Functional food supplements to ameliorate the secondary complications in high fructose fed diabetic rats.

Functional foods are the most natural and safest source of health ingredients, providing health benefits beyond basic nutrition, and hence can be used as supplements for the prevention of secondary complications in diabetes. Persistent diabetes may cause glycation of various tissue proteins such as of those in lens, kidney, blood, and brain, which may further lead to the development of pathological conditions such as cataract and cardiovascular diseases. This study on adult rats was designed to assess if the functional food supplements A and B (proprietary blends of antioxidant rich plant materials) can reduce secondary complications such as cataract, dyslipidemia, and oxidative stress under severe diabetic conditions. After nine weeks of intervention of the supplements, it was found that the % HbA1c levels in the formulation group B significantly (p < 0.05) lowered (10.9%) followed by those in group A (11.1%) as compared to those in the diabetic fructose control (DFC) group (15.1%); moreover, plasma insulin levels were significantly (p < 0.01) improved in the formulation B group (9.8 mU L-1) as compared to those in the DFC group (8.5 mU L-1). The significantly higher level of plasma TEAC in group B (27.5 mg dL-1) (p < 0.02) and group A (26.6 mg dL-1) (p < 0.05) indicates an improved plasma antioxidants status as compared to that in DFC group (21.7 mg dL-1). Both the formulation groups A and B showed a decrease in AGEs and tryptophan fluorescence, which suggests amelioration of the glycation of lens proteins as compared to that in the DFC group. The present results indicate that the formulations A and B exhibit antiglycating and antioxidant potentials by inhibiting the high fructose-induced glycation in diabetic rats; hence, they may have therapeutic value as functional foods in the effective management of secondary complications associated with severe diabetic conditions.

Changes in zinc uptake in response to ascorbic acid and folic acid in rat liver slices under normal and oxidative stress conditions.

Zinc plays a dual role, as an integral part of metabolic machinery and in defense against reactive oxygen species. Hepatocytes are important sites for zinc metabolism for synthesis of zinc metalloproteins and maintaining its homeostasis. However, the factors influencing post absorptive zinc metabolism under normal and oxidative stress (OS) conditions are not well understood. Using rat liver slices, we conducted a series of four in vitro zinc uptake experiments to study influence of ascorbic acid and folic acid in normal and oxidative stress conditions with Zn concentrations representing deficient to excess states (7.7-30.7 millimole/L). Zinc uptakes under OS at these four zinc levels were lower than the normal conditions. Folic acid showed significant inhibitory effect on zinc uptake under both normal and OS conditions in a dose response manner. Nevertheless, dose response of ascorbic acid at four zinc levels indicated its marked enhancing effect under OS condition. Differences in zinc uptake trend lines between the normal and OS conditions for interaction of both the vitamins narrowed down as the zinc levels increased. Our results suggest that folic acid causes inhibitory effect, while ascorbic acid may be protective in OS with reference to zinc uptake.

Study of factors affecting binding of zinc with albumin at physiological zinc concentrations.

Albumin has very high affinity for many organic and inorganic compounds that may influence albumin bound Zn (ABZn). To get insight of these molecular interactions, the effect of riboflavin, nicotinic acid, thiamine, folic acid, pyruvic acid and glucose on ABZn were studied. The ABZn was separated from the unbound zinc using equilibrium dialysis and estimated using atomic absorption spectrometer. At therapeutic zinc concentrations, folic acid and thiamine significantly enhanced the ABZn (p < 0.010), while nicotinic acid inhibited zinc binding to albumin. Folic acid was found to enhance the ABZn also at lower zinc concentrations representing physiological levels of plasma zinc (138-150 micromoles) (p < 0.05).

Comparative in vitro uptake of zinc by erythrocytes of normal vs Type 2 diabetic individuals and the associated factors.

