Human Studies
Yellow Maca
While yellow maca accounts for the largest percentage (47%) of maca distribution, the evidence on yellow maca is limited. The research suggests that yellow maca supports:
-
Musculoskeletal health
-
Reproductive health in males and females
Below is a compilation of the available human studies for yellow maca with a comprehensive overview of the study details provided.
Effect of three different cultivars of Lepidium meyenii (Maca) on learning and depression in ovariectomized mice
About the Study
Type of study: Animal study, 21 days
Population: 3-month-old, ovariectomized mice, Swiss strain
Aim of the study: To assess the effect of yellow, red, and black maca on cognitive function and depression in ovariectomized (OVX) mice
Maca Details
Species: Lepidium meyenii
Source of maca: Not stated
Location where maca was grown: Carhuamayo, Junín
Agricultural methods used: not stated
Part of maca used: Hypocotyls
Form of maca: Aqueous extract of yellow, red, and black maca
Dose: 1g/kg BW/day, oral administration
Outcomes
Results:
Black maca provided the most beneficial effects on latent learning, as measured by water finding task, particularly on trained mice though all phenotypes were effective for trained and non-trained mice (p<0.05)
The immobility time measured in the forced swimming test was decreased in the groups treated with the three colors of maca (yellow, red and black), suggesting is anti-depressant effects.
Other details:
The three colors of maca increased uterine weight of OVX mice, suggesting it is due to progestin-like effects.
Effect of chronic treatment with three varieties of Lepidium meyenii (Maca) on reproductive parameters and DNA quantification in adult male rats
About the Study
Type of study: Animal study, 84 days
Population: 3-month-old adult male rats, Holtzman strain
Aim of the study: To determine whether treatment with diverse varieties of maca (red, yellow, and black) affects daily sperm production (DSP), sperm counts in epididymal and vas deferens, and total DNA levels in testes.
Maca Details
Species: Lepidium meyenii
Source of maca: Not stated
Location where maca was grown: Carhuamayo, Junín
Agricultural methods used: Autumn harvest, dried and stored for 2 years
Part of maca used: Hypocotyls
Form of maca: Aqueous extract
Dose: 1g/kg BW, oral administration
Outcomes
Results:
Daily sperm production was similar between all treatment groups.
Black and yellow maca improved epididymal sperm count (p<0.05).
Black, yellow, and red maca improved sperm count in vas deferens (P<0.05).
DNA concentration in the testis was similar to all treatment groups.
"Maca seems to act as a modulator of sperm count at the reproductive tract level."
Effect of butanolic fraction of yellow and black maca (Lepidium meyenii) on the sperm count of adult mice
About the Study
Type of study: Animal study
Population: Adult male mice, Swiss strain, average 90 days old
Aim of the study: To evaluate the effect of butanolic fraction of maca prepared in a similar way as described in a previous study and to determine the effect of alkaloid (butanol) fraction of maca on daily sperm production, epididymal sperm count and sperm count in vas deferens in adult male mice.
Maca Details
Species: Lepidium meyenii
Source of maca: Not stated
Location where maca was grown: Carhuamayo, Junín
Agricultural methods used: Not stated
Part of maca used: Not stated
Form of maca: Methanolic, butanolic and aqueous extract of black and yellow maca
Dose: 0.5 ml solution for 3 days, oral administration
Outcomes
Results:
Yellow maca had better antioxidant capacity compared to black maca (p<0.01).
Total phenolic content was better in the methanolic fraction than in the aqueous fraction of both yellow and black maca, though it was higher in black maca compared to yellow (p<0.01).
Methanolic extract of black maca resulted in higher concentration of sperm count in epididymis and vas deferens compared to yellow.
Methanolic extract of yellow maca increased daily sperm production more than methanolic extract black maca (p<0.05)
Both colors resulted in higher daily sperm production and epididymal sperm count compared to the control group (p<0.01)
Aqueous fractions of black maca showed higher daily sperm production compared to methanolic extracts of black maca, where are methanolic extracts of yellow maca has higher daily sperm production that butanolic and aqueous extracts.
Lepidium meyenii (Maca) increases litter size in normal adult female mice
PMID: 15869705
About the Study
Type of study: Animal study, 22-28 days
Population: 3-month-old, virgin female mice, Balb/C strain
Aim of the study: To investigate the effects of maca on several fertility parameters of female mice at reproductive age.
