Stereochemistry for Dummies – Why Natural Vitamin E Is Better Than Synthetic
First of all, stereochemistry is not about what music to put on the stereo to set the right mood. In terms of vitamin E, it is simply a matter of distinguishing the right-handed molecule from a mixture containing both left- and right-handed vitamin E. It really is that simple. In terms of handedness in organic structures, the term is used to describe the arrangement of four different functional groups of other atoms around a particular atom of carbon. The right-handed form (designated d- for dextro) and the left-handed form (abbreviated as l-) are called stereoisomers. They are mirror images of each other. While they look identical to each other on paper, the molecules with which they react can certainly tell the difference.
The term vitamin E refers to a group of eight different isomers of a chemical called alpha-tocopherol. Of these, only one isomer is the biologically active form. Vitamin E from natural sources is enriched in this form, whereas synthetic sources of alpha-tocopherol contain a mixture of both, or dl-alpha tocopherol. This means that in order to obtain the same biological effect, a person would have to ingest a greater amount, roughly one-third more, of synthetic vitamin E than they would the same nutrient obtained from natural sources. By using the synthetic form, not only are you consuming things that you don’t really need, you are also paying for them.
Part of the reason for this difference is that natural form of vitamin E is preferentially absorbed by the body compared to its synthetic counterpart. Specific transport and binding proteins that are manufactured in the liver choose the natural d-alpha isomer over all the others. This is not just a test-tube effect. There is empirical evidence to suggest that it is clinically relevant.
In one study, scientists from East Tennessee State University¹ investigated chemically-labeled vitamin E in healthy volunteers and in pregnant women. Subjects were given either 30 milligrams per day or 300 milligrams per day of a mixture contain half of the natural and half of the synthetic vitamin E. In pregnant women, the blood levels of natural vitamin E rose two times as much as the synthetic substance in the non-pregnant volunteers. In umbilical cords, natural form of vitamin E was enriched three-fold compared to vitamin E from synthetic sources.
In separate experiments², researchers in Japan alternately gave synthetic and natural vitamin E to seven young, healthy women. To achieve the same blood levels of the vitamin as those obtained by giving the subjects 100 mg of natural vitamin E, it required 300 mg of synthetic vitamin E.
Observational studies have shown that people with a higher intake of vitamin E were less likely to develop heart disease. Furthermore, vitamin E consumption has been associated with a longer time to institutionalization in people with Alzheimer’s disease.
What does this mean for you?
For best results make sure you take a multivitamin that includes vitamin E from natural sources rather than one of synthetic origin. “How can I tell the difference just by looking at the bottle?” you may wonder. Here is an easy shortcut you can use – natural forms of vitamin E start with the “d-” prefix, while the synthetic forms start with a “dl-”. Give it a try. Get your multivitamin bottle right now and check what type of vitamin E is in it.
¹Acuff RV, Dunworth RG, Webb LW, Lane JR. Transport of Deuterium-Labeled Tocophereols During Pregnancy. Am J Clin Nutr 1998 March; 67(3): 459-464.
²Kiyose C, et al. Biodiscrimination of Alpha-Tocopherol Stereoisomers in Humans After Oral Administration. Am J Clin Nutr 1997 March; 65 (3): 785-789.
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