Diabetes is an oxidative stress-related disorder in which erythrocyte zinc uptake may vary as compared to healthy individuals. Since zinc is one of the important antioxidant trace metals, some functional indices of erythrocyte zinc status, ie in vitro zinc uptake, osmotic fragility and glucose uptake, were compared in Type 2 diabetic subjects (n=43) and healthy controls (n=22). The associations of these indices with plasma levels of antioxidants and micronutrients were examined. The trace metals were analyzed by atomic absorption spectrophotometer. Vitamins were estimated using spectrophotometric and spectroflourometric methods. In vitro zinc uptakes of healthy subjects were 17 to 52% higher (p<0.01) than those for diabetic subjects. The osmotic fragility for diabetic cells was 2.2 to 1.5 times higher than the healthy cells in 0.85-0.5% NaCl solutions (p<0.05). Percent hemolysis at 0.75, 0.65 and 0.55% NaCl had significant negative correlations (p<0.05) with in vitro zinc uptakes and that at 0.50% NaCl had a positive correlation with HbA1c levels (p<0.05). The in vitro zinc uptakes of erythrocytes in healthy subjects showed a strong negative correlation (p<0.01) with percent hemolysis at 0.75, 0.65 and 0.55% NaCl, a positive correlation with plasma zinc (r=0.33, p<0.05) and a strong negative correlation with plasma selenium and iron, hemoglobin and serum ceruloplasmin indicating antagonistic behavior of copper, iron and selenium with zinc uptake (p<0.01). Furthermore, erythrocyte super oxide dismutase (SOD), plasma ascorbic acid and status of riboflavin and thiamine were negatively correlated with in vitro zinc uptakes of erythrocytes in healthy subjects (p<0.01). These associations in the diabetic subjects were weaker than normal. Erythrocyte zinc uptake and osmotic fragility could be biomarkers of long-term zinc status and decrease of zinc uptake may be one of the features of diabetic patients.

Are lifestyle factors good predictors of retinol and vitamin C deficiency in apparently healthy adults?

OBJECTIVE: To examine interrelationships between (1) dietary habits, (2) socioeconomic and (3) environmental factors, and their impact on plasma retinol and plasma ascorbic acid. DESIGN: Cross-sectional study on adults from Western India. SETTING: Rural, semi urban, urban higher/middle/lower socioeconomic regions (HSE/MSE/LSE) having diverse dietary habits and environmental conditions. SUBJECTS: A total of 214 men and 108 women (20-50 y), apparently healthy and non-anemic. MAIN OUTCOME MEASURES: Food intake by food frequency questionnaire, weight, height, age, smoking, environmental score, education, income, plasma retinol and plasma ascorbic acid. RESULTS: Mean plasma retinol in women (24.84+/-5.1 microg/dl) and men (24.75+/-4.53 microg/dl) were not significantly different and 21% had plasma retinol below 20 microg/dl. Mean plasma ascorbic acid in women (0.35+/-0.12 mg/dl) and men (0.30+/-0.12 mg/dl) was similar with 75% having plasma ascorbic acid below 0.4 mg/dl. Vitamin A intake (as retinol equivalent) and plasma retinol showed a significant dose response (P<0.05) but not vitamin C intake and plasma ascorbic acid. Plasma retinol showed significant correlation with income (rho=0.24), education (rho=0.27), and environment (rho=0.21; rho=0.0001). Similar correlations with plasma ascorbic acid were 0.29, 031, -0.23 respectively (P=0.0001). Logistic regression showed education, environment, green leafy vegetables (GLV) and milk intake as predictors of plasma retinol deficiency, while non-sweet fruit intake, education and passive smoking for plasma ascorbic acid deficiency (P<0.05). CONCLUSIONS: Subnormal status of retinol and vitamin C emphasizes the need to increase consumption of fruit, GLV and milk products, and also better education and environment. Avoiding passive smoking demands attention in order to improve levels of these vitamins. SPONSORSHIP: Department of Science and Technology, India (project no. SP/SO/B39/94).

In vitro dialyzability using meal approach as an index for zinc and iron absorption in humans.

With a standardized protocol under simulated gastrointestinal conditions, 65Zn and 59Fe dialyzability was measured for 38 diets from 7 different published studies on human absorption. The compositions of these diets were available in the form of the amounts of food ingredients used for breakfast, lunch, and dinner. Considering each of these types as a separate meal, percent dialyzability was measured. The weighted average of breakfast, lunch, dinner, and snacks, if any, was taken to represent the entire day's bioavailability. The correlation between in vitro percent dialyzability and reported human absorption was 0.92 for zinc and 0.96 for iron and both were statistically significant (p = 0.0001). The prediction equations for zinc and iron were obtained as y = -0.7718 + 1.1038x and y = 0.3197 + 0.9084x, respectively. This indicated that in vitro dialyzability using the meal approach can be used as an index with good discriminating power for different levels of human absorption.

Comparative performance of pearl millet- and sorghum- based diets vs. wheat- and rice-based diets for trace metal bioavailability.

