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Nutrition and supplements (DHEA, Ginkgo Biloba, Omega‑3): separating myth from fact

How can nutri­tion influ­ence brain func­tions?

Assorted Fruits & VegetablesFirst of all, the brain con­sumes con­sid­er­able amount of glu­cose. One of the ear­li­est sign of demen­tia is a decrease in the abil­i­ty of the brain to use glu­cose effi­cient­ly. As such a dys­func­tion is at the core of dia­betes, some neu­ro­sci­en­tists refer to Alzheimer’s Dis­ease as Type 3 dia­betes.

The brain is also a fat­ty organ. Fats are present in the neu­rons’ mem­branes to keep them flex­i­ble. These fats are the omega 3 and omega 6 fat­ty acids mol­e­cules. Our brain is depen­dent on dietary fat intake to get enough fat­ty acids. Omega‑3 fat­ty acids can be found in cold-water fish (such as mack­er­el, her­ring, salmon, and tuna), kiwi, and wal­nuts. Docosa­hexaenoic acid, or DHA, is the most abun­dant omega‑3 fat­ty acid in cell mem­branes in the brain.

In gen­er­al, the brain is high­ly sus­cep­ti­ble to oxida­tive dam­age. This is why antiox­i­dant food has become pop­u­lar for their pos­i­tive effects on brain func­tion. Antiox­i­dants are found in a vari­ety of food: Alpha lipoic is found in spinach, broc­coli and pota­toes; Vit­a­min E is found in veg­etable oils, nuts, green leafy veg­eta­bles; Vit­a­min C is found in cit­rus fruit and sev­er­al plants and veg­eta­bles. Berries are well known for their antiox­i­dant capac­i­ty but it is not clear which of their many com­po­nents has an effect on cog­ni­tion.

Based on these obser­va­tions, Dr. Lar­ry McCleary (whose inter­view you will find at the end of this Chap­ter) rec­om­mend a diet con­tain­ing fat­ty fish, veg­eta­bles and sal­ads, non-starchy fruits (like berries) — that are high in free rad­i­cal fight­ing com­pounds — and nuts.

As most peo­ple you prob­a­bly have bought or thought of buy­ing nutri­tion com­ple­ments. Indeed it is hard to get all the good nutri­ents in one’s diet. The most com­mon con­sumer pur­chase is herbal and vit­a­min sup­ple­ments pur­port­ed to improve mem­o­ry. Table 2 shows you the most recent find­ings asso­ci­at­ed with well-known sup­ple­ments such as Gink­go bilo­ba.

How­ev­er one has to be cau­tious. One neg­a­tive aspect of self-med­ica­tion with herbal sup­ple­ments is the fact that some prod­ucts have been shown to coun­ter­act the effects of pre­scrip­tion and over-the-counter med­ica­tions. For exam­ple, in 2001, Dr. Piscitel­li from the Nation­al Insti­tute of Health (NIH) showed a sig­nif­i­cant drug inter­ac­tion between St. John’s wort (hyper­icum per­fo­ra­tum), an herbal prod­uct sold as a dietary sup­ple­ment, and Indi­navir, a pro­tease inhibitor used to treat HIV infec­tion. The herb has also caused neg­a­tive inter­ac­tions with can­cer chemother­a­peu­tic drugs and with birth con­trol drugs.

Experts usu­al­ly rec­om­mend a bal­anced diet, that is get­ting healthy nutri­ents (Omega‑3, antiox­i­dants, etc.) from the food you eat, rather than ingest­ing sup­ple­ments. Few stud­ies so far have shown that sup­ple­ments are ben­e­fi­cial to brain health. More impor­tant­ly the best dosage of these sup­ple­ments is not known.


Recent Evi­dence


A steroid pre­cur­sor to testos­terone and estro­gen pur­port­ed to fight aging.

The con­clu­sion of a two year study at the Mayo Clin­ic in Min­neso­ta and Uni­ver­si­ty of Pad­ua in Italy showed that DHEA did not improve strength, phys­i­cal per­for­mance, or oth­er mea­sures of health. The study’s lead author, Dr. Nair (2006) said, “No ben­e­fi­cial effects on qual­i­ty of life were observed. There’s no evi­dence based on this study that DHEA has an anti-aging effect.”
Gink­go bilo­ba

An over-the-counter “mem­o­ry-enhanc­ing” sup­ple­ment.

In 2002 Dr. Paul Solomon from Williams Col­lege found that “when tak­en fol­low­ing the man­u­fac­tur­er’s instruc­tions, gink­go pro­vides no mea­sur­able ben­e­fit in mem­o­ry or relat­ed cog­ni­tive func­tion to adults with healthy cog­ni­tive func­tion.”

Dr. Burns (2006) from the Uni­ver­si­ty of Ade­laide, Aus­tralia found longer-term mem­o­ry improved in healthy fifty-five to sev­en­ty-nine year olds, but no oth­er cog­ni­tive mea­sure improved for younger par­tic­i­pants.

Dr. Elsabagh (2005) from King’s Col­lege Lon­don found that gink­go ini­tial­ly improved atten­tion and mem­o­ry. How­ev­er, there were no ben­e­fits after 6 weeks, sug­gest­ing that a tol­er­ance devel­ops quick­ly.

A recent ran­dom­ized tri­al (DeKosky et al., 2008), con­duct­ed in 5 aca­d­e­m­ic med­ical cen­ters in the Unit­ed States and includ­ing 2587 vol­un­teers aged 75 years or old­er with nor­mal cog­ni­tion, showed that G bilo­ba at 120 mg twice a day was not effec­tive in reduc­ing the over­all inci­dence rate of demen­tia.

Omega‑3 fat­ty acids

Com­po­nents of neu­rons’ mem­branes.

Dr. Fontani’s work at the Uni­ver­si­ty of Siena in Italy asso­ci­at­ed omega‑3 sup­ple­men­ta­tion with improved atten­tion­al and phys­i­o­log­i­cal func­tions, par­tic­u­lar­ly those involv­ing com­plex cor­ti­cal pro­cess­ing.

Table 2. Sum­ma­ry of recent find­ings on sup­pos­ed­ly brain-enhanc­ing dietary sup­ple­ments.

Keep learn­ing by read­ing more arti­cles in the Resources sec­tion, and also please con­sid­er join­ing our free month­ly Brain Fit­ness eNewslet­ter

This new online resource is based on the con­tent from the book The Sharp­Brains Guide to Brain Fit­ness (May 2009, $19.95), by Alvaro Fer­nan­dez and Dr. Elkhonon Gold­berg.

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As seen in The New York Times, The Wall Street Journal, BBC News, CNN, Reuters,  SharpBrains is an independent market research firm tracking how brain science can improve our health and our lives.

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