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Yam is a starchy tuber consumed for centuries in Africa, the Caribbean, and Asia that now sparks scientific interest for containing diosgenin, a compound that in preliminary studies has shown potential to improve cognitive and memory functions in healthy adults and to help with blood sugar control, although the results are still preliminary
Yam is a tuber that appears in Caribbean stews, in fufu from West Africa, and increasingly on the shelves of Brazilian supermarkets and markets. Millions of people have consumed it for centuries as a staple food without knowing that it contains a compound called diosgenin. Researchers have discovered that this compound present in the tuber may influence the growth and communication of nerve cells, and a clinical trial has already tested its effects on the memory of healthy adults.
According to the Nutrients Journal, in addition to memory, the tuber is also being studied for its potential in controlling blood sugar levels. Yam is rich in fiber and resistant starch, components that slow digestion and may prevent the blood sugar spikes that cause that feeling of drowsiness after meals. Science does not classify yam as a superfood, but initial studies suggest that this tuber may offer measurable benefits that go beyond being just another carbohydrate on the plate.
What is yam and why does this tuber generate so much confusion
True yam belongs to the Dioscorea group and is a tuber with a rough skin and starchy flesh, different from the orange sweet potato that many confuse with it.
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This tuber is cultivated and consumed throughout Africa, the Caribbean, parts of South America, and the Pacific Islands.
In Brazil, yam is commonly found in markets and supermarkets, although many people do not know exactly what they are buying when they see names like cará and yam used interchangeably.
According to data from the U.S. Department of Agriculture, a 100-gram serving of raw yam has 118 calories, 28 grams of carbohydrates, 4.1 grams of fiber, and 1.5 grams of protein.
The tuber is especially rich in potassium (816 milligrams per 100 grams), vitamin C, and vitamin B6. This nutritional combination is what has led scientists to look at yam more closely: a staple food for millions of people that may also contain relevant bioactive compounds.
The compound in the tuber that may affect memory: what diosgenin does
Diosgenin is a plant chemical found in some types of yam. In simple terms, it is a compound that researchers suspect may influence the growth and communication of nerve cells in the brain.
In 2017, Chihiro Tohda from Toyama University in Japan led a placebo-controlled clinical trial that tested a diosgenin-rich yam extract in healthy adults.
The study analyzed 28 participants and reported that the tuber extract appeared to improve performance on standardized cognitive tests safely after weeks of use.
The result is interesting, but the researchers themselves point out that the study is small and that larger trials are needed to confirm whether regular consumption of this tuber protects the brain in the long term.
Diosgenin is promising, but we are still in the early stages of understanding what it actually does in the human body.
How the tuber may help control blood sugar
Yam is rich in complex carbohydrates, but two specific components of the tuber make a difference in blood sugar control: fiber and resistant starch. Fiber slows digestion and prolongs the feeling of fullness.
Resistant starch is a type of starch that resists digestion and behaves more like fiber, which helps prevent the blood sugar spikes that occur with simple carbohydrates.
A systematic review published in the British Journal of Nutrition analyzed whether yam or extracts of this tuber could help control blood sugar.
The conclusion was cautious: there is evidence of potential benefits, but the results varied according to the type of yam, preparation, and study design.
In practice, preparation makes all the difference: steamed or boiled yam retains its properties, while frying with sweet sauces loses the glycemic advantage that makes this tuber interesting for those monitoring sugar levels.
The antioxidants in the tuber and what science has yet to prove
Yam also contains antioxidants, compounds that help protect cells from damage related to inflammation. Researchers from the University of the West Indies published lab results suggesting that extracts of Jamaican purple yam affected the growth of cancer cells in a controlled environment.
But antioxidant activity in the lab does not automatically mean disease prevention in real life, and the researchers themselves classify these results as an early stage of investigation.
The same caution applies to claims about menopause. The tuber is sometimes marketed as a menopause product because diosgenin is mentioned alongside hormones. A clinical study in 2005 with postmenopausal women analyzed the effects of yam consumption on hormones such as estrone and estradiol.
The results suggest that there may be measurable effects related to hormones, but this does not mean that the tuber replaces conventional medical treatment. Wild yam supplements are also not the same as eating the food: concentrated extracts may have different effects on the body.
How to prepare the tuber to better enjoy its compounds
Yam can be boiled, baked, added to soups and stews, or made into flour and starch for use as a thickener in gluten-free recipes.
The most common varieties include the white and yellow yam from West Africa, the water yam (Dioscorea alata), which can be purple, and the Chinese yam used in Asian culinary and traditional medicine.
The best preparation to preserve the beneficial compounds of the tuber is cooking in water or steam, without frying or adding sugar.
Yam chips exist, but they are processed foods that quickly alter the nutritional profile of the tuber. The same goes for preparations with heavy sauces or sweet toppings.
Ultimately, yam is a starchy tuber that can be part of a balanced diet, especially when prepared simply and combined with proteins and vegetables. It is not a superfood, but it is a food with potential that science is just beginning to understand.
A food of centuries that science has only just begun to take seriously
Yam is a tuber that has fed millions of people for centuries and is now attracting scientific attention for containing diosgenin, a compound with potential effects on memory and blood sugar control.
The studies are still preliminary, the results are promising but not definitive, and no one is saying that this tuber cures diseases.
What researchers are saying is that it is worth studying further, and that a basic and accessible food may hold benefits that no one has measured so far.
Do you eat yam frequently? Did you know that this tuber contains compounds that are being studied for memory and sugar control? Or do you think it is an exaggeration to attribute special powers to such a common food? Leave a comment and share with those interested in food and health.
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