Dietary factors retention

Substantial individual differences were observed in the response to study breads and the ranges of enterolactone concentration changes in the groups were as follows -54.5-60.0 nmol/1 (placebo), -26.2-101.3 nmol/1 (LP), -19.6-81.8 nmol/1 (HP). This was something that could have been expected as in several studies dietary factors have explained only 10% of the variation in serum enterolactone (Vanharanta et al, 2002b Kilkkinen et al., 2001). This gives further support to the major role of intestinal bacteria in the synthesis of enterolactone. Decreased concentrations of enterolactone may occur due to an increased fiber intake, which may shorten the retention time in the colon and lead to incomplete metabolism of plant lignans. Constipation was earlier shown to be associated with an increased level of serum enterolactone (Kilkkinen et al., 2001). 

Many other dietary factors have been reported to affect calcium bioavailability. Phytate, fiber, cellulose, uronic acids, sodium alginate, oxalate, fat (only in the presence of steatorrhea), and alcohol have been reported to decrease calcium bioavailability (15). Lactose and medium chain triglyceride increase it (15). FTuoride also affects calcium retention primarily by stimulating bone formation thereby decreasing calcium excretion (33-38). The effects of fluoride on calcium utilization have been variable (34,38,39). 

Slanina P, Freeh W, Bemhardson A, et al. 1985. Influence of dietary factors on aluminum absorption and retention in the brain and bone of rats. Acta Pharmacol Toxicol 56 331-336. 

Limited data are available about the effects of individual dietary components on absorption, and consequently the requirement, of Mn. Dietary protein and phosphorus levels (33), calcium level (34) and the effect of a partial substitution of soy protein for meat (28) have been tested in balance studies without any obvious effect of Mn absorption or retention. However, since the main route of excretion is via the bile, the conventional balance technique is probably not sensitive enough to identify dietary factors that influence Mn absorption. 

A simplified description of the etiology of dental caries involves metabolism of sugars by oral microorganisms to acids which gradually dissolve tooth enamel. However, it is now recognized that a number of dietary factors and nutrient interactions can modify the expression of dental caries (Herod, 1991). The cariogenic potential of food is infiuenced by its composition, texture, solubility, retentiveness, and ability to stimulate saliva flow (Morrissey et al, 1984). 

Dietary uptake, retention, and tissue distribution of Mn, Co, and Cs in the rainbow trout have been studied, because this fish is widely distributed in European waterways. These radionuclides present a special interest from a biological standpoint, because Cs is biochemically analogous to K and Mn and Co are classified among the ten vital elements for life. The theoretical values of the steady-state trophic transfer factor (TF) were significantly lower than one for Mn and Co, indicating that these radionuclides are not being biomagnified in their transfer to trout, while Cs showed the opposite. At the end of the uptake phase (42 days), the... 

Suzuki, S., Taguchi, T. and Yokohashi, G. (1969) Dietary factors influencing upon the retention rate of orally administered ii5mcdci2 in mice with special reference to calcium and protein concentrations in diet. Ind. Health 7, 155-160. 

Susenbeth A, Dickel T, Diekenhorst A and Hohler D (1999), The effect of energy intake, genotype and body weight on protein retention in pigs when dietary lysine is the first-limiting factor , J Anim Sci, 77, 2985-2989. 

Calcium retention is dependent on two factors, absorption and excretion. Normal subjects have been observed to have apparent calcium absorptions of 23 (sd = 12) to 27 (sd = 17) percent of the calcium from normal diets (21,22). For 20 women aged 55 to 65 consuming 629 (se = 92) milligrams dietary calcium daily, the apparent absorption was 32.1 (se = 1.9) percent (23). An apparent calcium absorption of 29.5 percent (n = 130) may be calculated from data published by Heaney et al. (15). Apparent absorption values from 29 to 42 percent may be calculated from data published by Linkswiler (24,25). However, much lower apparent absorption values of 6 to 15 percent may also be calculated from data published from the same laboratory (26). Although there is considerable variability in the apparent absorption values determined from many studies, a conservative value of 25 percent seems realistic for normal people consuming typical diets. 

