After discovering that vitamin E acts as an antioxidant it was assumed that it can help prevent several chronic illnesses. Studies have arrived at the conclusion that a higher vitamin E intake significantly reduces the risk of cardiovascular deseases. (1,2) Researchers aimed at finding an answer to whether vitamin E can assist in cancer prevention as well, however, the answers turned out to be rather mixed and controversial. This might seem odd at first but taking a closer look at the studies can shed light on many aspects. 

Vitamin E is beneficial, but supplementing it is harmful? 

The controversial results can be demonstrated by two large studies, SELECT (3, 4) and ATBC. (5, 6)  

SELECT observed the effects of vitamin E and selenium in terms of prostate cancer risk. In this study 400 IU alpha-tocopherol was used which is twenty times more than the recommended daily dose. It is also much more than what is possible to consume in the form of natural foods. 

In ATBC 50 mg alpha-tocopherol was used which corresponds to 100 international units. It’s much closer to a realistic, natural intake, but still considerably more that what a healthy diet provides. 

It’s also important to underline that in both studies the participants were typically only given alpha-tocopherol because the researchers beleived it is exclusively responsible for vitamin E’s antioxidant effects. This means that the vitamin E supplement observed in the studies contained nearly one hundred times the amount of alpha-tocopherol found in a healthy diet and almost none of the other tocopherols.  

Surprising results 

The result of the SELECT study showed that vitamin E supplementation increased the risk of prostate cancer by 17%. This result wasn’t observed in the case of the other group where selenium was also supplemented. It’s noteworthy that most participants were diagnosed with early stage prostate cancer, their diagnosis made using the PSA test. However, prostate cancer diagnosed with this type of test often doesn’t develop further. 

In the ATBC study where smoking men were observed vitamin E supplementation decreased the risk of prostate cancer by 32% and of death by 41%. (6) 

There can be several reasons for these contradictory results. It’s possible that vitamin E is more effective in the case of increased oxidative stress caused by smoking. It’s also imaginable that while vitamin E functions as an antioxidant in a natural dosage, if oversupplemented it can increase oxidative stress similarly to other antioxidants. This theory is verified by the other ingredient, beta carotene which also has several beneficial effects, but only if obtained from food. Supplementig beta carotene in an overly large dose and synthetic form increased the risk of lung cancer in the same study. 

Some more interesting facts 

Analysis of the data from the ATBC study 30 years later revealed that the higher a participant’s alpha-tocopherol level was, the lower risk they had of chronic illnesses. (7) In contrast, supplementing alpha-tocopherol had no significant effect on these illnesses in most studies.  

The case of gamma-tocopherol is equally interesting. Many of its anti-inflammatory and anti cancer qualities have been verified using animal models and cell cultures, a relatively new study presented an astonishing result: those with a higher level of gamma-tocopherol had a higher rate of illness and death. (8)  

What’s the explanation for these controversial findings? 

Vitamin E supplementation didn’t show positive results in most studies probably because it was administered in an unnaturally large dosage and as synthetic dl-alpha-tocopherol, not in a mixed form as it is present in natural foods. In this way, overly large dose alpha-tocopherol reduces the level of the other tocopherols which can upset their ratio. (9) 

In the study that claimed that a higher gamma-tocopherol level results in higher mortality researchers believe that gamma-tocopherol levels increase with inflammatory processes. As a consequence – even though gamma-tocopherol itself is indeed of antiphlogistic, antioxidant and protective effect – in the case of severe illness its level increases. 

It counts where it comes from 

Since the gamma-tocopherol intake of the Americans observed came mainly from soy oil and other vegetetable oils rich in omega 6 they made more harm than good. No matter how beneficial vitamin E is, it is important to provide its intake from sources that don’t contain too much polyunsaturated omega 6 or omega 3 fatty acids since vitamin E provides protection mainly against lipidperoxidation generated by them. During lipidperoxidation the unsaturated fatty acids’ double bonds react with oxygen which results in cell damage in the body. What’s more, it initiates a chain reaction through which more free radicals are generated. Vitamin E protects mainly against this and this is the explanation for most of its benefits. 

So the best way to supplement vitamin E is to consume it in natural form and dose as a product that contains mixed tocopherols and tocotrienols and not a high amount of polyunsaturated fatty acid.