BACKGROUND:Maca is a root vegetable that grows high in the Andes in Peru and Bolivia. Legend has it that Inca warriors ate copious quantities of maca before going into battle. While energising them for the battle, it allegedly left them overly virile for the women of the conquered cities.
Whether or not such effects were due to maca, or the general context of war and pillage, references to this legend crop up in current marketing of maca as a sexual enhancement herb. Questions have been raised suggesting that this “legend” may be of very recent origin.
What is more reliably attested to is that maca is a nutritious food that grows where little else will thrive.
Maca (or Lepidium meyenii) grows between 4,000 and 4,500 metres above sea level in intensely cold regions. The whole plant is edible, with the leaves used as a green vegetable. The roots form tubers similar in size and shape to a large radish or small turnip. These are eaten, or used medicinally to prepare an extract that Andean farmers used to enhance fertility in animals – and humans.
As sexual problems have received increased attention in recent years, maca has become one of the most commonly cited natural products said to improve sexual desire and fertility.
EVIDENCE FROM STUDIES
Extracts of maca contain a number of plant sterols, which are compounds similar in chemical structure to steroids. But consuming maca does not appear to significantly change testosterone or oestrogen levels in men or women. This has led researchers to look for other compounds which might impact sexual desire or fertility. Several animal studies found that male rats fed maca had improved sperm production and overcame erectile dysfunction (ED). However, some of these studies used very small numbers of animals and had other weaknesses.
In the last couple of years, four controlled studies of maca have been conducted in humans. One was a randomised, double-blind study involving 50 men with mild ED. After 12 weeks, the group taking maca showed a significant improvement in their symptoms and psychological well-being.
Three controlled trials were conducted with healthy men and women. One found improved sexual function in postmenopausal women. The two others examined the impact of maca on sexual desire in men and one of these found a small but significant increase in desire, while the other found no improvement. But all of these studies were small (involving between eight and 57 subjects) and had other limitations.
Maca plant material has been consumed as a vegetable for centuries without reports of problems but, in the studies above, adverse effects were not examined.
Maca has a long traditional use for sexual health but this refers to its use as a vegetable, not a concentrated extract. A limited amount of research has been conducted on maca extracts. The results of these studies are encouraging and support further investigation. However, as a systematic review of this evidence recently concluded, “the total number of trials, the total sample size, and the average methodological quality of the primary studies were too limited to draw firm conclusions”.
Another caution is warranted with sexual-enhancement herbal remedies. Batches in every part of the world have been found that contain adulterants such as Viagra and similar drugs. This is especially problematic with supplements bought on the internet.
Maca grows in severe climates and is difficult to cultivate, making it likely that unauthentic products will appear on the market.
Until validated and high-quality brands can be readily identified, caution with any herbal sexual enhancement product is warranted.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics. He is a senior lecturer in the School of Nursing and Human Sciences, DCU.