Saturday, April 16, 2011

Vitamin(S!) E, The Whole Picture: Delta Tocopherol a Rising Star in Cancer Protection

Those of you who have attentively followed my dissertation on fish oil (cf. SHR: ProfDrAndro talking on the Pros & Cons of Fish Oil) may remember that - as an aside - I mentioned that not alpha-tocopherol, which is what supplement companies add to their fish oils, but delta-tocopherol would be the anti-oxidant of choice to protect the highly oxidizable oil from going rancid.

Figure 1: Toco-8, one of the few
products on the market
A very recent report (Li. 2011) on findings of scientists from The State University of New Jersey is only one out of a whole line studies that imply that the real health value of "vitamin E" (we should better start writing "the vitamins E") does not lie in one, but in the combination of the tocopherols (alpha, gamma, delta) and the naturally ocuring tocotrienols, of which both the delta-tocopherol, as well as the group of tocotrienols have long been overlooked in the course of what one should probably call the "alpha-tocopherol"-hype.

According to Li et al., of the three tocopherols (alpha, gamma, delta @ a human equivalent dose of 800IU) the scientists fed to mice, which had previously been "infected" with "human lung cancer H1299 cells", the "δ-Tocopherol inhibited tumor growth most strongly" (delta > gamma > alpha). And with reference to the underlying mechanism of the observed superiority of delta-tocopherol to the two other isomers, the scientists argue:
The higher activity of δ-T in the inhibition of tumor growth corresponded well with its ability to inhibit the formation of 8-OHdG, γ-H2AX, and nitrotyrosine as well as to induce cell apoptosis.
With 8-OHdG being a marker for oxidative stress, γ-H2AX being a marker for cellular damage and nitrotyrosine being a reactive derived from nitrogen species and tyrosines in proteins, these findings suggest that delta-tocopherol protects against oxidative stress and cellular damage, and, at the same time, facilitates apoptosis of cancerous cell lines (on a side note: a characteristic feature of cancer is that the "normal" and healthy programmed cell death does not occur). Alpha-tocopherol, on the other hand, has "little or no influence" on these parameters.

If one also takes into consideration that the tocopherols appear to displace each other...
[...] dietary γ- or δ-tocopherol, however, decreased serum α-tocopherol levels, and dietary α-tocopherol decreased serum levels of γ-tocopherol. is becoming more and more obvious that supplementation with isolated tocopherols, as it has been the case in many of the inconsistent studies on the effect of "vitamin E" on cancer, is not warranted.

So, if you decide to copy the study and supplement 800IU of vitamin E, make sure it comes from a source of "natural, mixed tocopherols" or even better tocopherols & tocotrienols, of which S. Wada in a very recent review (Wada. 2011) on the effects of vitamin E on cancer writes:
Vitamin E, especially tocotrienols, seems to be a potent agent for cancer prevention, however no large-scale clinical trial on the cancer prevention effect of tocotrienols has been conducted yet. Therefore it is expected that clinical trials overcoming the lower bioavailability of tocotrienols will be conducted, and it is urgently needed to assess the safety and the efficacy of the administration of the tocotrienols as a part of a cancer prevention regimen.
Ah, and don't forget: The SuppVersity is the place where you will read about these studies first ;-)