Vitamin C Boosts Activity of Vitamin E in CF
Study findings suggest it may ease oxidative stress
Vitamin C supplements can increase how long vitamin E stays active in the body in people with cystic fibrosis (CF), a small study suggests.
“It would seem to be clinically prudent for CF clinicians and nutritionists to recognize the importance of dietary and supplemental vitamin C levels and their possible impact on [vitamin E] kinetics in their patients who are undernourished and/or experiencing severe exacerbations of their CF [respiratory] inflammatory disease,” the researchers wrote.
The study, “[Alpha]-Tocopherol Pharmacokinetics in Adults with Cystic Fibrosis: Benefits of Supplemental Vitamin C Administration,” was published in the journal Nutrients.
Oxidative stress is a type of cellular damage induced by oxygen-containing molecules that react with cellular structures, damaging them in the process. Inflammatory conditions generally lead to an uptick in oxidative stress, and CF is commonly marked by inflammation.
Antioxidants are substances that can prevent or lessen oxidative stress. Vitamin E is an antioxidant that is absorbed in fat — and notably, many people with CF have impaired fat absorption due to pancreatic insufficiency.
“In addition to oxidative stress, cystic fibrosis is also characterized by problems with fat absorption, which limits uptake of vitamin E,” Maret Traber, PhD, professor emeritus at Oregon State University and lead author of the study, said in a press release. “Low vitamin E levels plus high oxidative stress is a recipe for more inflammation, which can contribute to a range of negative health outcomes.”
Previous studies done in laboratory models and in smokers have suggested that vitamin C can participate in a biochemical process that “recycles” vitamin E, helping it retain its antioxidative properties for longer. The aim of this study was to test whether this phenomenon also occurs in people with CF.
The study enrolled six adults with CF, ages 23 to 31. All participants had moderate-to-severe lung disease, and all had pancreatic insufficiency managed with standard therapies. One patient was diabetic.
At the start of the study, participants ate a standardized breakfast containing 30% calories from fat, and they took a supplement containing 50 mg each of two forms of vitamin E labeled with a molecular tracer. Blood samples were collected before breakfast and at 3, 6, 9, 12, 24, 36, 48 and 72 hours after taking the supplement, and vitamin E levels were monitored.
Participants repeated this procedure after 3.5 weeks of vitamin C supplementation at a dose of 1,000 mg per day.
“This study used vitamin C far in excess of what someone can easily obtain from the diet. One thousand milligrams is the equivalent of 15 oranges or four or five medium bell peppers,” Traber said.
Both before and after vitamin C supplementation, absorption of vitamin E was similar; levels of the vitamin in the blood reached a peak around 18 to 20 hours after taking the initial supplement. However, the decline in vitamin E levels was markedly slower after vitamin C supplementation.
“Since vitamin E is hanging around longer, it might be able to get into tissues better, and better protect cell membranes from oxidative stress,” Traber said.
Based on these findings, the researchers stated that “a prospective study to determine whether vitamin C supplementation in CF would be beneficial … should be considered.”
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