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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.

Sup­ple­ment

Recent Evi­dence

DHEA

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.