Garlic (Allium sativum) is no longer just useful for preventing attacks by vampires. Recent research suggests that this herb might be useful for slowing or preventing the onset of Alzheimer's disease (AD). Over the past decade more and more evidence has suggested that genes alone to do not lead to AD. It is now clear that many environmental factors such as diet, lifestyle, head injuries, obesity, educational level, exposure to heavy metals or pesticides may play major roles. Thus, it's not surprising that researchers are discovering that certain aspects of our diet may significantly increase or decrease the probability of developing AD.

Garlic has been recommended for many different diseases, including high blood pressure, elevated levels of lipids in the blood, and diabetes. Unfortunately, garlic treatments induce many unpleasant side effects including irritation of the stomach and intestines, nausea, vomiting, diarrhea and anemia due to increased bleeding. Many of these side-effects are made worse by also taking over-the-counter pain medications such as aspirin and ibuprofen. These side effects indicate that garlic contains some quite powerful chemicals that can have both positive and negative effects upon health. The principle chemical culprit is allicin and a variety of related allylsuphides.

One way to avoid the nasty effects of taking garlic is to age it. Aged garlic extract (AGE, which is a wonderfully appropriate acronym) can be prepared by soaking garlic slices in a water-ethanol mixture for 20 months. This soaking process removes most of the offending compounds and leaves one very useful compound behind, S-allyl-L-cysteine. How does this chemical helps us? The answer begins by discussing the two most influential things we do that ages us: eating and breathing.

The food we eat must be metabolized, a process that requires the oxygen in the air we breathe. We acquire energy by breaking down the carbon bonds found in fats, sugars, and proteins and then gobbling as much energy from the process as possible. This process leaves our cells with left-over carbon atoms that are combined with oxygen and expelled as carbon dioxide. [Mosquitoes find us by sensing expelled carbon dioxide; once they do, they suck the blood from our bodies - just like vampires.]

Because oxygen is also exceedingly toxic to cells, it must be utilized very carefully. Indeed, scientists have recently discovered that the genes that control energy metabolism have been highly conserved across millions of years of evolution, from yeast to humans, and that these genes influence the rate of the aging process. Essentially, the better we negotiate our food-oxygen exchange, the longer and healthier we live. Disrupt the balance in this exchange and the impact can be harmful to the brain.

With normal aging, because we insist on eating and breathing, tissue-damaging molecules called oxygen-free radicals are formed in our bodies. Free radicals are not always harmful; however, they become more prevalent with age and may slowly overwhelm our natural anti-oxidant systems, destroying our neurons and just about every other cell in our body. It turns out that each species' maximum lifespan may be determined by how many free radicals are produced.

This is where garlic extracts come to the rescue; they appear to protect our neurons from free radicals. Garlic is not a cure for AD. However, today the focus of much research is on finding ways to slow the progression of AD or delay its onset entirely. The savings to our national health bill would be enormous if we could simply delay being diagnosed with AD for only two additional years. Aged garlic's ability to reduce obesity, lower blood pressure and control hyperglycemia, which are all risk factors for developing AD, certainly make future investigations of AGE very worthwhile. Bram Stoker might have been a true visionary.

© Gary L. Wenk, Ph.D., author of Your Brain on Food (Oxford, 2010)

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