Age, calcium intake, hormonal status, exercise and vitamin status have all been implicated in the development of osteoporosis. Estrogen levels represent an important factor in skeletal calcium retention and homeostasis. In therapeutic trials in which post-menopausal women were given daily doses of estrogens, such therapy has been demonstrated to be partially effective in reducing the rate of bone resorption. However, this therapy has the concomitant hazard of endometrial cancer (10). Vitamin D and its hormones have been given considerable attention in the more recent studies. Without adequate dietary and tissue levels of such vitamins, calcium absorption and bone status will be impaired. 

In the event of dietary Ca abundance, Ca in excess of adequate circulating concentrations is deposited in the skeleton. This occurs to the extent of the body s ability to store Ca, and any excess beyond this threshold is excreted. Accrual of Ca into bone is governed by such factors as dietary intake (including the absorption, bioavailability, utilization of nutrients and minerals, and other dietary constituents that influence absorption or retention), calciotropic hormones, genetic potential, lifestyle factors, life stage, general health, and the adaptive response to physical/mechanical stimuli within the constraints of metabolic economy. 

There have been relatively few studies on Mn bioavailability from various types of diets as well as from individual factors in the diet. However, to better understand the requirement of Mn in humans it is essential to obtain such information. While Mn deficiency in humans appears to be rare (see Chapter by Keen et al.), our knowledge about the signs of human Mn deficiency as well as our means to clinically assess Mn status is very limited. The physiological requirement of Mn, i.e., the amount that must be absorbed to balance the daily excretion and retention in growing subjects, is not known. The observed whole body turnover rate in human adults (a half-life of about 40 days) and available estimates of total body Mn content (20 mg) (26) speaks for a daily turnover of about 0.25 mg. With a low degree of absorption, the dietary requirement will be much higher. 

Therefore, it is important to know the bioavailahility of (/-linolenate (i.e., the portion of consumed (/-linolenate that is actually available for desaturation-chain elongation). It is also important to understand the factors that are most likely to influence the partitioning of dietary a-linolenate toward p-oxidation or carbon recycling compared to retention inthe body as an n-3 PUFA. This chapter will provide evidence that p-oxidation and carbon recycling consume the majority of dietary a-linolenate in two models of mammalian fetal/neonatal development. 

Among other nutritional factors potentially interacting with Pb, those of the vitamin D endocrine system are probably the more significant. Unlike Ca and Fe, however, the vitamin D interaction has been much less studied in human populations and is even less understood. Vitamin D in the form of a dietary nutrient or as an endogenous substance biosynthesized in situ in amounts proportional to the intensity of solar stimulation has been reported to be variably associated with Pb uptake, retention, and toxicity. 

As a result of the introduction of more refined foods and dietary trends which accompany affluence in modern society, teeth are more vulnerable to decay than ever before. There is little evidence of caries in the teeth of prehistoric man and the disease is of rare occurrence in India, Africa and Indo-China but is found in 98% of the populations of Europe and North America. Although many features of diet contribute to the prevalence of caries, Nizel has summarized present-day views as follows (1) the major cariogenic foodstuff is sucrose (2) the major physical factor in caries is retention of sucrose on the tooth surface (3) the major cariogenic food habit is frequency of eating. 

Radioiodine uptake and retention by the thyroid gland are altered by a number of factors, including age, amounts of dietary and physiologic state. 

Causal factors of essential hypertension include obesity, anxiety/stress, Na intake and alcohol. Hypertension is linked to obesity because obese people are thought to have a higher intake of Na. Na retention causes an increase in arteriole smooth muscle tone. The effect of alcohol intake on blood pressure starts at above three drinks per day. The mechanism has not been established, it is thought to act by increasing red cell volume and therefore blood viscosity. The following dietary components may reduce blood pressure K+, Ca +, polyunsaturated FAs, Mg + and vegetarianism. 

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