Vitamin E dose recommendations may be too high for Cystic Fibrosis patients, finds new research

Mixed nuts in a bowl

This month’s featured paper is from the British Journal of Nutrition and is entitled 'Vitamin E intake, α-tocopherol levels and pulmonary function in children and adolescents with cystic fibrosis’.  The team,  Janna W. Woestenenk, Nancy Broos, Rebecca K. Stellato, Hubertus G. M. Arets, Cornelis K. van der Ent and Roderick H. J. Houwen, from the University Medical Centre Utrecht, The Netherlands, report on the current Vitamin E recommendations Cystic Fibrosis patients.

Cystic fibrosis (CF) is a life-threating genetic disorder, characterised by chronic pulmonary inflammation that causes a gradual, progressive decline in pulmonary function, partly due to oxidative stress. Most patients have pancreatic insufficiency, leading to intestinal malabsorption of fat and fat-soluble vitamins. Therefore, lifelong treatment with fat-soluble vitamins such as vitamin E has become standard care.

It has been suggested that higher vitamin E levels, expressed as serum α-tocopherol levels, have a protective effect on pulmonary condition in CF. However, serum α-tocopherol levels are compromised during a pulmonary exacerbation and recover with resolution of the inflammation. Likewise, chronic pulmonary inflammation may reduce levels, and the suggested association between vitamin E levels and pulmonary function might be secondary.

Whether current recommendations for vitamin E supplementation are optimal for preventing deficiency and whether higher serum α-tocopherol levels have beneficial effects on pulmonary function are subjects of debate. The present paper studied the association between vitamin E intake (dietary intake plus prescribed supplementation), the coefficient of fat absorption and chronic inflammation on serum α-tocopherol levels, and the long-term effect of both serum α-tocopherol levels and chronic inflammation on pulmonary function in paediatric patients with CF.

Results
In our study sample, we found no clear effect of vitamin E intake, the coefficient of fat absorption or chronic inflammation on serum α-tocopherol levels. Moreover, patients with CF received vitamin E supplementation at half the CF-specific recommended dosage; nevertheless, serum α-tocopherol levels were normal. 
Furthermore, we found that chronic inflammation was inversely associated with pulmonary function and we found no association between serum α-tocopherol levels and pulmonary function. Paradoxically, we even found an overall trend towards a lower pulmonary function in those with higher serum α-tocopherol levels.

Conclusions
Our results suggest that the CF-specific vitamin E recommendations are higher than necessary to prevent deficiencies. Therefore, vitamin E dosages of 50% of the recommendations could be used, at least initially. We found no evidence that higher serum α-tocopherol levels had protective effects on pulmonary function in paediatric patients with CF. Moreover, the finding of higher serum α-tocopherol levels in patients with lower pulmonary function casts doubt on the hypothesis that vitamin E has therapeutic benefits.

Janna W. Woestenenk

View the full paper here