Vitamin human subject

Mammals lack the ability to synthesize astaxanthin or convert dietary astaxanthin into vitamin A. Unlike p-carotene, astaxanthin has no pro-vitamin activity in these animals. Astaxanthin has been shown in both in vitro and in a study with human subjects to be effective for the prevention of the oxidation of low-density protein, suggesting that it can be used to prevent arteriosclerosis, coronary artery disease, and ischemic brain development. A number of astaxanthin health products are under study. 

Review of studies on the effect of oxalic acid on calcium bioavailability in rats and in humans indicates that most of the research was done between 1930 and 1950. Decreased availability of calcium in young rats was reported when spinach containing oxalic acid was fed with low calcium diets. The extent of the effect of oxalic acid on calcium availability was shown to be related to levels of calcium and oxalic acid, as well as the presence of vitamin D in the diet. In human studies there was generally no effect of oxalic acid on calcium balance however, in a few studies decreased calcium balances were reported. There is recent evidence that oxalic acid consumed along with a moderately high level of fiber intake may have adverse effects on calcium balance of human subjects. 

When utilization tests were run on a group of 18 male and 7 female human subjects, wide variations in blood level responses were found, particularly among the males.36 [Both in animals (rats) and humans the two sexes respond somewhat differently.] When 134,000 ig. of vitamin A in four different forms, viz., vitamin A alcohol, vitamin A acetate, vitamin A natural ester No. 1, and vitamin A natural ester No. 2, was fed to the group of 18 males on four different occasions, the serum levels found after 6 hours ranged from 178 to 1423 ig. per 100 ml., 122 to 1170 ig. per 100 ml., 110 to 1183 ig. per 100 ml., and 114 to 1230 ig. per 100 ml., respectively. These nearly 10-fold variations in serum levels do not, of course, indicate 10-fold variation in need, but they do show that the vitamin when given in relatively large doses does behave very differently in different individuals. 

An elegant approach using three bacterial genes overexpressed in Desiree achieved a 20-fold increase in total carotenoids to 114 p-g/G DW and a 3600-fold increase in B-carotene to 47 pg/g DW (Diretto et al., 2007). A 250 g serving of these potatoes was estimated to provide 50% of the RDA of vitamin A. Potatoes engineered to have higher zeaxanthin levels were fed to human subjects and the zeaxanthin was found to be readily bioavailable (Bub et al., 2008). 

In human subjects, however, 8 weeks of vitamin E supplementation (800 IU/day) to the diet produced a lowered plasma PGI2 level, as measured by 6-keto-PGF1(X, compared with that in non-supplemented controls [129]. Addition of vitamin E to human platelets in concentrations which resemble normal plasma levels produced a moderately potent but consistent reduction in cyclo-oxygenase activity, with a dose-dependent response up to 1 mM. a-Tocopherol quinone was equally effective in this test [ 130]. 

Olson RE, Chao J, Graham D, Bates MW, and Lewis JH (2002) Total body phylloquinone and its turnover in human subjects at two levels of vitamin K intake. British Journal of Nutrition 87, 543-53. 

Bates CJ (1977) Proline and hydroxyproline excretion and vitamin C status in elderly human subjects. Clinical Science and Molecular Medicine 52,535-43. 

One approach to preventing or managing AMD may involve enhancing the body s free radical defenses. Because the body does not produce antioxidant vitamins or minerals internally, it must continuously receive them from either diet or supplements. Researchers studied nutritional supplementation in human subjects with AMD. Early research demonstrated less vision loss in patients taking oral zinc, but further studies using zinc have been contradictory. Several reports demonstrated protective aspects to AMD patients with increased levels... 

Most of the vitamin in the body is eventually degraded to pyridoxic acid (PX) and excreted in the urine. Vitamin deficiency can result in a decrease in the amount of PX excreted, as illustrated by the data tn Table 9.4. Human subjects who had consumed a B i-sufficient diet were fed a B(,-deficient diet for 45 days. The results... 

A study of 2K human subjects revealed that treatment with three vitamins together (folate, vitamin and vitamin Bu) can provoke a decline of plasma homt>cysteine from an initial level of about 12 piM to the lower level of 8 xM (Naurath ei a]., 1995). A study of 100 men with moderate levels of plasma homocysteine (18-40 pM) involved separate supplements of placebo, folic acid, vitamin 15i2, or vitamin E. Folic add alone resulted in a 40% decline in plasma homocysteine. Vitamin B] alone provoked a 15% decrease in the amino acid, while vitamin... 

Plasma and urinary levels of pantothenic acid have been measured in dietary surveys as well as in controlled studies of the vitamin deficiency. One fairly recent study with human subjects involved the feeding of a pantothenic acid-free diet for 9 weeks. The urinary pantothenic acid levels (4-6 mg/day) in vitamin-sufficient subjects were roughly half that of the intake (10 mg/day). With consumption of the vitamin-free diet, urinary pantothenic acid levels gradually declined to about 0.8 mg/day over the 9-week period (Fry et ai., 1976). Both urinary and blood serum levels of pantothenate have been used to assess dietary status. Values from urinary measurements seem to be somewhat better correlated with intake of this vitamin, than blood measurements data (Berg, 1997). 

Efficiency in vitamin C, unlike the case with most vitamins, is associated with a specific disease. This disease is scurvy. The symptoms of scurvy include swollen or bleeding gums and hemorrhages under the skin. These symptoms occur when the body s ascorbate is depleted to the point where plasma ascorbate levels are under 0.2 mg/100 mi. Controlled studies with human subjects revealed that symptoms of the disease may develop within 4 weeks with the consumption of an ascorbate-free diet. Scurvy is rarely encountered in developed countries, though it may occur in chronic alcoholism. The disease in humans may be prevented by consuming 10 to 15 mg ascorbic acid per day. 

Cobalt has no confirmed nutritional role in mammalian organisms aside from its participation in the corrin ring structure of cobalamins (vitamin B12). Nonetheless, inorganic cobalt is absorbed by the intestine. That this absorption pathway was shared with iron was first suggested by the observation of a mineral-mineral competition 42). The use of radioisotopes of iron in diagnostic tests of absorption for characterizing iron nutrition in human subjects has been advanced (43-45). An excellent correlation between absorption of radioiron and radiocobalt has been reported (43-45). 

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