Maca Details
Species: Lepidium meyenii
Source of maca: Santa Natura Company
Location where maca was grown: Not stated
Agricultural methods used: Not stated
Part of maca used: Hypocotyl
Form of maca: Lyophilized aqueous extract
Dose: 1 g/kg BW, oral administration
Outcomes
Results:
Body weight, implantation sites, and gestational period were similar in the yellow maca and control groups.
Yellow maca group had significant increases litter size.
Other details:
Aqueous extract of lyophilized yellow maca was given to assess various fertility parameters of female mice 15 days prior to mating and during the first 7 days of gestation. Each female was mated with a single, untreated male of proven fertility.
The authors state that the effect of yellow maca on increased liter size was likely due to a reduction in embryo resorption.
The study confirms "...the traditional uses of Maca to enhance female fertility."
Hypocotyls of Lepidium meyenii (maca), a plant of the Peruvian highlands, prevent ultraviolet A-, B-, and C-induced skin damage in rats
About the Study
Type of study: Animal study
Population: 3-month-old, adult male rats, Holtzman strain
Aim of the study: To determine if two extracts of maca can provide dermal protection against UVR.
Maca Details
Species: Lepidium meyenii
Source of maca: Farmers in Pasco, Peru
Location where maca was grown: Ninacaca, in Pasco, Peru
Agricultural methods used: not stated
Part of maca used: Hypocotyls
Form of maca: Aqueous extract prepared with and without a heating process
Dose: 0.13, 0.65, or 1.3 mg/ml, topical application
Outcomes
Results:
Experiment #1: comparison of heated/boiling extract to non-heated/boiling extract:
The boiled extract had a better effect compared to the non-boiled extract on skin protection from UV rays, though both provided protection.
Experiment #2: Dose response of maca against UVA radiation.
Topical treatment of both yellow maca extracts reduced skin damage by UVB in a dose dependent manner.
Experiment #3: Dose response of maca against UVB radiation.
Topical treatment of both yellow maca extracts reduced skin damage by UVB in a dose dependent manner.
Experiment #4: Dose response of maca against UVC radiation.
Topical treatment of both yellow maca extracts can prevent the effect of UVC radiation in a dose dependent manner
Aqueous extract of yellow maca (Lepidium meyenii) improves sperm count in experimental animals but response depends on hypocotyl size, pH and routes of administration
About the Study
Type of study: Animal study, 3 days
Population:, male mice, N=105
Aim of the study: To evaluate the sperm count in male mice receiving boiled aqueous extract of yellow maca hypocotyls from different sizes, under different pH conditions and using two different routes of administration.
Maca Details
Species: Lepidium meyenii
Source of maca: Unknown, abstract only
Location where maca was grown: Unknown, abstract only
Agricultural methods used: Maca grown in different pH condition
Part of maca used: Hypocotyl
Form of maca: Boiled aqueous extract
Dose: 5 mg/0.5 ml/day, oral or intraperitoneal administration
Outcomes
Results:
Sperm count was higher in mice receiving yellow maca from the larger hypocotyl sizes.
The higher pH content of yellow maca reduced sperm count.
Oral administration of aqueous extract of yellow maca was the only effect route.
"In conclusion, the larger size of hypocotyls presented the best biological effect, and the low pH in the extract and the transformation after gastrointestinal passage are both important for its biological action."
Photoprotection against the UVB-induced oxidative stress and epidermal damage in mice using leaves of three different varieties of Lepidium meyenii (maca)
About the Study
Type of study: Animal study
Population: 3-month-old male mice, Swiss strain, N=36
Aim of the study: To evaluate the photoprotective effect of the leaves of the three different varieties of maca (yellow, black, and red) against the UVB-induced oxidative stress and epidermal damage in the skin of mice.
Maca Details
Species: Lepidium meyenii
Source of maca: Not stated
Location where maca was grown: Not stated
Agricultural methods used: Not stated
Part of maca used: Dried leaves
Form of maca: Not stated
Dose: 200 microliter per treatment, concentrated to 1 mg pyrogalol/ml
Outcomes
Results:
Red, yellow, and black maca demonstrated UVA/UVB absorptive properties and antioxidant activity.
Treatment of the three colors had a similar effect to the group treated with sunscreen, SPF 60.
Highest activity was from red maca, followed by black and then yellow.
Each of the three colors prevented the development of sunburns, epidermal hyperplasia, and leukocytic infiltration.
Black maca showed the highest superoxide dismutase levels and higher catalase levels in the skin.
