Dietary influences study design

Although much attention has been directed toward the relationship between calcium intake and osteoporosis, little consideration has been given to the possible influence of dietary phosphorus on the development of this disease in either man or animals. In a study designed to determine the optimal concentration of calcium and phosphorus in the diet of adult mice, aging animals were found to undergo a greater loss of bone when the Ca/P ratio was 1 1 than... 

In a well-controlled study designed to assess the influence of the type and amount of dietary lipid on plasma lipid concentrations in endurance athletes, Lukaskl et al. (46) reported that the plasma response to dietary lipid was not attenuated in men who were physically very active. In contrast, Qulg and associates (47) reported that plasma total cholesterol concentration was lower in subjects who exercised and who ate a diet containing 0.4 or 1.4 gm of cholesterol dally. Thus, the influence of diet on the relationship between exercise and plasma lipids remains equivocal. 

This section describes the rationale for the utilization of dietary tryptophan depletion. Also, it reviews a number of studies designed to determine the consequences of acute tryptophan depletion upon a variety of disorders in humans and conditions in animals. The literature contains a plethora of reports utilizing acute tryptophan depletion. Selected examples have been chosen to illustrate the effects or influences of L-tryptophan levels on a variety of behavioral and psychiatric states. 

Similarly, the number and types of tests completed will influence the cost in ways that can be very complex. Recently, the author was involved in designing a proof-of-principle study intended to assess the ability of a dietary supplement to enhance weight loss among subjects instructed to follow a reduced energy diet. Sample size calculations were run for two scenarios, the first using change in body weight as the primary outcome variable, the... 

A critical question concerns the possible value of dietary intervention as a preventive or therapeutic measure. There is little doubt that fat intake influences breast cancer development in rodents at levels which are found in the human diets. However, conclusive evidence is lacking about the quantitative and qualitative aspects of these processes and how fat in diets may be modified to reduce human cancer incidence. It is likely that dietary intervention may prove useful initially as a preventive or therapeutic measure in isolated groups of high risk individuals. As genetic, hormonal, and immunologic risk factors became more clearly defined, individuals at high risk and those with breast cancer may benefit from therapeutic low-fat diets whose efficacy will require assessment in well-designed clinical studies. 

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