Pearl millet and sorghum offer a cheap source of energy compared to wheat and rice and are widely consumed by rural communities in many parts of the world. Due to the low consumption of vegetables and animal foods, millets also are the major suppliers of micronutrients especially for low-income groups. It is of prime importance to study how millets perform in terms of bioavailable contents of trace metals. Investigations were carried out using weanling mice which offer a model for the initial testing of bioavailability of trace metals before human trials. Four isocaloric diets differing only in the type of cereal, i.e. pearl millet, sorghum, wheat and rice, were prepared representing habitual dietary patterns observed by National Nutrition Monitoring Bureau (NNMB) of India. Mice were allocated randomly to 4 groups of 8 mice each, and housed individually in metal free metabolic cages. A fifth group of 8 mice fed a balanced synthetic diet served as control. All the groups were fed ad libitum. The absorption of zinc and iron averaged for 3 periods of 5 days each was significantly higher for the wheat and pearl millet group than for the other 2 experimental groups (p < 0.05), as were also the levels of liver zinc and iron. The weight gain was also highest (6.9 +/- 1.2 g) in the pearl millet group as compared to sorghum (1.58 +/- 0.59 g), wheat (1.66 +/- 1.27 g) and rice (-0.72 +/- 0.62 g) groups. The levels of liver copper were comparable in all the 5 groups. These results further confirm our earlier in vitro results indicating the superiority of pearl millet but not sorghum in bioavailability of zinc and iron.

Effect of riboflavin supplementation on zinc and iron absorption and growth performance in mice.

Diets prevalent in vegetarian populations using rice and other whole grains as staples with little consumption of yellow vegetables are low in riboflavin. These diets have poor bioavailability of iron and zinc because metals are present as inorganic salts with low solubility. Riboflavin has the capacity to form complexes, and supplementation of riboflavin may result in increased absorption of zinc and iron, thus increasing the cellular transport. Therefore, riboflavin may have direct as well as indirect effects on growth. Using this as the conceptual basis, experiments were conducted on pregnant and lactating mice. Two groups, each of 12 mice (9 females and 3 males), were observed on a low-riboflavin rice-based diet (adequate in all other nutrients), one with and one without supplementation of 10 mg riboflavin/kg diet. There was significant improvement in the growth parameters like percent conception, mean weight gain in pregnancy, mean weight of pups at the age of 21 d, and percentage hemoglobin due to riboflavin supplementation (p < 0.05). Percent zinc absorption, for the low-riboflavin diet, the supplemented diet, and the synthetic control diet were 16.4+/-5.7, 33.7+/-8.9, and 44.6+/-4.0, respectively, indicating the beneficial effect of riboflavin supplementation on iron and zinc utilization.

Effect of nicotinic acid on zinc and iron metabolism.

Nicotinic acid has functional groups capable of forming complexes with trace metals. The present study examines the effect of nicotinic acid supplementation on absorption and utilization of zinc and iron. In vitro zinc uptake by human erythrocytes was studied using blood samples of 10 healthy subjects. It was found that 8 mumoles nicotinic acid or NADP increased 65Zn uptake by 38.9% and 43.1% in fasting, and by 70.9% and 28.1% in postprandial conditions. In animal experiments, nicotinic acid supplementation to finger millet based diet resulted in significant enhancement of percent zinc absorption, liver zinc and growth of weanling mice (P < 0.05). When mice were fed with nicotinic acid-deficient, -adequate and -excess synthetic diets for four weeks it was observed that, in comparison with the nicotinic acid-deficient diet, percent zinc absorption, intestinal zinc, percent haeomoglobin and liver iron increased significantly under nicotinic acid-adequate and -excess conditions. The results obtained suggested that nicotinic acid, in addition to its known effect on growth and metabolism, may be playing an important role in enhancing zinc and iron utilization.

Assessment of pearl millet vs rice based diets for bioavailability of four trace metals.

Cereals including millets are consumed in India as a staple with wide variety of pulses and vegetables in varying proportions. Trace mineral contents of pearl millet are two to ten times higher than that of rice. Comparative performance of pearl millet based (PM) diets as against rice based (RB) diets in terms of trace mineral bioavailability was studied, based on the prevailing dietary patterns in India. In vitro percent dialysability of zinc, iron, copper and manganese under simulated gastrointestinal conditions was considered as indicator of metal bioavailability. Dialysable zinc and iron were estimated using 65 Zn and 59 Fe as tracers, while dialysable copper and manganese were measured by Atomic absorption spectrophotometer for 20 food items and 15 RB and 17 PM diets prepared from these items. Results indicated that percent dialysability of zinc and copper was higher for RB diets than PM diets, while that of iron and manganese were comparable. Total dialysable iron, copper and manganese in PM diet was 2 to 4 times higher than RB diet.

