Peruvian and Andean Medicinal Plants: Maca, Cat's Claw and Others

Plants with a place of origin

Peoples of the Andes and the Amazon have used many plants for food and health. This page covers a few that are now sold worldwide, and it keeps traditional use separate from what has been tested. We describe publicly documented information only. It sits alongside Mexican folk herbs and the curanderismo overview. It does not cover plants used in ceremonies, which are outside the scope of this site; see Psychedelic Therapy for that library. Sourcing and fair trade questions are on sustainability and commercialization of traditional medicine.

Maca

Maca (Lepidium meyenii) is a plant of the cabbage family native to Peru, growing in harsh climates above 4,000 feet. [1] Memorial Sloan Kettering Cancer Center (MSK) says it has been used traditionally to enhance fertility and sexual performance and to relieve menopausal symptoms. [1] Traditional use is not evidence, so here is what trials found:

• Sexual function: a 2010 systematic review found four randomized trials against placebo. Two suggested benefit, one found none in healthy cyclists, and one showed effects in erectile dysfunction. The authors called the evidence limited and the trials too few and too small. [2]
• Menopausal symptoms: a 2011 review found four randomized trials, all favorable, but too few and too small for firm conclusions, and safety "has not been proved yet." [3]
• Semen quality: a 2022 meta-analysis of five randomized trials found unclear and mixed effects, with no significant gain in sperm concentration versus placebo. [4]

Label: promising but limited for sexual function and menopausal symptoms, mixed for semen quality. Safety: MSK says side effects have not been reported, but maca may interfere with lab tests that measure testosterone. Tell your clinician if you took it before blood work. MSK also advises talking with a provider if you have a hormone-sensitive cancer, or are pregnant or breastfeeding. [1] A toxicology review found low acute toxicity in animals and said quality standardization and more clinical research are needed. [5] See adaptogen safety for the wider context.

Cat's claw (uña de gato)

Cat's claw is a woody vine, and NCCIH says Indigenous people of the Amazon rainforest have used it for centuries. [6] NCCIH finds no conclusive evidence from human studies for any health purpose, because many studies were small or not rigorous. [6] Small trials exist: 45 people with knee osteoarthritis took Uncaria guianensis or placebo for four weeks, with less pain on activity, [7] and 40 people with rheumatoid arthritis on standard drugs had a modest drop in tender joint count over 24 weeks. [8] Both were small and brief. Insufficient evidence.

Cautions from NCCIH: cat's claw might make the immune system more active, which could increase symptoms of autoimmune disease; it may slow blood clotting and raise bleeding risk in surgery; and it may interact with blood thinners, antiplatelet and blood pressure drugs. [6] Some studies of its use in pregnancy suggest it is unsafe. [6] A case report described reversible worsening of Parkinson disease symptoms after taking it. [9] See supplements before surgery.

Yacon

Yacon (Smallanthus sonchifolius) is a root rich in fructooligosaccharides, which act as prebiotics. [10] In a crossover trial of 40 women, 40 g of yacon syrup with breakfast lowered glucose at 30 minutes and insulin at 15 to 45 minutes compared with placebo. [10] That is a short, meal-time study, not proof of benefit for diabetes. Promising but limited.

Sangre de drago

A 2003 review of the sap of Croton lechleri reported that lab and animal studies largely supported traditional uses, and that clinical studies reported positive results for traveler's and watery diarrhea and insect bites. It also noted that the sap varies by area and products need standardization. [11] This is an older review, so look for newer evidence and ask a clinician before using any product for diarrhea. Preclinical, with limited clinical evidence.

Product quality and when to seek care

Herbal supplements are not approved by the FDA before sale, and manufacturers are responsible for their own labeling. [6] See how supplements are regulated. Do not use any of these plants instead of medical care for diabetes, arthritis, infection or fertility problems. Call 911 for an emergency, and Poison Help at 1-800-222-1222 for a suspected poisoning.