The use of vitamin E supplements in the prevention and treatment of Alzheimer’s disease has been studied for a long time and still controversial: The scientific literature contains contradictory reports on positive and negative results of vitamin E (for an overview of the study situation regarding vitamin E and Alzheimer’s disease, please see the KsD page – Vitamin E)
It is already known that oxidative stress plays an important role in neurodegeneration and that is no doubts about the powerful antioxidant effect of vitamin E. This fact has sparked interest as a potential option for Alzheimer’s patients.
But some differences between vitamin E supplements – which contain mostly alfa-tocopherol – and food sources of vitamin E has been shown, leading to new researches about other components of vitamin E, like gamma tocopherol and tocotrienols.
The term “vitamin E” refers to a group of eight fat-soluble compounds that occur naturally in certain foods and consist of four tocopherols and four tocotrienols, each of which has an alpha, beta, gamma and omega isoform. Of the eight isoforms of vitamin E, our bodies absorb alpha-tocopherol most efficiently, which is why it is the most studied form and the most commonly found in commercially available vitamin E supplements. (info box)
However, it was noticed in the studies that there are some differences between the effects of vitamin E supplements, which usually contain mainly alpha-tocopherol, and vitamin E sources as they occur naturally in food. This fact prompted new research on other components of vitamin E, such as gamma-tocopherol and the spectrum of tocotrienols (see infobox).
Alpha- tocopherol is a potent antioxidant, able to eliminate free radicals such as reactive oxygen species and hydrogen peroxide. It also influences cell signaling and the switching off of those genes involved in the development of Alzheimer’s disease.
Due to controversial findings in previous studies about vitamin E – some showed beneficial effects in delaying cognitive decline and protecting against Alzheimer’s disease and some other didn’t show any benefits – it has been postulated that other forms of vitamin E may play an important whole in protecting the brain from oxidative stress.
The creator of the Mind diet, Dr. Martha Clare Morris, has also emphasized that the use of vitamin E-rich foods may improve cognitive performance in dementia patients and their consumption should be encouraged. In her studies, she found that the highest the amount of vitamin E from food sources, the slowest the cognitive decline in people over 65 years. - you can find a video about that in our Media Library.
A new in vitro study has now addressed precisely this question: Here, the researchers compared the effects of alpha- and gamma-tocopherol in cellular Alzheimer’s model systems and obtained interesting results that provide further information about the effects of vitamin E and its various components.
In this study, special cells with mutations in Alzheimer’s genes were used, which, like the Alzheimer’s brain, form amyloid beta proteins that are components of Alzheimer’s-specific plaques. These “Alzheimer’s cells” were exposed to different concentrations of alpha- and gamma-tocopherol. The impressive result was that both forms of vitamin E were able to reduce the amount of amyloid beta compared to the untreated control but this reduction was more pronounced in the gamma-tocopherol treated cells compared to the alpha-tocopherol treatment. The authors further found that gamma tocopherol was a more potent than the alpha form in improving mitochondrial function and preventing apoptosis (programmed cell death). As we already know, mitochondria are the energy suppliers of every cell. Their function is impaired by the presence of beta-amyloids in early stages of the disease and thus mitochondrial dysfunction leads to neurodegeneration and brain cell death.
Despite many limitations due to the highly simplified test system, this study provides further evidence for the antioxidant and preventive function of various vitamin E components in Alzheimer’s disease. It confirms that the consumption of foods rich in this vitamin complex should always be encouraged. Furthermore, she also emphasizes the need to explore in further clinical studies dietary supplements containing different forms of vitamin E in order to adequately evaluate their efficacy.
What this study has demonstrated:
- Compared to alpha tocopherol, gamma tocopherol has lower bioavailability (is not so good absorbed) but a higher antioxidant effect.
- Gamma-tocopherol is able to reduce oxidative stress triggered by reactive nitrogen species. This so-called nitrosative stress is caused by free radicals, which are of a different nature than the known reactive oxygen species (nitrosative stress or abbreviated “nitro-stress” refers to the excessive formation of nitric oxide (nitrogen monoxide) and its intermediates peroxinitrite and nitrotryosine in metabolism).
- Gamma tocopherol is more effective in reducing beta amyloid from brain cells than alpha tocopherol
- Gamma tocopherol improved mitochondrial function (the “cell power station”) and inhibited apoptosis
- Other forms of vitamin E have good antioxidant effects and should be taken to account in future studies.
Vitamin E is a powerful antioxidant and has therefore long been studied as a promising supplement for the treatment and prevention of Alzheimer’s disease. However, many studies show different and contradictory results. One of the main reasons for this confusion is believed to be the use of supplements that contain only one form of vitamin E: alpha-tocopherol. A recent study has shown that another vitamin E component, gamma-tocopherol, is more effective than alpha-tocopherol, not only in terms of antioxidant activity, but also by improving mitochondrial function and reducing beta-amyloid deposits that lead to Alzheimer’s-specific plaques.
These data already reinforce that the best way to enjoy the benefits of this micronutrient is to eat a diet rich in vitamin E. However, it would also be important to conduct new studies using a combination of different isoforms of vitamin E so that its benefits as a dietary supplement for Alzheimer’s patients can finally be properly evaluated.
Pahrudin Arrozi A, Shukri SNS, Wan Ngah WZ, Mohd Yusof YA, Ahmad Damanhuri MH, Jaafar F, Makpol S. Comparative Effects of Alpha- and Gamma-Tocopherol on Mitochondrial Functions in Alzheimer’s Disease In Vitro Model. Sci Rep. 2020 Jun 2;10(1):8962. doi: 10.1038/s41598-020-65570-4. PMID: 32488024; PMCID: PMC7265356.