast and lunch than when it was not included. In addition, blood glucose response was significantly reduced after lunch with the inclusion of whey.
In type 2 diabetics, whey added to high-GI meals may increase insulin secretion and improve blood glucose clearance after a meal. This can be of significant benefit to those with reduced insulin secretion and/or compromised blood glucose regulation.
American Journal of Clinical Nutrition, Vol. 82, No. 1, 69-75, July 2005
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