Potravní doplňky a fortifikace s vitamínem E
Tocopherol esters
Alpha-tocopheryl acetate
- More resistant to oxidation during storage than unesterified tocopherols
- Succinate or acetate moieties are removed from alpha-tocopherol in the intestine
- Bioavailability of alpha-tocopherol is equivalent to that of free alpha-tocopherol
- Main esterified forms of vitamin E in nutritional supplements [10]
Alpha-Tocopheryl succinate
- More resistant to oxidation during storage than unesterified tocopherols
- Succinate or acetate moieties are removed from alpha-tocopherol in the intestine
- Bioavailability of alpha-tocopherol is equivalent to that of free alpha-tocopherol
- Main esterified forms of vitamin E in nutritional supplements [10]
- Could inhibit proliferation and induce apoptosis in a number of cancer cell lines
- Limited data from animal models of cancer
- Administered by injection inhibited tumor growth
- Currently no evidence in humans that taking oral alpha-tocopheryl succinate supplements delivers alpha-tocopheryl succinate to tissues [10]
Alpha-Tocopheryl nicotinate
- Alpha-tocopherol ester
- From synthetic alpha-tocopherol and nicotinic acid (niacin)
- Can be prescribed as a lipid-lowering agent in Europe and Japan
- Marketed as a supplement only in the US [10]
Alpha-Tocopheryl phosphates (Ester-E®)
- No published evidence that supplements containing alpha-tocopheryl phosphates are
- More efficiently absorbed
- Have greater bioavailability in humans than those containing alpha-tocopherol [10]
Gamma-tocopherol
Mixed tocopherols
- Amounts of alpha- and gamma-tocopherol in mixed tocopherol supplements vary [10]
Tocotrienols
- Are also commercially available [10]
V produktech
Natural vitamin E (RRR-alpha-tocopherol) containing supplements:
- IU of RRR-alpha-tocopherol x 0.67 = mg of RRR-alpha-tocopherol
- Example: 100 IU of natural vitamin E provides 67 mg of RRR-alpha-tocopherol [10]
Synthetic vitamin E (all-rac-alpha-tocopherol) containing supplements:
- IU of all-rac-alpha-tocopherol x 0.45 = mg of RRR-alpha-tocopherol
- Example: 100 IU of synthetic vitamin E provides 45 mg of RRR-alpha-tocopherol [10]
Vitamin E-fortified foods
- Often contain synthetic alpha-tocopherol
- Amounts of vitamin E are provided as a percentage of the daily value (DV) of 30 IU (approximately 20 mg of RRR-alpha-tocopherol) [10]
Commercially available forms of alpha-tocopherol
- Synthetic RRR-alpha-tocopherol = all-rac-alpha-tocopherol
- Equal proportions the eight stereoisomers of alpha-tocopherol
- RRR-, RRS-, RSR-, RSS- and their enantiomers SSS-, SSR-, SRS-, SRR- and their esterified forms [2]
- 2R-alpha-tocopherol stereoisomers (i.e. RRR-, RRS-, RSR-, RSS-) only were found to meet human requirements for the vitamin (Weiser and Vecchi, 1982; IOM, 2000)
- 2S-stereoisomers (i.e. SSS-, SSR-, SRS-, SRR-) present in all-rac-alpha-tocopherol possess low affinity for alpha-TTP
- Are rapidly metabolised in the liver (Acuff et al., 1994; Hosomi et al., 1997; Kiyose et al., 1997; Burton et al., 1998) [2]
- Only RRR-alpha-tocopherol is considered to be the physiologically active vitamer [2]
- Natural RRR-alpha-tocopherol (formerly d-alpha-tocopherol)
- By chemical methylation of by-products of soy oil production
- Contains in equal proportions the eight stereoisomers of alpha-tocopherol
- RRR-, RRS-, RSR-, RSS- and their enantiomers SSS-, SSR-, SRS-, SRR-
- Is called all-rac-alpha-tocopherol (formerly dl-alpha-tocopherol)
- Esterified forms (e.g. RRR-alpha-tocopheryl acetate, all-rac-alpha-tocopheryl acetate) [2]
- Bioactivity of each stereoisomer of alpha-tocopheryl acetate has been determined using the resorption–gestation test in the rat (Weiser and Vecchi, 1982)
- Ranges from 21 % for the SSR isomer
- To 90 % for the RRS isomer
- Compared with RRR-alpha-tocopheryl acetate [2]
