Five types of caneberries [evergreen blackberries (Rubus laciniatus), marionberries (Rubus ursinus), boysenberries (Rubus ursinus x idaeus), red raspberries (Rubus idaeus), and black raspberries (Rubus occidentalis)] were analyzed for antioxidant activity by measuring their oxygen radical absorbance capacity (ORAC). In addition, the berries were analyzed for total phenolics, anthocyanins, procyanidins, and ellagic acid content. All of the berries had high ORAC activity ranging from 24 to 77.2 micromol of Trolox equiv/g of fresh berries. Anthocyanin content ranged from 0.65 to 5.89 mg/g, and phenolics ranged from 4.95 to 9.8 mg/g. Black raspberries had the highest ORAC and anthocyanin and phenolic contents. Only red raspberries had detectable amounts of procyanidin oligomers (monomer, dimers, and trimers). All berries had high levels of ellagic acid (47-90 mg/g), but boysenberries had the highest level prior to hydrolysis. The results from this study indicate that these caneberries were high in antioxidant activity and were rich sources of anthocyanins and phenolics.
Basal metabolic rate (BMR), thyroid hormones and protein utilization were measured in six young men participating in a 75-d metabolic study of low zinc intakes. During metabolic period (MP) 1 (12 d) and MP 3 (9 d) the subjects received 16.5 mg Zn/d. During MP 2 (54 d) they received 5.5 mg Zn/d. Nitrogen intake averaged 12.6 g/d. Mean BMR significantly decreased from 1.00 +/- 0.06 to 0.91 +/- 0.05 kcal/(kg X h) (mean +/- SD) with the low zinc diet and tended to increase during period 3. Serum thyroid-stimulating hormone, thyroxine (T4) and free T4 tended to decrease during the low zinc period and to increase when the adequate zinc diet was fed; only the decrease in free T4 was significant at P less than 0.05, however. Among the measures of protein status, urinary urea excretion, serum prealbumin, albumin and retinol-binding protein levels all decreased significantly during the low zinc period. The results suggest that low zinc intakes may be associated with decreases in BMR. In addition, decreases in thyroid hormone levels and alterations in protein utilization may occur.
Zinc absorption and balances were measured in six young men who were confined while participating in a 75-d metabolic study. A diet of conventional food providing either 16.5 or 5.5 mg Zn/d was fed. Apparent absorption of zinc was calculated from the zinc balance data and from the absorption of a zinc stable isotope added to the diet. The apparent zinc absorption calculated from the isotope data was about 25% when 16.5 mg zinc was fed; it increased to about 53 and 49% after 13 and 42 d, respectively, when 5.5 mg zinc was fed. Total zinc absorption fell from 4.1 mg/d to 2.7-2.9 mg/d during the low zinc period, however. This zinc absorption was sufficient to maintain crude zinc balances in five of the six subjects. Neither serum nor urinary zinc levels changed significantly during the period of feeding low levels of zinc. It appears that zinc absorption readily responds to changes in dietary zinc and that an intake of 5.5 mg Zn/d for about 8 wk does not cause serum or urinary zinc level to fall.
The effect of exercise on intestinal absorption of fructose was evaluated in 10 subjects after they consumed four beverages, each containing a total of 50 g carbohydrate: 100% fructose (100F), 95% fructose and 5% glucose (95F), 70% fructose and 30% glucose (70F), and 100% glucose (100G), as well as a water placebo. With 100F and 95F, breath hydrogen, which is an index of incomplete absorption, increased significantly in all subjects. In contrast, hydrogen excretion did not increase in any subject after consumption of 100G or water, or in five of seven subjects who consumed 70F. The rapid increase in hydrogen excretion observed when consumption of 100F was followed by exercise was not noted during a comparable nonexercise trial. These data suggest that intestinal capacity for absorption of fructose is readily saturated after ingestion of amounts as small as 50 g and that exercise, which reduces intestinal transit time, can cause incomplete absorption of fructose.
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