Micronutrient supplementation improves physical performance measures in Asian Indian school-age children.

Micronutrients are important in physical work capacity and therefore performance. The impact of a multi-micronutrient-fortified nutritional beverage on physical performance measures among clinically healthy school-age children was assessed in a double-blind (for test and placebo groups), placebo-controlled, randomized trial in children aged between 7 and 10.5 y (n = 300). The participants with height- and weight-for-age Z-scores between 0 and ≥ -3 were randomized to 1 of 3 study arms: fortified choco-malt beverage powder (F), matched energy equivalent unfortified placebo (U), and untreated control (C). Participants in the F and C groups were given 40 g fortified (19 key vitamins and minerals) and unfortified choco-malt beverage, respectively, daily for 120 d. Primary efficacy outcomes included endurance and aerobic capacity using a 20-m shuttle test and step test. Other physical performance measures included speed (40-m sprint), visual reaction time, maximal hand grip, and forearm static endurance. Micronutrient status included thiamin, riboflavin, folate, niacin, iron, pyridoxal phosphate, and vitamins B-12 and C. All measurements were made at baseline and the end of the intervention. There was a within-subject increase in aerobic capacity and whole body endurance (P < 0.05) accompanied by a significant improvement in the status of iron thiamin, riboflavin, pyridoxal phosphate, folate, and vitamins C and B-12 in the F group compared to the within-subject changes in the other 2 groups (P < 0.05). The study suggests that multiple micronutrient supplementation in similar populations may be beneficial in improving micronutrient status and enhancing aerobic capacity and endurance in children.

Vitamin B12 deficiency & levels of metabolites in an apparently normal urban south Indian elderly population.

BACKGROUND & OBJECTIVES: There is no published literature on the extent of vitamin B12 deficiency in elderly Indians as determined by plasma vitamin B12 levels and methylmalonic acid (MMA) levels. Vitamin B12 deficiency is expected to be higher in elderly Indians due to vegetarianism, varied socio-economic strata and high prevalence of Helicobacter pylori infection. We therefore, studied the dietary habits of south Indian urban elderly population and measured vitamin B12, MMA red cell folate and homocysteine (Hcy) levels. METHODS: Healthy elderly urban subjects (175, >60 yr) were recruited. Detailed history, physical examination and neurological assessment were carried out. Food Frequency Questionnaire (FFQ) for dietary analysis for daily intake of calories, vitamin B12, folate and detailed psychological assessment for cognitive functions was carried out. Blood samples were analyzed for routine haematology and biochemistry, vitamin B12, red cell folate, MMA and Hcy. RESULTS: The mean age of the study population was 66.3 yr. Median values for daily dietary intake of vitamin B12 and folate were 2.4 and 349.2 µg/day respectively. Sixty two (35%) participants consumed multivitamin supplements. Plasma vitamin B12 level and the dietary intake of vitamin B12 was significantly correlated (P=0.157). Plasma vitamin B12 and Hcy were inversely correlated (P= -0.509). Red cell folate was inversely correlated with Hcy (P= -0.550). Significant negative correlation was observed between plasma vitamin B12 and MMA in the entire study population (P= -0.220). Subjects consuming vitamin supplements (n=62) had significantly higher plasma vitamin B12 levels, lower MMA levels and lower Hcy levels. There was no significant correlation between plasma vitamin B12, MMA, Hcy and red cell folate and any of the 10 cognitive tests including Hindi Mental Status Examination (HMSE). INTERPRETATION & CONCLUSIONS: Our study is indicative of higher vitamin B12 (2.4 µg/day) intakes in urban south Indian population. Thirty five per cent of the study population consumed multivitamin supplements and therefore, low plasma vitamin B12 levels were seen only in 16 per cent of the study subjects. However, MMA was elevated in 55 per cent and Hcy in 13 per cent of the subjects.

Limited predictive ability of surrogate indices of insulin sensitivity/resistance in Asian-Indian men.

