Remember Your Vitamin E
Before I did my Master’s degree, I had an impeccable memory. Dates, times, phone numbers, chemical processes and Latin names for anatomical parts were pretty easy.
My brother even once challenged me to memorize a list of 20 random items in 20 minutes — no problem. But that was BM, before my Master’s.
After my Master’s, my memory was never the same. Was it age? Maybe. But more likely it was stress and lack of proper nutrition.
Yup, memory, stress, and the food you eat are related.
Stress — of any kind — causes chemical stress in the body. Chemical stress includes the production of free radicals, aka reactive oxygen species, aka little molecular critters floating around rusting out your cells. (More on this below.)
Alzheimer’s disease has been linked to this oxidative damage. Antioxidants, found in food, seem to protect your body from free radical damage. One of those chemicals with antioxidant properties is vitamin E.
Vitamin E
Vitamin E is a fat-soluble vitamin (like vitamins A, D & K). Again, it’s an antioxidant (like vitamin C and β-carotene), and essential for neurological function.
You can find vitamin E in vegetable oils, nuts, green leafy vegetables, avocados, seeds, whole grains, tomatoes, apples and carrots.
You probably think of vitamin E as a singular thing. In fact, there is a whole family of vitamin Es. Four tocopherols (α, β, γ and δ) and four tocotrienols (α, β, γ and δ) make up the vitamin E family.
α-tocopherol is the family member that your body has most of, and that absorbs best. Since α-tocopherol is the only vitamin E family member found in blood (the plasma), scientists have done the most research on it (and generally people are more willing to give a blood sample than, say, a muscle biopsy).
But even though α-tocopherol is found in the highest amount in the body, it isn’t the best at counteracting free radicals; γ-tocopherol has the highest anti-oxidative capacity.
What are free radicals?
Every once and awhile you hear about a new superfood that’s high in antioxidants. Great! But why are antioxidants good?
Well antioxidants fight free radicals! Great… what are free radicals?
No, free radicals aren’t an unstable indie rock band or a fringe political group; they’re molecules. Free radicals are chemically unstable and very chemically reactive, which causes damage to your body… until your friendly neighbourhood antioxidant comes along and stops the chemical carnage caused by free radicals.
Geek Alert!What causes the chemical damage is the free radicals stabilizing themselves. If you remember your high school chemistry, then you might remember that electrons are arranged by shells. Electrons in each shell like being in pairs; when they aren’t paired up they try really hard to find another electron. Free radicals stabilize by giving or taking electrons (atomic sub-particles) from other molecules because they don’t have paired outer shells of electrons. This causes the new molecule to become a free radical too. That is, until an antioxidant like vitamin E breaks the chain. |
Where do free radicals come from?
Well, they don’t sneak in in the middle of the night. They can come from both outside and inside the body.
- External sources: Exposure to tobacco smoke, UV rays, pollution, radiation, ozone, and pesticides causes free radicals to be made in your body.
- Internal sources: Your body can trigger the making of free radicals too. Yup, the evil problem-causing free radicals can come from you in the course of normal metabolic or daily functions, such as:
- exercising
- using your mitochondria
- using your phagocytes (white blood cells that chew up debris) — in other words, having an immune system challenge
- having inflammation
- stress
Research question
This week’s review examines a study that looks at the relationship between the antioxidant vitamin E and risk of Alzheimer’s. Could high levels of vitamin E in your blood reduce your risk of Alzheimer’s?
Mangialasche F, et al. High plasma levels of vitamin E forms and reduced Alzheimer’s disease risk in advanced age. J Alzheimers Dis. 2010;20(4):1029-37.
Methods
The scientists wanted to figure out if having low or high blood levels of vitamin E (all versions) could be correlated with Alzheimer’s disease in people over 80 years old.
Since this study was done in Sweden, the 232 participants were from Sweden. Researchers analyzed their blood for vitamin E, and then followed for up to 6 years to see if they ended up with Alzheimer’s disease. Pretty simple.
Results
Age
After all the analysis was done the researchers found that the people who had Alzheimer’s were slightly older (86.2 years old on average) than the ones that didn’t have it (84.6 years old on average).
Vitamin E
When doing a straight comparison between the people who ended up getting Alzheimer’s and those who didn’t, there was no difference in the blood levels of any of the vitamin E isomers.
Of all the isomers, only low blood levels of β-tocopherol could possibly be related to Alzheimer’s. I say possibly because statistically the results are inconclusive (for those interested, p=0.055 comparing β-tocopherol in control and Alzheimer’s cases).
To try to make things a bit clearer– and/or if you’re a skeptic — to have a more publishable paper, the scientists did another type of analysis: they compared the 25% of the people with the highest vitamin E levels with the 25% of the people with the lowest vitamin E levels and looked at how often each group got Alzheimer’s.
This second analysis did show something interesting:
People in the high vitamin E group for tocopherols (all four α-δ) were less likely to have Alzheimer’s than people in the low tocopherol group. Same results for tocotrienols and total vitamin E (all isomers).
So while in general, a straight comparison didn’t show much of a link, being in the top 25% for every isomer of vitamin E meant you were less likely to have Alzheimer’s.
Conclusion
This study is different than most studies looking at vitamin E and Alzheimer’s disease, because it looks at all eight isomers of vitamin E. Most studies only look at α-tocopherol, since it’s the most abundant.
From this study it seems that having high levels of all versions of vitamin E in your blood reduces your risk of getting Alzheimer’s disease by between 45-54%.
A few downsides to this study:
- There weren’t that many people in it (only 232); it was over a pretty short period of time (6 years); and they didn’t look at how much vitamin E everybody was eating.
- Having more participants would give the study stronger statistical power — in stats more people is better.
- Because the study duration was only 6 years it’s possible that there were people with undiagnosed Alzheimer’s in the control group.
- By not knowing how much vitamin E people ate, we don’t know if pre-Alzheimer’s causes a drop in vitamin E or if less vitamin E triggers Alzheimer`s. In other words we don’t know if the vitamin E is a cause, correlation, or effect.
Bottom line
Even though this study shows a link between vitamin E and Alzheimer’s, we don’t know whether eating more vitamin E will prevent Alzheimer’s.
So before you start chowing down vitamin E supplements (especially ones that are just a single isomer), simply add a little more nuts, seeds (and fresh/cold-pressed nut/seed oils), green leafy vegetables, avocados, whole grains, tomatoes, apples, and carrots to your diet.
And spit out that cigarette!
References
- Sayre LM, Perry G, Smith MA.Oxidative stress and neurotoxicity. Chem Res Toxicol. 2008 Jan;21(1):172-88.
- Monastero R, Mangialasche F, Camarda C, Ercolani S, Camarda R. A systematic review of neuropsychiatric symptoms in mild cognitive impairment. J Alzheimers Dis. 2009;18(1):11-30. Review
- Burton GW, Traber MG. Vitamin E: antioxidant activity, biokinetics, and bioavailability. Annu Rev Nutr. 1990;10:357-82. Review.