What is Mashua?

Mashua is a root crop from the high Andes. Its Latin name is Tropaeolum tuberosum. People eat the tuber (the fat, potato-like part that grows under the soil) boiled, baked or frozen.

It is also used as a folk remedy. The most common folk uses are for prostate trouble, for urine flow, and to cool down male sex drive. Andean stories say Inca rulers fed it to their soldiers for that last reason.

Here is the honest verdict. Mashua has deep roots as an Andean food and home remedy, but we found no human trials of it as a medicine. Long use on its own does not prove that a plant works, and that gap is not filled anywhere else on this page.

How does Mashua work?

No one has shown how mashua works in the human body. That is the plain answer.

Mashua belongs to the nasturtium family. It is rich in glucosinolates (natural mustard-oil compounds, the same family of chemicals that give watercress its bite). When you chop or chew the tuber, these break down into sharp-smelling compounds called isothiocyanates.

In lab dishes and in rats, these compounds can affect hormones and can kill bacteria. Rat studies are where the testosterone (the main male sex hormone) story comes from. Rats are not men, and a change in a rat does not tell you what happens in a person.

The same mustard-oil compounds can act as a goitrogen in large amounts. A goitrogen is something that can slow the thyroid gland, the gland in your neck that sets your body's speed. Cooking lowers this effect, but it does not remove it.

What forms does Mashua come in?

Fresh tubers, boiled or baked. This is the normal way people eat mashua.

Thayacha, a sweet Andean dish made from mashua that has been frozen outdoors and then thawed.

Dried tuber flour, stirred into soups or drinks.

A water brew (tea) of the tuber or leaves, used in home remedies.

Capsules and powders sold as supplements. The amount of active compound in these is rarely stated and is not checked by any standard.

Where it comes from:

Farmers in the Andes have grown mashua for well over a thousand years. It is a staple crop in Peru, Bolivia, Ecuador and southern Colombia, where it grows high up where few other crops survive.

It reached wider Latin American and Caribbean herb markets much later. Its folk name in some areas translates as "the man-tamer", which points to its old use for lowering male sex drive.

What does Mashua help with?

• Everyday nutrition and vitamin C intake: This is the use with the firmest ground under it. Mashua is a real food. It gives you starch for energy, some protein and a useful amount of vitamin C. As a vegetable it needs no proof beyond food science. Eating it as part of meals is the safest way to use it.
• Symptoms of an enlarged prostate: Andean healers use mashua for men who pass urine often or slowly as they get older. The reasoning is that mashua is said to lower testosterone (the main male sex hormone). No human trial has tested this. Do not swap a prescribed prostate medicine for mashua, and do not treat prostate symptoms at home without a check-up.
• Urinary complaints: Mashua tea is a common home remedy for burning or slow urine in parts of the Andes. It is used as a diuretic (water pill), meaning something that makes you pass more urine. There is no human trial behind this. Burning urine with fever or back pain needs a doctor, not a tea.
• Reducing male sex drive: This is mashua's best-known folk claim, and it is the reason some Andean men refuse to eat it. Rat studies do show lower testosterone after mashua feeding. Nothing equal has been done in men. Treat this as a story with a lab hint behind it, not a proven effect.
• Minor skin and wound care: Crushed mashua has been used on small cuts and skin sores in folk practice. Its mustard-oil compounds do kill some bacteria in a lab dish. No human study supports putting it on your skin. Raw plant juice can also sting or irritate.

Which foods are rich in Mashua?

1. Mashua tubers: the plant itself, eaten boiled, baked or frozen
2. Nasturtium leaves and flowers: the same plant family, with the same peppery mustard-oil compounds
3. Watercress, cabbage, kale and mustard greens: other foods rich in those same compounds

Practical Tips:

If you already eat a lot of cabbage-family greens, count mashua as part of that total.

What are the side effects of Mashua?

• Gas, bloating and stomach cramps
• Loose stools
• A strong peppery taste that some people dislike
• Mouth or throat stinging if eaten raw
• Passing more urine than usual after the tea
• A drop in sex drive, mostly reported by men
• Possible slowing of the thyroid gland (the gland in your neck that sets your body's speed) with very large amounts over a long time
• Rash or itching in people allergic to cabbage, mustard, watercress or nasturtium

Good to know:

Mashua is eaten as an ordinary vegetable by millions of people, so serious harm is rare. Most complaints are wind and stomach upset.

The two effects worth watching are the thyroid one and the sex-drive one. Both come from large or long use, not from a normal plate of food. Stop and speak to a doctor if you feel unusually tired, cold or slow, or if you notice swelling in your neck.

How much Mashua should you take?

• Recommended daily: There is no established medicinal dose for mashua. No trial has set one. As a food, a normal serving is about 100 to 200 g of cooked tuber, a few times a week. This is the amount we would stay near. For capsules or powders, follow the label on the pack and do not go above it. Makers rarely say how much active compound is inside, so one brand is not the same as another. Cook mashua before eating it. Cooking softens the sharp mustard-oil compounds and makes it easier on the stomach and the thyroid gland (the gland in your neck that sets your body's speed).
• Best time of day: Any time. It is a food, so most people eat it with lunch or dinner. There is no evidence that one time of day works better.
• With or without food: With food, or as food. Cooked mashua eaten with a meal is gentler on the stomach. Taking it on an empty stomach can cause gas and cramps.
• Time to effect: Nothing is known about how fast mashua works as a remedy, because no human trial has measured it. As a food it feeds you the same day. If you are using it for a health problem and see no change in four to six weeks, stop and see a doctor.
• How long to take it: As a vegetable in meals, mashua can be eaten as often as any other root crop. If you are taking it as a remedy, keep it short. Try four to six weeks, then stop and think about whether anything really changed. Do not take large daily amounts for months on end. That is where the risk of slowing the thyroid gland is highest, and no one has studied long use in people.