Relation of body size and composition to clinical biochemical and hematologic indices in US men and women

Article Abstract:

Normal ranges have been established for various biochemical and hematologic indices, such as blood hemoglobin and cholesterol. The human body normally maintains these substances within a relatively narrow range; small but significant deviations from this range may be very important to the health of the individual. Some previous research has suggested that body size and body composition may have a predictable effect on certain biochemical indices, but the studies included only small numbers of subjects who were ill, anemic, and/or malnourished. A large study of nonhospitalized American men and women was conducted as part of the First National Health and Nutrition Examination Survey (NHANES I); the association between body size and composition and blood indices were evaluated. Three measures of iron status; hemoglobin, hematocrit, and total iron-binding capacity, were found to be higher in persons of greater weight, height, lean body mass (LBM), and skinfold thickness (a measure of body fat). Higher total blood cholesterol was measured in persons of greater weight, body fat, and LBM; central body obesity was most strongly linked to higher cholesterol. These results suggest that aspects of body size and composition may warrant consideration for both the clinical assessment of patients and interpretation of epidemiological research studies. For example, marginally low hemoglobin and hematocrit values may be of no concern in a small, slight woman but may indicate anemia in a tall, heavy woman. Research with different population groups has shown a similar trend. Marginally low hemoglobin levels had no adverse effect on the outcome of pregnancy in Asian women, but were detrimental during pregnancy in white women. This is attributed to the tendency of white women to be larger and heavier compared with Asian women. (Consumer Summary produced by Reliance Medical Information, Inc.)

Standards, Medical laboratories, Biomedical laboratories, Body weight, Hematology, Clinical chemistry

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Do obese individuals gain weight more easily than nonobese individuals?

Article Abstract:

There continues to be much interest in and controversy about energy metabolism and weight gain in obese persons. Some individuals who are overweight assert that they gain weight very easily, while some thin persons claim they can eat as much as they want and never gain a pound. This has led to the question, Which group gains weight more readily when overfed, obese or thin people? Research studies found many years ago that all subjects, whether overweight or thin, did gain weight when fed more calories than they used, and controlled studies reported that the amount of weight gained directly reflected the total excess calories consumed. This article presents a review of five studies in which subjects were intentionally overfed for periods of 2 to 12 weeks in a controlled environment. The total number of subjects in all studies combined was 63; approximately half were men and half were women. All the studies analyzed the body composition of subjects, which involves estimating the proportions of lean and fat tissues in the body. The analysis revealed that contrary to popular opinion, larger and fatter persons actually need to eat more excess calories to gain a pound than do thin people. This means than thin people gain weight more easily than obese people. The reason for this is that in general, overweight people tend to gain more fat tissue, and thin people are more likely to gain lean tissue. A pound of fat contains more energy than a pound of muscle, therefore one has to eat more calories to gain the pound of fat. More specifically, the energy cost of gaining 1 gram of fat is 12 calories, whereas the energy cost of gaining 1 gram of lean tissue is less than 2 calories. (Consumer Summary produced by Reliance Medical Information, Inc.)

Obesity, Energy metabolism, Adipose tissues, Adipose tissue

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Vitamin C and other compounds in vitamin C rich food in relation to risk of tuberculosis in male smokers

Article Abstract:

Vitamin C and other compounds in vitamin C-rich food are discussed as related to risk of tuberculosis in male smokers as studied in 167 incident cases of tuberculosis during 6.7 years' follow-up of 26,975 Finnish men for whom baseline dietary data were taken. A very statistically significant inverse association was seen between calculated vitamin C intake and incidence of tuberculosis, but adjustment of nondiet factors weakened the association, and it proved nonsignificant. Findings showed associations of this sort can be confounded without proper control. Those who consumed more fruits and vegetables, even in low in vitamin C, had lower tuberculosis incidence.

Finland, Health aspects, Statistical Data Included, Research, Methods, Prevention, Vitamin E, Smoking, Tuberculosis, Diet, Nutritionally induced diseases, Nutrition disorders, Vitamin C, Epidemiological research, Cross sectional studies, Experimental design, Research design, Beta carotene

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