Human dietary studies

Agarwal, S. and Rao, A.V., Tomato lycopene and low density lipoprotein oxidation a human dietary intervention study. Lipids, 33, 981, 1998. 

One common objective of an LSMBS is to refine the estimates of actual exposure of consumers to ingredients or impurities in one or more products. For example, study results might be intended to determine a realistic human dietary exposure to pesticide residues in fresh fruits and vegetables. The advent of the Food Quality Protection Act of 1996 (FQPA) has produced an enhanced focus on the exposure of children to pesticides. A well-designed and implemented LSMBS would afford the opportunity to delineate better the exposure and risk to children and other population subgroups. The LSMBS would provide consumer-level data at or near the point of consumption, allowing the refined, relevant, and realistic assessments of dietary exposure. 

Phytochemicals have been the subject of many studies evaluating their effects in relation to common chronic human illnesses such as cancer and cardiovascular diseases. These studies encounter difficulties in using this information to influence the dietary patterns of consumers because in the past they have used models or experiments with animals. However, in the last decade, researchers have moved away from animal studies in favour of human cell models or human intervention studies. Scientists still need to determine the likely incidence of illness from exposure to known amounts of a given natural compound in the diet and specifically in relation to the complex matrices of whole foods. Therefore, it is inevitable that some animal studies have to be continued for toxicological studies. 

We have conducted two human metabolic studies (5,6) to compare the effects of increasing phosphorus intake on calcium utilization in healthy young adults maintained at low (ca. 400 mg/day) and high (ca. 1200 mg/day) levels of calcium intake. Increasing dietary phosphorus, as orthophosphate, caused a slight reduction in fecal calcium and a substantial reduction in urinary calcium losses (Table III). 

Since this increased calcium loss, the quality of dietary protein may be important in conserving body calcium in the bone reservoir via the kidney. Human renal studies have corroborated animal data in-so-far as calcium excretion as influenced by urinary acidity is concerned. This was emphasized by Marone et al. (15) who reported increased excretion of calcium in the acidotic dog and by Zemel, et al. (27) who studied calcium filtration by the kidney. They fed subjects low or high-protein (50 or 150 g/d) diets, then compared... 

Human Health At present, studies on the impact of POPs on human health are very limited in China. Most of the existing literature is focused on dietary studies, as the food chain is considered a major pathway for POPs to effect human health. Information on human health effects such as body burden and metabolism is insufficient and generally extrapolated from modeling data because few doctors have been involved in research on POPs exposures in China. Other exposures through respiration and skin as well as air and soil are seldom studied. 

Mukhtar, H., and Ahmad, N., 2000, Tea polyphenols prevention of cancer and optimizing health, Am. J. Clin. Nutrition 71 suppl.) 1698S-1702S. Neuhouser, M. L., 2004, Dietary flavonoids and cancer risk evidence from human population studies, Nutr. Cancer 50 1-7. 

There is growing evidence from human feeding studies that the absorption and bioavailability and thus bioactivity of phenolic compounds and flavonoids are very much dependent on the nature of their chemical structure. Their chemical classification and dietary occurrence is briefly discussed in the following section. 

There is now emerging data that specific dietary flavonoids may improve endothelial function by increasing NO bioavailability. Longer term human intervention studies are required to establish a proven benefit on vascular function in healthy subjects as well as those who may be at increased risk of cardiovascular disease. 

Neuhouser ML. 2004. Dietary flavonoids and cancer risk Evidence from human population studies. Nutr Cancer 50 1-7. 

FIG. 12 Effect of dietary lycopene supplements on serum LDL oxidation (SS, spaghetti sauce TJ, tomato juice TO, tomato oleoresin). Bars with different letters are statistically different (p < 0.05). (Tomato lycopene and low density lipoprotein oxidation A human dietary intervention study. Reprinted from Lipids. 1988 33, pp. 981-984 by permission of AOCS Press.)... 

Yang, G. and Xia, Y. 1995. Studies on human dietary requirements and safe range of dietary intakes of selenium in China and their application in the prevention of related endemic diseases. Biomed. Environ. Sci. 8, 187-201. 

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