3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-benzopyran-6-ol

Additional toxicological data

Administrative data

Endpoint:

additional toxicological information

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientifically valid review

Data source

Reference

Reference 1

Reference Type:

review article or handbook

Title:

TOLERABLE UPPER INTAKE LEVELS FOR VITAMINS AND MINERALS

Author:

Scientific Committee on Food Scientific Panel on Dietetic Products, Nutrition and Allergies

Year:

2006

Report date:

2006

Reference 2

Reference Type:

review article or handbook

Title:

Scientific opinion on the safety and efficacy of vitamin E as a feed additive for all animal species.

Author:

EFSA (FEEDAP)

Year:

2010

Bibliographic source:

EFSA Journal, 2010, 8(6), 1635

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Vitamin E

EC Number:

215-798-8

EC Name:

Vitamin E

Cas Number:

1406-18-4

IUPAC Name:

2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)chroman-6-ol

Applicant's summary and conclusion

Conclusions:

Absorption and metabolism
The bioavailability of vitamin E (tocopherols) is related to the efficiency of absorption. Intestinal absorption of lipids and fat-soluble vitamins depends on pancreatic function, biliary secretion to form micelles with the hydrolysed fat, and transfer across intestinal membranes. Nearly all of the vitamin E absorbed across the intestinal mucosa is free tocopherol. In vivo and in vitro studies suggest that the rate of uptake of vitamin E is controlled by passive diffusion. Absorption of tocopherols is incomplete; the extent of absorption is dependent on intake and varies between 20-80%. The proportion absorbed decreases with increasing amount added to experimental diets; the average absorption is about 40-60% while pharmacological doses of 200 mg and more are absorbed to the extent of <10%. Cannulation studies indicate that there is no difference in absorption between α-tocopherol and α-tocopheryl acetate at physiological doses. At high levels of intake, (> 400 IU/day) a higher degree of absorption was obtained with free tocopherol than tocopheryl esters. About 90% of the free α-tocopherol is transported via the lymphatic system into the bloodstream,where it is distributed into lipoproteins on passage into the liver.

Executive summary:

Absorption and metabolism of Vitamin E

The bioavailability of vitamin E is related to the efficiency of absorption. Intestinal absorption of lipids and fat-soluble vitamins depends on pancreatic function, biliary secretion to form micelles with the hydrolysed fat, and transfer across intestinal membranes. Nearly all of the vitamin E absorbed across the intestinal mucosa is free tocopherol. In vivo and in vitro studies suggest that the rate of uptake of vitamin E is controlled by passive diffusion. Absorption of tocopherols is incomplete; the extent of absorption is dependent on intake and varies between 20-80%. The proportion absorbed decreases with increasing amount added to experimental diets; the average absorption is about 40-60% while pharmacological doses of 200 mg and more are absorbed to the extent of <10%. Cannulation studies indicate that there is no difference in absorption between α-tocopherol and α-tocopheryl acetate at physiological doses. At high levels of intake, (> 400 IU/day) a higher degree of absorption was obtained with free tocopherol than tocopheryl esters. About 90% of the free α-tocopherol is transported via the lymphatic system into the bloodstream,where it is distributed into lipoproteins on passage into the liver. The main systemic transport system of tocopherols is the LDL-fraction (55-65%) followed by the HDL (24-27%) and VLDL (8-18%). There is very close correlation (r=0.925) between the total serum α-tocopherol and that portion carried by LDL.

Tocopherol is excreted as a water soluble conjugated compound resulting from different oxidation steps.