The findings, published in the journal Nutrients, are important because more than 160 000 people worldwide suffer from cystic fibrosis, which is characterised by lung inflammation and airway-blocking mucous build-up.
The life-shortening condition is associated with persistent lung infection and afflicts 40 000 people in the US. About 1 000 new cases are diagnosed in the US every year, most in patients aged two or younger.
Unfortunately, the true number of people living with cystic fibrosis (CF) in SA is unknown. “Based on Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) carrier frequency rates of studies dating back to 1999, estimates of cystic fibrosis incidence in Caucasian, mixed race, and black African populations are 1 in 3000 (carrier frequency 1 in 23), 1 in 10 300 (carrier frequency 1 in 55) and 1 in 784-13 924 (carrier frequency 1 in 14 to 1 in 59 live births), respectively. A national survey in 2016 reported nearly 56 million people in SA, of which the majority (45 million) were black Africans and 4.5 million Caucasian. By extrapolation, the estimated number of children born with cystic fibrosis in the same generation would have been 3 214 black Africans and 1 500 Caucasians. There appears to be a significant discrepancy in population estimates and documented number of people with cystic fibrosis in all ancestries, especially black Africans,” according to Zampoli et al. in Cystic fibrosis in South Africa: spectrum of disease and determinants of outcome published online on ERJ Open Research.
Despite steady advances in alleviating complications, the median life expectancy of cystic fibrosis patients is still just 40 years.
“Cystic fibrosis is a genetic disease that is associated with increased inflammation, and like many inflammatory diseases, it comes with a large amount of oxidative stress,” said Maret Traber of OSU’s Linus Pauling Institute, who led the study.
Oxidative stress happens because of an imbalance in the body between free radicals, which can cause harmful chemical reactions, and antioxidants. Antioxidants are molecules able to give an electron to a free radical, causing the free radical to become less reactive without becoming unstable themselves.
“In addition to oxidative stress, cystic fibrosis is also characterised by problems with fat absorption, which limits uptake of vitamin E, a fat-soluble antioxidant,” said Traber, a professor in the Oregon State College of Public Health and Human Sciences. “Low vitamin E levels plus high oxidative stress is a recipe for more inflammation, which can contribute to a range of negative health outcomes.”
Patients’ difficulties with fat absorption mean that they need to consume larger than usual amounts of fat-soluble vitamins like vitamin E, Traber said. Patients need at least 400 milligrams of vitamin E daily to achieve normal blood concentrations, she said.
In this study, the researchers looked at whether vitamin C supplements could help patients better use their absorbed vitamin E. Vitamin C can recycle oxidized forms of vitamin E, and it is also helpful at tamping down the oxidative stress aspects of inflammation, Traber said.
After 3½ weeks of daily 1 000-milligram doses of vitamin C, the patients in the study trended toward lower blood concentrations of a key oxidative stress biomarker, malondialdehyde or MDA, and also toward a slowdown in vitamin E elimination from the bloodstream.
“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.
The benefits of the findings, published in the journal Nutrients, are not unique to cystic fibrosis patients, she noted. Smokers, for example, typically have problems associated with oxidative stress and can benefit from extra vitamin C and possibly extra vitamin E. Metabolic syndrome patients have issues with vitamin C and E as well.