engleski

How much vitamin E is enough?

Patients with cystic fibrosis (CF) have significantly decreased plasma levels of vit. E, an antioxidant, due to fat malabsorption and chronic pulmonary inflammation. Recommendations for vitamin supplementation vary widely. from 50 – 400 U/day. Our patients are advised to take 200 U/day. The aim of this study was to evaluate the efficacy of this supplementation dose. 17 children taking 200 U/day of vitamin E for at least 6 months have been investigated (10 girls, 7 boys ; mean age: 3 years, range 9 months -23 years, all PI and on enzyme therapy). The mean plasma vitamin E concentration was low: 4.22 + 2.56 mg/L (normal range: 5.8-16.8 mg/L), only 3 children (18%) had values within the normal range. Expressed per gram of total lipid (cholesterol + triglicerides + phospholipids), which is a better indicator of stores, the mean vitamin E:lipid ratio was 1.19 + 0.66 mg/g, i.e. above the reported lower limit of normal, with 71% of patients (12 out of 17) within the normal range. No patient developed values above normal for vitamins. In order to compare usefulness of different supplemental doses on vitamin E status for the same individuals, a subgroup of 10 subjects that formerly took 100 U vit. E daily were additionally studied. Mean plasma vitamin E level and mean vit.E:lipid ratio on different supplementation doses was compared using Student’ s t test. Results are as follows (for 100 U/day and 200 U/day, resp.): mean plasma vitamin E level was 2.86 + 0.91 mg/l and 4.69 + 1.93 mg/l ; mean vit.E:lipid ratio was 0.83 + 0.34 mg/g and 1.38 + 0.64 mg/g. Plasma concentration was low in both measurements, but significantly lower while taking 100 U/day (p=0.002). Vit.E:lipid ratio was borderline while on 100 U/day and increased significantly to normal value during 200 U/day supplementation (p=0.002) ; 8 patients out of 10 (80%) reaching normal ratio. We believe these data support our recommendation to start vit. E supplementation with 200 U/day. It is safe and useful for the majority of CF patients, while 100 U/day is insufficient in more than 50% of cases. Nevertheless, ~30% of patients would need a higher dose to reach vit. E normal values, so periodic checkups and individual dose titration is necessary.

Vitamin E; antyoxidans

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