Zinc, copper & iron contents in cooked foods & estimates of their daily intakes in young hostel residents.

Dietary zinc, copper and iron intakes of 19 men and 11 women (aged 18-25 yr) were determined during three periods of five consecutive days each, using, weighment method and atomic absorption analysis of food samples. Daily zinc, copper and iron intakes of men ranged from 13.1 +/- 1.2 to 15.3 +/- 1.4 mg/d, 1.62 +/- 0.15 to 1.84 +/- 0.17 mg/d and 20.5 +/- 2.8 to 29.1 +/- 4.5 mg/d and of women 8.8 +/- 2.0 to 9.0 +/- 1.6, 1.42 +/- 0.23 to 1.69 +/- 0.62, and 10.0 +/- 2.4 to 14.7 +/- 2.6 mg/d respectively. Cereals provided 67.7 per cent of dietary zinc, 47.7 per cent copper and 62 per cent iron in men and 60 per cent of Zn, 44 per cent of Cu and 59 per cent of Fe in women, suggesting lower contribution of cereals to Cu intakes than Zn and Fe. Men had mineral intakes close to the recommended allowances for Indians, whereas the intakes of women were 30 to 60 per cent lower. When expressed as mg/1000 kcal, lower calorie intakes of women were responsible for their low mineral intakes. Intra-individual variation in mineral intakes was higher (18.39%) than that of energy intakes (14-17%) in both men and women. Phytate: Zn molar ratios were > 15 indicating risk of zinc deficiency in these students.

Performance of normal-weight and underweight men with marginal changes in energy intake.

This study compares the continuous response of six underweight (UW) (body mass index [BMI] < 18 kg/m2) and six normal-weight (NW) (20 < BMI < 25) men of similar age to a modest but sustained level of underfeeding and overfeeding. Habitual energy intake over 4 wk, body composition, and basal metabolic rate (BMR) were measured under metabolic-ward conditions. NW subjects were heavier by 9 kg and had 5% more body fat than UW subjects. The average BMR of UW subjects was 7.5% lower than NW subjects in absolute terms and also per kilogram fat-free mass per day but was higher by 8% when expressed per kilogram body weight per day. Three NW and three UW subjects were given a diet with 10% less energy than their habitual intake for 4 wk. They were brought back to the normal level of feeding for another 4 wk. Finally, they were overfed by 10% for 4 wk. This sequence was reversed in the remaining six subjects. Changes in body weight, BMR, and energy balance were assessed. UW subjects showed a quick and vigorous reduction in BMR (13.4%) during the 1st wk of underfeeding compared with NW subjects (8.1%). In the later weeks, the reduction was 8% in UW and 7% in NW subjects. Furthermore, UW subjects showed a tendency to resist a decrease in body weight (mean loss 180 g), unlike NW subjects (mean loss 730 g). With overfeeding, the mean increase in BMR for UW was higher (7.4%) than for NW (5.3%) subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy intake & resting metabolic rate of young Indian men & women.

Energy intake, body weight and resting metabolic rate (RMR) were measured on seven days consecutively, in 20 men and 14 women on ad libitum food intake under free-living conditions. These measurements were repeated in 8 men and 9 women twice with an interval of two months. Mean energy intake (EI) as measured by 'Weightment' method, was 2820 +/- 577 kcal/d in men and 1611 +/- 147 kcal/d in women. EI showed significant differences between weeks (P less than 0.01, CV = 13.1% in men and 9.5% in women) and between subjects (P less than 0.05, CV = 13.7% in men and 9.8% in women). Intra individual variance contributed up to 60 to 70 per cent of the total variance in EI in both the groups. RMR measured by using Oxylog, varied between the three periods (CV = 6% in men and 5.9% in women) and between subjects (CV = 5.7% in men and 12.3% in women). Mean RMR of both men and women was lower than the predicted value by FAO/WHO/UNU equation. Estimate of mean 24 h energy expenditure, using activity diary and factorial method, in the first round was 2458 +/- 144 kcal in men and 1655 +/- 172 in women, resulting in an energy balance of 308 kcal in men and -44 kcal/d in women. The pattern of activity remained the same in the three rounds for both groups. There were no significant changes in weight (CV-1.6%) or per cent body fat during the study period (P greater than 0.1).