Maca: Aphrodisiac, Libido and Sperm and Semen Booster
Will Maca (Lepidium meyenii or L. peruvianum) improve erectile dysfunction?
The answer is 'yes, indirectly'. This is one of the few herbs that has
some decent evidence for being a good, old fashioned and legitimate aphrodisiac.
This is a plant that grows
in the high altitudes of the Andes in Peru and has been eaten by the natives for centuries for
both food and increasing sexual potency. And, in this case, it looks like
the natives knew what they were doing: studies on rats and mice have shown
it dramatically improves sexual behaviors. 
In other words, at least in rodents, science has shown that Maca is a powerful aphrodisiac.
What about in humans? Well, even though no studies have been done on
Maca's libido-enhancing powers to date on humans, Maca has been shown to also be
something sent down by the fertility gods. Researchers examining nine men,
aged 24-44, found that "the semen volume, total sperm count, motile sperm count,
and sperm motility (Grades a+b) were significantly increased after treatment
with Maca".  So Maca gives you more sperm, better sperm and more seminal
fluid. And it definitely makes you feel more "full" down there below the belt
and ready to ejaculate!
It's interesting that these men had no statistically significant changes in hormones
such as follicle stimulating hormone, luetinizing hormone, testosterone, estrogen
or prolactin. Somehow, Maca does its thing without significantly altering
hormone levels. However, the researchers did speculate that perhaps Maca changed
levels of free testosterone, which is most critical for us males, without changing
Maca has many other very desireable properties, including improved lipid
profiles, lowering cortisol, aiding in muscle growth, boosting
super-antioxidants and so on. I document
these in my link on the Powerful Effects of Maca.
One other item of interest is whether or not Maca affects androgens.
No study to date has found a statistically significant increase or decrease in
testosterone or other hormones and Maca's actions appear to be in the aphrodisiac
realm. One suspected compound is p-methoxybenzyl isothiocyanate, but this
has not been thoroughly studied.
Maca - Side Effects
Maca has an excellent safety profile and we can
take comfort in the fact that it has been eaten as a food for probably millennia
by the Peruvians and Bolivians. It has been placed fresh on foods by
the natives as well as cooked in various dishes. Peruvians consider it a
food, although they recognize its "medicinal powers" as well. The only
caution that I know regarding Maca is that one study on Maca showed
a moderate increase in blood pressure
at the relatively low dose of just 600 mg/day. 
work with your doctor
whenever trying a new program or supplement.)
I take organic Maca from
Navitas: Navitas Naturals Organic Raw Maca Powder
and have had good results with it. I always cook it, usually through
throwing it in my oatmeal.
Some people have trouble digesting the starch of the maca root, which can lead to
stomach upset, gas and/or diahrrea. If this is an issue for you, you can order the gelatinized
form, which is usually in the human studies by the way: Maca Power - 100% Certified Organic "Gelatinized" Maca.
My understanding is that simple cooking does not break down these starches
sufficiently for those who have trouble, whereas the gelatinized version handles
that for you.
I should also forewarn you that Maca has a strong taste that is completely quite
different from anything else you have probably eaten. I don't find the
flavor objectionable but many people do. For many guys, though, the
benefits far outweigh its strong aftertaste.
CAUTION: Maca is generally one of the most well-received
supplements - although really it could be considered a food like fenugreek -
on the forum and in emails. For example,
this forum poster lists it as his favorite. However, I
did get one forum poster who said that
Maca gave him issues and actually lowered his libido and another that said it lowered his testosterone. You can
read about that here. Maca reportedly
can be stimulating for some and so some men cycle it, i.e. four or five days consuming Maca and
a few days of rest afterwards.
Also, it is worth noting that some supplement manufacturers put Maca and
Horny Goat Weed together in the same capsule taking advantage of their
complementary effects on male physiology. Horny Goat Weed directly boosts
Nitric Oxide and boost libido. Maca, through a complete different pathway,
boosts semen volume and libido. It is a good combination that does work
well for many guys, but you want to get a formulation that has an extract of
Icariin (for the Nitric Oxide) and 500 mg of the Maca.
1) Urology,2000,55:598-602;J Ethnopharmacol,2001,75:225-9
2) Asian J Androl,Dec 2001,3:301-303
3) Food and Chemical Toxicology, Mar 2008, 46(3):1006-1013, "Maca (Lepidium
meyenii) and yacon (Smallanthus sonchifolius) in combination with silymarin as
food supplements: In vivo safety assessment"