Vitamin E Conversion and Recommended Dosage

Conversion Factors

The National Institutes of Health recommends that for vitamin E, 1 IU equals 0.67 mg of natural vitamin E (d-α-tocopherol) or 0.45 mg of synthetic vitamin E (dl-α-tocopherol) 1, 2, 3
Natural vitamin E (RRR-α-tocopherol or d-α-tocopherol): 1 IU = 0.67 mg 1, 2
Synthetic vitamin E (all-rac-α-tocopherol or dl-α-tocopherol): 1 IU = 0.45 mg 1, 2
For IV multivitamin preparations: 1 IU = 1 mg = 1 USP unit dl-α-tocopheryl acetate 1, 2

The National Academy of Sciences recommends a Recommended Dietary Allowance (RDA) of 15 mg/day for individuals ≥14 years 4, 5
The National Academy of Sciences estimates an Average Requirement of 12 mg/day for individuals ≥14 years 4, 5
No distinction is made between adult age categories or between sexes in the current recommendations 4, 5

For infants and children below 11 years receiving parenteral nutrition: ≤11 mg/day 1, 2
For preterm infants: 2.8-3.5 mg/kg/day, not exceeding 11 mg/day 1, 2

α-Tocopherol is the most abundant form in diet and plasma, and the most biologically active form 4, 5
Vitamin E supplements are primarily made from α-tocopherol, often as synthetic dl-α-tocopherol or dl-α-tocopheryl acetate 4, 5

For accurate assessment of vitamin E status, especially in individuals with abnormal lipid levels, the ratio between serum vitamin E and total serum lipids should be used 1, 3
Deficiency is indicated by a serum vitamin E/total lipid ratio <0.8 mg/g of total lipids 3

Over 60% of adults in the United States have vitamin E intakes below the Estimated Average Requirement (<12 mg/d) 4, 5
Vitamin E was characterized as a "shortfall" nutrient by the 2015 Dietary Guidelines Advisory Committee 4, 5

In older adults, intake above currently recommended levels may improve immune and inflammatory responses and reduce risk of infectious disease 4, 5

For preterm infants receiving parenteral nutrition, the recommended daily intake is 2.8-3.5 mg/kg/day, not exceeding 11 mg/day, according to Clinical Nutrition guidelines 6
For children below 11 years receiving parenteral nutrition, the recommended daily intake is ≤11 mg/day, as suggested by Clinical Nutrition guidelines 6
Doses ≤400 IU/day (180 mg/day) appear to have no effect on all-cause mortality, based on evidence from Advances in Nutrition 7
The Tolerable Upper Limit for vitamin E is 1000 mg/day (approximately 1500 IU/day) of any form of supplementary α-tocopherol, as stated in Advances in Nutrition 7

Older adults may benefit from vitamin E supplementation at doses of approximately 200 IU/day (90 mg/day) to improve immune function, according to Advances in Nutrition guidelines 7

The European Society for Clinical Nutrition and Metabolism (ESPEN) recommends a daily intake of 15 mg of alpha-tocopherol during pregnancy 8, 9, 10
The estimated average requirement (EAR) is 12 mg/day for adults, including pregnant women 8, 9, 10
During lactation, the recommended daily intake increases to 19 mg/day 8, 9, 10
The absorption of vitamin E is improved when consumed with fat 8, 9, 10
Supplementation may be appropriate in women with fat malabsorption (inflammatory bowel disease, cystic fibrosis) 8, 10
The American Diabetes Association recommends considering supplementation as part of a standard prenatal multivitamin, not as a high-dose isolated supplement 11
The National Institutes of Health recommends measuring alpha-tocopherol serum levels via HPLC if deficiency is suspected or supplementation is considered 8, 9
Expressing results as the vitamin E/total lipids ratio (deficiency defined as <0.8 mg/g total lipids) is recommended 8, 9
Samples must be processed with care to avoid oxidative degradation 8, 9
Deficiency of vitamin E is rare in healthy pregnant women with a balanced diet [8, 10] [8, 9, 10]