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Effects of dietary fibre sources on riboflavin absorption
... The bioavailability of riboflavin from various food sources has not been well characterized, but it has been estimated that at least 95% of food flavin can be absorbed per meal [19,20]. It has been shown that dietary fiber can enhance the absorption of riboflavin and therefore increases its bioavailability by slowing down the movement of chyme in the intestine, increasing the interaction time between the riboflavin and the absorption sites [21]. ...
Food components can promote or retard the absorption and metabolism of nutrients and drugs. The extent of food’s effect on the absorption or metabolism of drugs depends on the characteristics of the food, when the food is consumed, whether fluids are taken with the food, and on the characteristics of the individual consuming the food. The efficiency of the diet in meeting nutrient needs and the therapeutic efficacy of drugs are dependent on those interactions.
In 1983, 27 million in the U.S. population (11.7%) were over 65 years of age, and by the year 2050 this number is expected to be nearly double (U.S. Census of Population, 1980). In view of this projection, there is concern for maintaining health and function as late as possible into an individual’s life span. In the maintenance of health and prevention of disease, adequacy of nutrition is an important component. At different stages of life, sufficiency of intakes of nutrients is prescribed by the recommended dietary allowances (National Academy of Sciences, 1980), which have been defined as “the levels of intake of essential nutrients considered, in the judgment of the Committee on Dietary Allowances of the Food and Nutrition Board on the basis of available scientific knowledge, to be adequate to meet the known nutritional needs of practically all healthy persons.” The basis for this definition is discussed in Chapter 1. In the case of adults, the 1980 RDAs are divided into two age categories, namely, 23–50 years and 51 years upwards. It is, however, unlikely that the nutrient requirements of a 50-year-old adult are the same as those of a person of 23 years, and it is even more improbable that a person of 90 years has the same needs as an individual aged 51 years. Acceptance of these broad categories for RDAs underlines the paucity of data on which to base narrower age bands.
The existence of a heat-stable growth factor in yeast extracts was first discovered by Emmett and Luros in 1920. In 1932, Warburg and Christian isolated from yeast a yellow enzyme which contained a non-protein component subsequently shown to be a phosphate ester of an alloxazine derivative. The structure of riboflavin was determined by Kuhn’s group in 1933 and the vitamin was first synthesized by Karrer’s group in 1935.
Nutritional considerations in biotechnology have arisen with the insertion of a synthetic, nutritionally balanced protein gene in potato (Jaynes et al. 1986). Soon, important staple food crops such as potato and wheat can be nutritionally improved by the use of biotechnology (Bajaj 1987, 1990). Techniques such as recombinant DNA and protoplast fusion have been found to be effective in a number of cereals (Cocking and Davey 1987). The transgenic plants obtained by biotechnological methods reveal the molecular organization in plants (Schell 1987) which can be put to effective use in their nutritional improvement. Rice, being the staple food crop of half the world’s population, can derive the maximum nutritional advantage through the utilization of current knowledge on the location of its genes and the cultivation of entire plants from protoplasts. The benefits of such improvement are likely to result in the improvement of the nutritional status of populations most in need.
Along with positive effects of increased fiber in the diet, there have been reports of decreased bioavailability of nutrients. Some nutrients may be bound by fiber and thus rendered unavailable for absorption by the body.
Nutrient and non-nutrient constituents of foods and beverages can interact with drugs such that the predictable effect of the drug is modified. Outcome of drug-food, drug-alcohol, and drug-nutrient interactions include a change in the rate or level of drug absorption, change in the rate of drug metabolism, drug-food or drug-alcohol incompatibilities, as well as drug-induced nutritional deficiencies. Megadoses of vitamins can alter drug responsiveness. Nutrients, particularly vitamins, can be used as drugs, not only in the treatment of nutritional deficiency disease, but also for their pharmacological effects in disorders that may not be due to nutritional factors. A survey of the various possibilities of interactions is given.
The effect of dietary fiber from wheat bran and psyllium gum on the apparent absorption of riboflavin was studied in 12 healthy women. The test fiber was consumed in crackers that contained approximately 7.5 gm fiber from psyllium gum, wheat bran, or a combination of the two sources. Each subject was given a riboflavin load test after consuming one of the three different fiber supplements or a control supplement that contained 1.3 gm fiber. Fractional urine collections were made for 24 hours, and riboflavin was measured by fluorometric techniques. The psyllium gum and combination supplements reduced the 24-hour apparent absorption of riboflavin from 31.8% to 25.4% and 26.1%, respectively (p less than .01). No effect of the wheat bran supplement on riboflavin was detected.
The effects of cellulose, pectin and bran on the bioavailability of pyridoxine (PN) were examined using rat and chick bioassay methods. Dose-response curves for growth, feed consumption, feed efficiency and either lever pyridoxal 5'-phosphate (PLP) or erythrocyte aspartate aminotransferase (Asp-AT) activity and PLP stimulation in vitro were compared among animals fed experimental diets varying in dietary fiber source and suboptimal levels. of PN. In rats, the observed stimulation of growth and feed efficiency by pectin, as compared to cellulose, at suboptimal PN levels was attributed to increased synthesis of vitamin B-6 intestinal microflora. Diets containing pectin markedly increased the fecal vitamin B-6 content. No difference in liver PLP was detected among rats fed various diets. In chicks, 5% dietary pectin resulted in increased feed consumption, but also diarrhea and depressed growth. Asp-AT activities at the lower level of dietary PN showed a significant (P greater than 0.05) but modest stimulating effect of pectin on the apparent bioavailability of PN. Bran resulted in a 17% bioavailability decrease of PN as indicated by growth and feed consumption data in the chick. However, no difference in Asp-AT activity or in vitro PLP stimulation was detected in comparison of responses from bran-fed chicks with the standard responses. These results suggest that the polysaccharides tested did not have important deleterious effects on the bioavailability of pyridoxine.
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