Brain Serotonin,Carbohydrate-Craving,Obesity and Depression

Serotonin-releasing brain neurons are unique in that the amount of neurotransmitter they release is normally controlled by food intake: Carbohydrate consumption-acting via insulin secretion and the “plasma tryptophan ratio” - increases serotonin release; protein intake lacks this effect. This ability of neurons to couple neuronal signaling properties to food consumption is a link in the feedback mechanism that normally keeps carbohydrate and protein intakes more or less constant. However, serotonin release is also involved in such functions as sleep onset, pain sensitivity, blood pressure regulation, and control of the mood. Hence many patients learn to overeat carbohydrates (particularly snack foods, like potato chips or pastries, which are rich in carbohydrates and fats) to make themselves feel better. This tendency to use certain foods as though they were drugs is a frequent cause of weight gain, an d can also be seen in patients who become fat when exposed to stress, or in women with premenstrual syndrome, or in patients with “winter depression,” or in people who are attempting to give up smoking. (Nicotine, like dietary carbohydrates, increases brain serotonin secretion; nicotine withdraw al has the opposite effect.) It also occurs in patients with normal-weight bulimia. Dexfenfluramine constitutes a highly effective treatment for such patients. In addition to producing its general satiety-promoting effect, it specifically reduces their overconsumption of carbohydrate-rich (or carbohydrate-and fat-rich)foods.     

Toward Comprehensive Obesity Prevention Programs in Native American Communities

Obesity is a particularly important challenge to the health status of Native Americans. This challenge is manifest in the increasing rates of non-insulin-dependent diabetes mellitus among Native Americans. Most studies of Native American infants, preschool children, schoolchildren, and adults have confirmed a high prevalence of over weight Historical studies suggest that for many Native American communities the high rates of obesity are a relatively recent phenomenon. The specific reasons for the increase in obesity among Native Americans have not been determined, although it has been hypothesized that Native Americans have a genetic predisposition to over weight in a “westernized” environment of abundant food and decreased energy expenditure. Few detailed studies of diet or of physical activity levels of contemporary Native Americans have been published. Community-based interventions to modify diet and activity levels to prevent obesity in Native American communities are needed. Preliminary evidence from two formative school-based programs in the Southwest suggest that Native American communities are receptive to school-based interventions, and that such programs may be able to slow the rate of excess weight gain and to improve fitness in schoolchildren. Because of the cultural diversity among Native Americans, future studies should focus on collecting community- and region-specific data, and should emphasize the need for obesity prevention through culturally appropriate community-and school-based behavioral interventions.     

Are Child Eating Patterns Being Transformed Globally?

Objective: To examine the extent to which child dietary patterns and trends are changing globally. Research Methods and Procedures: Diets of children 2 to 19 years of age were studied with nationally representative data from Russia and the United States, nationwide data from China, and regional data from metropolitan Cebu, Philippines. Twenty‐four‐hour dietary recalls were examined at several points in time to examine trends in calories consumed away from home, snacking behavior, and soft drink and modern fast food consumption. Urban—rural trends were compared. Results: U.S. and Cebu youth consume more than one‐third of their daily calories and a higher proportion of snack calories from foods prepared away from home. In contrast, away from home food consumption is minimal in Chinese and Russian children. U.S. and Cebu youth consume about one‐fifth of their total daily energy from snacks, but snacks provide a much lower proportion of energy in Russia (～16%) and China (where snacks provide only ～1% of energy). Fast food plays a much more dominant role in the American diet (～20% of energy vs. 2% to 7% in the other countries), but as yet does not contribute substantially to children's diets in the other countries. Urban—rural differences were found to be important, but narrowing over time, for China and Cebu, whereas they are widening for Russia. Discussion: This research suggests that globalization of the fast food and other modern food sectors is beginning to affect child eating patterns in several countries undergoing nutrition transition. However, the contribution of fast food and soft drinks to the diet of children remains relatively small in China, Russia, and Cebu, Philippines, relative to the United States.     

Relative lower extremity length in Mexican American and in American black and white youth

Stature, sitting height, estimated leg (subischial) length and the sitting height/stature ratio are compared in Mexican American, American White and American Black boys 9 through 14 years of age and girls 12 through 17 years of age. Mexican American youth are shorter in stature and have absolutely shorter lower extremities. The sitting height of Mexican American youth is similar to that of Black youth and shorter than that of White youth. The sitting height/stature ratio is virtually identical in Mexican American and White youth, indicating similar proportions of lower extremities to stature. In contrast, Black youth have absolutely and relatively longer lower extremities than Mexican American and White youth. These results would thus seem to suggest that reference data for the body mass index (BMI) based on American White youth can be used with Mexican American youth, while race-specific values may be necessary for American Black youth. However, ethnic variation in physique, perhaps frame size, may be a factor which should be more systematically considered in evaluating the utility of the body mass index.