Diets, lead sources

The proportion of zinc contributed by dairy products also has increased over the years, making this group the second leading source in the food supply. In recent decades, dairy products have contributed approximately 20 percent of the total zinc. On the other hand, the proportion of zinc from grain products has decreased by about one-half since the beginning of the century when it provided 27 percent of the total zinc. In the early 1940 s, grain products dropped from second to third place as a source of zinc in the American diet. 

A healthy diet goes a long way in reducing the damage from exposure to lead sources by keeping lead from being absorbed by the body. For a discussion of specific nutritional measures, see Chapter 6. 

The amino acids absorbed by the animal are required for the synthesis of body proteins. The efficiency with which this synthesis is effected depends partly on how closely the amino acid proportions of the absorbed mixture resemble those of the body proteins and partly on the extent to which the proportions can be modified. The biological value of a food protein therefore depends upon the number and kinds of amino acids present in the molecule the closer the amino acid composition of the food protein approaches that of the body protein, the higher will be its biological value. Animals have little ability to store amino acids in the free state, and if an amino acid is not required immediately for protein synthesis then it is readily broken down and either transformed into a non-essential amino acid or used as an energy source. Since essential amino acids cannot be effectively synthesised in the animal body, an imbalance of these in the diet leads to wastage. Food proteins with either a deficiency or an excess of any particular amino acid will tend to have low biological values. 

Fig. C-20. Wheat bread. Wheat Is the leading source of carbohydrates In the American diet. (Courtesy, National Film Board of Canada)...

Fig. C-21. Corn ranks second to wheat as the leading source of carbohydrates in the American diet. Shown above Sweetcorn going Into the micro-...

The milk food group makes important contributions to the diet Milk and milk products are the leading source of calcium and a good source of phosphorus. Also, they provide high-quality protein, the fat-soluble vitamins—A, D (when fortified), F, and K, and all the water-soluble vitamins. Lowfat or skim-milk products fortified with vitamins A and D have essentially the same nutrients as whole milk products, but with fewer calories. 

Gulson et al. (1998) used measured lead isotope ratios (207Pb/206Pb and 206Pb/204Pb) in mothers breast milk and in infants blood to establish that, for the first 60-90 days postpartum, the contribution from breast milk to blood lead in the infants varied from 36% to 80%. Maternal bone and diet appear to be the major sources of lead in breast milk. Mean lead concentration ( standard deviation) in breast milk for participants in the study was 0.73 0.70 pg/kg. 

O Ketoacidosis is a dangerous condition that is characterized by the acidification of the blood and an acetone odour on the breath. The condition occurs when levels of oxaloacetic acid for the citric acid cycle are low. This leads to a buildup of acetyl CoA molecules, which the liver metabolizes to produce acidic ketone bodies. Since carbohydrates are the main source of oxaloacetic acid in the body, high-protein, low-carbohydrate diets have been linked to ketoacidosis. 

The fat content of the US diet has increased very substantially over the past few decades. Currently more than 40% of dietary calories are consumed in the form of fat. This can easily lead to weight gain. The energy required for conversion of dietary fat to fat in adipose tissue involves the loss of only 3% of the calories in the dietary fat. In contrast, the energy requirement for conversion of dietary carbohydrate to fat in adipose tissue involves the loss of 23% of the calories in the dietary carbohydrate. Clearly, dietary fat is a great source of body fat. 

The use of plants for medicinal purposes is an ancient practice. Nature, with its wealth of traditional knowledge has been the source of inspiration for numerous drugs currently used for the improvement of life as well as treatment for a cure. Considering the beneficial role of many plants and fruits, they were included in the human diets. In many instances, the knowledge of the underlying mechanism of action of a particular natural product is incomplete. Continuous investigation can lead to new mechanisms and new structures, which may open up entirely new windows and perspectives. For instance, before the discovery of apicidin and bispyri-dinium diene, it was believed that unless there is a classical chelator for zinc ion, it cannot be a HDAC inhibitor. SAHA has been approved by FDA, which is inspired from the natural product trichostatin. The natural product, romidepsin has also been approved by FDA and many are on clinical trials. Currently, isozyme-selective inhibition for HDAC is at its nascent stage. The invention of some novel molecules or invention of some novel natural product structures with synthetic modifications will solve the problem. 

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