Insulin resistance is highly prevalent in Asian Indians and contributes to worldwide public health problems, including diabetes and related disorders. Surrogate measurements of insulin sensitivity/resistance are used frequently to study Asian Indians, but these are not formally validated in this population. In this study, we compared the ability of simple surrogate indices to accurately predict insulin sensitivity as determined by the reference glucose clamp method. In this cross-sectional study of Asian-Indian men (n = 70), we used a calibration model to assess the ability of simple surrogate indices for insulin sensitivity [quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment (HOMA2-IR), fasting insulin-to-glucose ratio (FIGR), and fasting insulin (FI)] to predict an insulin sensitivity index derived from the reference glucose clamp method (SI(Clamp)). Predictive accuracy was assessed by both root mean squared error (RMSE) of prediction as well as leave-one-out cross-validation-type RMSE of prediction (CVPE). QUICKI, FIGR, and FI, but not HOMA2-IR, had modest linear correlations with SI(Clamp) (QUICKI: r = 0.36; FIGR: r = -0.36; FI: r = -0.27; P < 0.05). No significant differences were noted among CVPE or RMSE from any of the surrogate indices when compared with QUICKI. Surrogate measurements of insulin sensitivity/resistance such as QUICKI, FIGR, and FI are easily obtainable in large clinical studies, but these may only be useful as secondary outcome measurements in assessing insulin sensitivity/resistance in clinical studies of Asian Indians.

A pilot study on hyperinsulinaemic euglycaemic clamp based insulin sensitivity in young adult Indian males with low body mass index.

BACKGROUND & OBJECTIVE: Indians have decreased insulin sensitivity (IS) and a greater adiposity at a lower body mass index (BMI) when compared with other ethnic groups. Despite this, IS has not been studied in Indians of low BMI. This study thus used the hyperinsulinaemic euglycaemic clamp (HEC) technique to compare IS in young normal weight (NW) and low BMI (LBMI) Indian males. Clamp IS was also compared with convenient indices of insulin sensitivity such as the homeostatic model assessment (HOMA). In the NW group, clamp IS was compared with published data of similarly measured IS in other studies and ethnic groups. METHODS: Ten NW [body mass index (BMI): 18.5-25 kg/m(2)] and ten LBMI (BMI < 18.5 kg/m(2)) young healthy Indian males aged between 19-32 yr were recruited through advertisements from Bangalore slums. Fasting plasma glucose and insulin, glucose disposal rates (GDR) and IS were the parameters measured during the HEC technique. RESULTS: The NW group had a Clamp IS of 4.5 (3.8, 5.3) (median, lower, upper quartile, mg/(kg x min)/microU/ml) that was close to half that of the LBMI group; 9.9 (7.1, 13.4: P<0.001). Clamp IS in the NW group was significantly lower than that observed in published studies involving other ethnic groups (P<0.05). Clamp IS and per cent body fat (% BF), were significantly and negatively correlated (n = 20, rho = -0.7, P<0.001). Correlations between Clamp IS and other IS indices ranged from rho = -0.5 for HOMA2-%B to rho = 0.5 for HOMA2-%S (P<0.05); however, the correlation with HOMA1-IR was not significant (rho = 0.4). INTERPRETATION & CONCLUSION: The significantly lower Clamp IS of the NW group compared with the LBMI group and other ethnic groups indicated that IS was impaired in Indians at relatively low BMIs. Most of the convenient indices of IS were significantly correlated with Clamp IS, however, the Clamp IS was more sensitive method with greater discriminatory power, since IS differences between LBMI and NW groups were only apparent with Clamp IS.

Effects of animal source food and micronutrient fortification in complementary food products on body composition, iron status, and linear growth: a randomized trial in Cambodia.

