Research Summary

Wright, Jonathan et al.
A Human Clinical Study of Ester-C® vs. L-Ascorbate Acid. 1987.

A small study in 12 adults. Participants were placed on a low vitamin C diet for 1 week and then received either ascorbic acid or Ester-C®, 3000mg. White blood cell (WBC) ascorbate levels were measured before Vit C and at 4,8 and 24 hours after. Urinary ascorbate levels and oxylate levels were also analysed. Ester-C® showed: less urinary oxylate output, less vitamin C loss in the urine and higher WBC levels than were seen with regular ascorbic acid.

Verlangieri, Anthony.
Acute study to determine the Relative Rate of Absorption and Excretion of U.S.P. Calcium Ascorbate and Ester-C® Calcium Ascorbate. 1988.

A study comparing Ester-C® Calcium Ascorbate to U.S.P. (United States Pharmacopoeia) Calcium Ascorbate determined that the structure of Ester-C® is unique and differs from USP Calcium Ascorbate. This study discussed how Ester-C® is absorbed more rapidly than Calcium Ascorbate.

Bernal, S. et al.
Vitamin C uptake in White Blood Cells in Vivo. 2006.

Bernal, S. et al: comparison of white blood cell levels of ascorbate after oral use of 1000mg of either Ester-C® or regular ascorbic acid. 3 groups of 5 people (15 subjects total, all adult men ages 21-50) received one of the vitamin C preparations or placebo, followed by a washout period of 6 days and then were given one of the other treatments until they had been tested in all 3 groups. After taking supplements, blood samples were collected at 1,2,3,4,8 and 24 hours. Vitamin C levels were determined in plasma and WBC. There was no significant difference in the uptake of different forms of vitamin C into plasma or WBC; however, there was a difference in the retention of vitamin C WBC. Ester-C® was retained in WBCs longer than regular ascorbic acid and this was apparent 24hr after administration.

Van Straten, M et al.
Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled survey.
Advances in Therapy. 19(3): May-Jun: 151-9. 2002.

A larger study (186 participants) received Ester-C® or placebo for 60 days during the cold and flu season (Nov-Feb) 1000mg once a day with their main meal. There were fewer upper respiratory tract infections over the study in the Ester-C® vs. the placebo group (37 vs. 50). In addition, in those who did become ill, symptoms were less severe and lasted, on average, a day less in the Ester-C® group. Also, 16 people with infections in the placebo group developed a second infection during the trial, whereas this happened in only 2 cases in the Ester-C® group. Conclusion - Ester-C® resulted in fewer respiratory tract infections and those who did get sick recovered faster and were much less likely to develop a second respiratory infection vs. placebo.

Gruenwald, J. et al.
Safety and Tolerance of Ester-C® compared with regular ascorbic acid.
Advances in Therapy. 23(1): Jan-Feb: 171-8. 2006.

A study in people with stomachs sensitive to acidic foods to determine tolerability of Ester-C® vs. regular ascorbic acid (AA). 50 study participants received either Ester-C® or AA for 3 days, followed by a 1-day washout period (received neither treatment) then 3 days of the opposite treatment for comparison. Of the GI side effects reported (mostly stomach discomfort). A total of 28 people reported epigastric discomfort, 62.5% of these were in the AA group. The prevalence of epigastric adverse effects was 66% higher in AA than Ester-C® group. Severity of adverse effect was greater in AA than Ester-C® group as well for those who complained of epigastric problems associated with treatment.