Insulin resistance and adiposity in relation to serum β-carotene levels.

Canas JA, Damaso L, Altomare A, Killen K, Hossain J, Balagopal PB; Feb. 2012


The aim of this study was to measure the effects of nutritional counselling and an encapsulated fruit and vegetable juice powder concentrate (FV) versus nutritional counselling alone on levels of beta-carotene and retinol, adiposity, inflammation, and insulin resistance in overweight and lean boys.


Thirty-nine prepubescent boys (aged 6 to 10) were recruited to participate in this double-blind, placebo-controlled study. Thirty completed the study; of these, 21 were overweight and 9 were lean. All the boys received a 1-hour nutritional counselling session at baseline, which was reinforced after 3 months. The boys were randomized to take either an encapsulated fruit and vegetable juice powder concentrate (Juice Plus+®) or placebo for 6 months. Their beta-carotene and retinol levels were measured along with various markers of inflammation and metabolic health, including abdominal fat mass.  


Six months of supplementation with FV in combination with nutritional counselling raised beta-carotene levels in both lean and overweight boys but did not affect retinol or retinol-binding protein. None of the participating children experienced significant weight loss; however, abdominal fat mass decreased significantly in the treatment group while it increased in the placebo group. Among overweight boys, FV improved insulin resistance and decreased triglycerides. Because the improvement in insulin resistance occurred without a concurrent rise in retinol, the researchers speculated that beta-carotene may play a more important role than retinol in metabolic gene regulation and is a promising potential marker of insulin sensitivity and nutritional status.


A 6-month supplementation with FV in the presence of nutritional counselling was associated with an increase in serum beta-carotene concentrations and a reduction in adiposity in conjunction with an improvement in insulin resistance in overweight boys.

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