HERBAL "SMART DRUGS"
The so-called smart drugs may win the contest for
ingenious marketing of marginally effective agents. Their
popularity has been fueled in part by the
general enthusiasm for cleansing and lack of intoxication in a drug-weary culture. The recent explosion of
"energy" drinks shows little sign of abating. Although taking a drug to improve mental quickness instead of
getting bombed certainly seems innocent, nowhere is superstition more rampant than in the marketing claims for drugs that
improve memory and general mental
acuity. There is truly a desperate need for such drugs in medicine to
retard the memory loss caused by Alzheimer's disease and some other forms of
dementia. However, despite years of effort, only a few marginally
effective drugs have been developed (this is discussed in the "Nicotine
chapter).
The herbal smart
drugs are often a concoction of various amino acids
and similar
compounds. The most common supplements in energy drinks and herbal
"smart" supplements are the sulfur-containing amino acid taurine, carnitine, and precursors to neurotransmitters
including tyrosine, phenylalanine,
and choline. Should you take "smart" nutrients? First, if you are eating a normal American diet with the typical
excess of protein,
Let's look at a couple of examples. Phenylalanine
is reputed to have marvelous
pleasurable qualities as the precursor to dopamine. There is some truth to this claim. Tyrosine and phenylalanine
are both amino acids that are required for the synthesis of proteins. Tyrosine
is the basic building block for the
neurotransmitters dopamine and norepinephrine, and it is logical to think that
increasing tyrosine might improve mood. However, the average American eats enough protein to provide adequate levels of these amino acids. Taking a pharmacologic (big)
dose of tyrosine may be able to boost
catecholamine production for a short time, but the benefits are transient, and scientists are just starting to
study the behavioral outcomes (if
any) of supplementing tyrosine.
There may be more truth to the claims that taking
large doses of other neurotransmitter
precursors can influence the production of the neurotransmitter. Choline supplements can indeed
enhance the production of the
neurotransmitter acetylcholine, which is important for many aspects of brain function, including memory. The
death of acetylcholine neurons may
contribute to the disabling memory loss of Alzheimer's disease, and supplementing acetylcholine production
can produce slight and temporary
improvement in the memory of Alzheimer's patients. The choline precursor citicoline actually may improve
memory a bit in both healthy people and
those who have experienced brain injury and Alzheimer's disease, but whether
the effect is large enough to overcome the disease process remains to be seen. Similarly, the
tryptophan in high-protein foods like
milk can enhance the production of serotonin in the brain. Because increases in serotonin are speculated to
enhance sleep, there may be some truth
to the old wives' tale that warm milk enhances sleep. Another claim that might have some credibility is that
ingesting extra tryptophan could help
to prevent the loss of serotonin that occurs when a person takes Ecstasy. There
is a rapid loss of serotonin in this case, which perhaps can be
Taurine and carnitine
are the most common additions to energy drinks. Taurine is a sulfur-containing amino acid and is very abundant in the
body, including in the brain, and it
seems important for maintaining many body functions including blood pressure and metabolism. It may function as an inhibitory neuromodulator, especially in
situations like ischemia or stroke where
it may counteract the release of excitatory neurotransmitters. Studies in animals seemed to indicate it was a panacea—it lowered blood pressure, improved glucose tolerance in diabetes, possesses
valuable antioxidant properties, and
best of all, burns fat. Unfortunately, human studies are fewer, but they offer sonic opposing concerns—it
may raise blood pressure in women,
does not burn fat, and lowers glucose unless rats also eat fructose (or presumably people drink soft drinks).
Clearly, more work is needed to
understand the benefits and risks of taurine supplementation. Similarly, carnitine is also an important normal constituent
of the body that is necessary for
the production of energy by mitochondria, and a lack of carnitine caused by a genetic deficiency can have extremely adverse effects on brain function. There are some published studies of
carnitine supplements in various
neural disorders including Alzheimer's disease and Parkinson's disease with mixed results at best. Does this mean that giving dietary supplements to healthy young adults improves
memory? Again, we have no evidence,
and many compounds that show
marginal effects in impaired populations
have even less action in healthy adults. So will these "energy" drinks give you a better edge mentally in studying
for exams? Perhaps, but the reason may be the 100 to 280 milligrams of
caffeine that they contain! Many other
"nutraceuticals" including SAMe (S-adenosylmethionine) and various vitamins often appear in supplements
and benefit people who are
deficient—not normal, well-nourished adults.
Nevertheless, hope springs eternal that we will find the natural product to optimize
mental function or stave off the effects
of aging. The findings that
resveratrol, a molecule present in red wine,
prolongs life and improves functioning in aging mice led to another wave of hope until we learned that the amounts required equal the resveratrol in 750 to 1,500 bottles of
wine a day!