BACKGROUND: Poor nutritional quality of complementary foods often limits growth. Animal source foods, such as milk or meat, are often unaffordable. Local affordable alternatives are needed. OBJECTIVE: We evaluate the efficacy of 2 newly developed, rice-based complementary food products: WinFood (WF) with small fish and edible spiders and WinFood-Lite (WF-L) fortified with small fish, against 2 existing fortified corn-soy blend products, CSB+ (purely plant based) and CSB++ (8% dried skimmed milk). DESIGN: In total, 419 infants aged 6 mo were enrolled in this randomized, single-blinded study for 9 mo, designed primarily to assess increments in fat-free mass by a deuterium dilution technique and change in plasma ferritin and soluble transferrin receptor. Secondary endpoints were changes in anthropometric variables, including knee-heel length. Data were analyzed by the intention-to-treat approach. RESULTS: There was no difference in fat-free mass increment in WF or WF-L compared with CSB+ [WF: +0.04 kg (95% CI: -0.20, 0.28 kg); WF-L: +0.14 kg (95% CI: -0.10, 0.38 kg)] or CSB++ [WF: -0.03 kg (95% CI: -0.27, 0.21 kg); WF-L: +0.07 kg (95% CI: -0.18, 0.31 kg)] and no effect on iron status. The 1.7-mm (95% CI: -0.1, 3.5 mm) greater increase in knee-heel length in WF-L than in CSB+ was not significant. CONCLUSIONS: No difference was found between the locally produced products (WF and WF-L) and the CSBs. Micronutrient fortification may be necessary, and small fish may be an affordable alternative to milk to improve complementary foods. The dietary role of edible spiders needs to be further explored. This trial was registered at controlled-trials.com as ISRCTN19918531.

The effect of a controlled 8-week metabolic ward based lysine supplementation on muscle function, insulin sensitivity and leucine kinetics in young men.

BACKGROUND & AIMS: The 2007 FAO/WHO/UNU lysine requirement is 30 mgkg(-1)d(-1). Developing country populations may be at risk of lysine deficiency, with effects on muscle and its function. The effect of an 8 wk lysine supplementation diet on muscle mass and function was assessed. METHODS: Healthy, under and well-nourished men were studied before and after 8 wk, during which low (n=20) and high (n=20) lysine diets were consumed. The low lysine diets (∼25 and ∼40 mgkg(-1)d(-1) for under and well-nourished respectively) were based on the subjects' habitual lysine intake, while the high lysine diet supplied 80 mgkg(-1)d(-1). Anthropometry, muscle function, insulin sensitivity (IS) and leucine kinetics were measured before and after the experimental period. RESULTS: The high lysine diet had a small positive effect (about +7.5%) on muscle strength, but no effect on other parameters. Over the 8 wk period in the whole group, the change in muscle strength correlated with the change in muscle mass (r=0.5, P=0.001), while the change in muscle mass correlated with the change in IS (r=0.3, P=0.04), but there were no intake specific differences. CONCLUSION: Over an 8 wk controlled feeding period, an intake of 80 mg lysine kg(-1)d(-1) had a small positive effect on muscle strength, but no other effects.

Cardiac autonomic responses to hyperinsulinemia are associated with skeletal muscle function in healthy human subjects.

Hyperinsulinemia related to obesity may result in activation of the sympathetic nervous system (SNS). Acute autonomic responsiveness to insulin is influenced by body composition, particularly obesity. However, it is unclear whether skeletal muscle mass or function determines autonomic responsiveness to insulin. While muscle function is associated with insulin sensitivity, there are no studies that have assessed if skeletal muscle function modulates autonomic responses to hyperinsulinemia. Fifty healthy men (aged 18-35years) were evaluated for skeletal muscle function (hand grip strength and static and dynamic endurance) and then divided into low and high endurance (LE and HE) groups. Heart rate variability (HRV) in the frequency domain was measured during a hyperinsulinemic euglycemic clamp (HEC). With hyperinsulinemia, the HE group had a higher increment in total power of HRV (1615+/-2536 vs. 97+/-1943, P=0.08) and normalized low frequency (LF) HRV (16.2+/-17.9 vs. -1.3+/-14.8, P=0.008) as compared to the LE group. A significant reduction in the normalized high frequency (HF) HRV was seen in the HE group but not in the LE group (-12.3+/-12.9 vs. 1.7+/-13.9, P=0.009); this translated into an increase in LF/HF ratio for the HE group and but not the LE group (1.21+/-1.8 vs. -0.08+/-0.65, P=0.016). The present study indicates that there are differential cardiac autonomic responses to hyperinsulinemia in healthy human subjects with variable skeletal muscle function.