Chemical Analysis of Lepidium meyenii (Maca) and Its Effects on Redox Status and on Reproductive Biology in Stallions
About the Study
Type of study: Animal study, 60 days
Population: Active breeding stallions, weighing 400-600kg, N=10
Aim of the study: To assess the chemical composition of Yellow Maca (Lepidium meyenii) and its biological activity on stallions following oral administration of hypocotyl powder.
Maca Details
Species: Lepidium meyenii
Source of maca: Not stated
Location where maca was grown: Junín, Peru
Agricultural methods used: hypocotyls exposed to the extreme temperatures, strong light conditions, and atmospheric pressure of a high altitude for two months, traditional drying methods were used.
Part of maca used: Hypocotyls
Form of maca: Powder
Dose: 20 grams daily, average dose of 4 gm/100 kg BW, added to the diet
Outcomes
Results:
88 compounds were identified in yellow maca including alkaloids, macamides, macaenes, and glucosinolates.
A progressive increase in antioxidant capacity was observed through day 60, positively impacting redox status.
Ejaculate volume increased gradually from day 0-60 (p<0.05) but decreased at day 90.
Sperm concentration and total sperm count steadily increased from day 0-90 (p<0.05).
Sperm motility reached maximum value after 60 days of maca administration.
Other details:
Study conducted during the breeding season (April to July).
Effect of Lepidium meyenii Walp. on Semen Parameters and Serum Hormone Levels in Healthy Adult Men: A Double-Blind, Randomized, Placebo-Controlled Pilot Study.
About the Study
Type of study: Human study, 16 week single-center, randomized, double-blind, placebo-controlled trial
Population: N=50, infertile men 28-52 yo, 11 dropped out of the study for various reasons including goal achieve (pregnancy of partner), new medical diagnosis, adverse event, and unknown reasons.
Aim of the study: Evaluate effects of maca on semen quality and serum hormone levels in infertile men.
Maca Details
Species: Lepidium meyenii
Source of maca: Provided by Andean Roots Ltd
Location where maca was grown: Peru
Agricultural methods used: Not stated
Part of maca used: Bulb
Form of maca: Gelatinized and powdered dried bulb, less than 7% humidity, preparation of the supplement and placebo followed the same methodology as reported in a previous study
Dose: 2.8 grams per day (7 capsules of 400 mg each); capsule form
Outcomes
Results:
Yellow maca group:
Sperm count rose by 15%
Sperm concentration increased by 40%
A significant decrease of free testosterone by 27%
Placebo group
Sperm count rose by 102%
Sperm concentration increased by 76%
Neither group showed a significant improvement in the sperm parameters measured.
Other details:
The authors state that the stimulation of sperm quality may happen by a non-steroidogenic mechanism since free testosterone decreased in the maca treated group, possibly due to secondary metabolites including macamides, macaenes, and other lipid fractions.
Authors include that this is inconclusive evidence, possibly due to preparation and variety of maca (based on the evidence, black maca seems more effects on semen parameters), dose, treatment duration and other lifestyle factors that can impact sperm health (i.e., diet, exposure to pollution).
Adverse event: Possible starch intolerance (N=1)
Evaluation of the effect of Lepidium meyenii Walpers in infertile patients: A randomized, double-blind, placebo-controlled trial.
About the Study
Type of study: Human study, 12 week, Double-Blind, Randomized, Placebo-Controlled Pilot Study
Population: N=20 healthy adult men, 20-40 years old (2 were excluded due to oligozoospermia)
Aim of the study:To evaluate the effects of maca on semen parameters and serum hormone levels in healthy adult men.
Maca Details
Species: Lepidium meyenii
Source of maca: Provided by Andean Roots SRL
Location where maca was grown: Cerro de Pasco region of Peru 4200-4500 meters above sea levels.
Agricultural methods used: Not stated
Part of maca used: Hypocotyl
Form of maca: Gelatinized and powdered
Dose: 1.75 g/day, 5 capsules containing 350 mg each
Outcomes
Results:
Increase in semen parameters after 12 weeks of maca use as defined by an increase in
Sperm count by 20%
Sperm concentration by 14%
Sperm motility by 14%
Semen volume by 9%
Morphology of sperm by 21%
No impact on hormone levels
Other details:
Authors report that the MOA remains unconfirmed, but may be due to lipid fraction (fatty acids and macamides)
The six most abundant macamides were reported
No adverse effects were reported