A single dose of Ester-C resulted in significantly higher retention of vitamin C in white blood cells, which would support cellular concentrations for a range of functions, including immunity, according to findings published in SpringerPlus.
“[Ester-C] significantly increased leukocyte vitamin C levels compared to [ascorbic acid] and [placebo],” wrote the researchers. “This may be due to the metabolites in [Ester-C], which have been shown to facilitate absorption and enhance retention. The superior bioavailability of [Ester-C] in leukocytes may be beneficial to overall immune function since intracellular vitamin C levels are vital to the fundamental process of leukocytes.”
Ester-C contains calcium ascorbate plus small amounts of vitamin C metabolites, including dehydroascorbate, calcium threonate, and 4-hydroxy-5-methyl-3(2H)-furanone. It was originally sold as a branded ingredient when NBTY acquired it in 2006. It was then relaunched as a branded supplement in 2007.
John Frame, VP of marketing for Ester-C welcomed the study’s findings. “Ester-C is the only product of its kind on the market, and customers can easily find it by the ’24-Hour Immune Support’ call out on the label,” he said. “This product has been clinically studied to stay in the white blood cells longer than regular Vitamin-C -- a distinct advantage to anyone looking to nutritionally support their immune system all day long.”
Led by Dr Susan Mitmesser, Sr. director of nutrition & scientific affairs at NBTY, the researchers recruited 30 healthy, non-smoking subjects aged between 18 and 60 to participate in their double-blind, placebo-controlled, crossover trial. The participants were randomly assigned to receive a single dose of placebo (0 mg vitamin C), ascorbic acid (1000 mg vitamin C), and Ester-C (1000 mg vitamin C), preceded by a 7-day washout period.
Both Ester C and ascorbic acid significantly increased plasma vitamin C levels, compared to placebo, and there were no differences between the vitamin C groups, which supported the bioavailability of both sources.
However, vitamin C levels in leukocytes, which are reflective of tissue stores and influences on immune function, were significantly higher at eight and 24 hours compared with regular ascorbic acid. On the other hand, no significant increases in leukocyte vitamin C levels were observed for ascorbic acid or placebo (see figure below).
“This study is a great example of the commitment NBTY has to scientific diligence around our product innovations,” said Dr Mitmesser. “As new ingredients and areas of research emerge, our scientific leadership will continue to be a priority and a differentiator in the scientific community and the supplement market with NBTY products leading the way.”
2016 5:1161, doi: 10.1186/s40064-016-2605-7
“Determination of plasma and leukocyte vitamin C concentrations in a randomized, double-blind, placebo-controlled trial with Ester-C”
Authors: S.H. Mitmesser, Q. Ye, M. Evans, M. Combs