Yam nutrition, bioactive compounds and health effects reviewed
What it found
Yam tubers contain starch, fibre, minerals and bioactive compounds, and extracts have shown antimicrobial, antioxidant, anti-inflammatory and anticancer activity in lab and animal studies.
The review also notes antinutritional compounds in some species.
What they found
Animal and lab studies
Bioactive compounds
Yam contains steroidal saponins like diosgenin, the protein dioscorin, alkaloids, flavonoids and phenols. These compounds have shown antioxidant, anti-inflammatory, antimicrobial and anticancer activity in lab tests and animal studies.
Antinutritional compounds
Some yam species contain bitter or toxic compounds such as dioscorine and diosbulbin, which can cause paralysis of the nervous system. Other antinutrients like tannins, phytates and oxalates can reduce mineral absorption. Traditional processing like soaking, boiling and roasting reduces these compounds.
Anticancer activity
Compounds isolated from yam, including diosgenin and steroidal saponins, have shown cytotoxic effects against human cancer cell lines in lab tests. A polysaccharide from Chinese yam inhibited melanoma and lung cancer in mice.
Studies in people and animals
Therapeutic potential
Extracts from several yam species have shown antibacterial effects against human bacterial strains in lab tests. Animal studies have found anti-inflammatory effects, such as reduced paw swelling in mice and protection against duodenal ulcers in rats.
Other findings
Nutritional content
Yam tubers are mostly water, with starch making up as much as 80% of dry weight. They also provide protein, fibre, lipids, vitamins and minerals, though levels vary by species, variety and growing conditions.
Minerals in yam
Yam is a better source of potassium than cassava, potatoes, sweet potatoes and cereals like maize, rice and wheat. Some species also contain useful amounts of calcium, magnesium, iron, zinc and copper.
What the authors conclude
- They say that harmonizing indigenous and scientific knowledge of yam is needed to promote its use and contribute to UN sustainable development goals.
- They note that the general acceptability and long history of local consumption of yams may be attributed to its safety and portends high regulatory acceptability.
- They call for more research on yam production, utilization and the health benefits of its bioactive compounds.
How it was done
Yam is an underused crop that contributes to food security and income, especially in sub-Saharan Africa, but reports on its nutritional and therapeutic value are scattered and the diversity within the genus has caused confusion. The authors wanted to bring this information together to help yam meet its potential against hunger and poor health.
The authors reviewed published studies on the nutritional content, bioactive compounds and therapeutic effects of different Dioscorea species. They also looked at how yam is used traditionally and how its compounds might be applied.
What it can’t tell you
- Most of the therapeutic findings come from lab tests on cells or from animal studies. They cannot show what happens in people who eat yam.
- The review does not include clinical trials in people testing whether yam or its compounds prevent or treat disease.
- The amounts of bioactive compounds vary widely between yam species and varieties, so findings for one type may not apply to another.
Who paid
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- National Root Crops Research Institute, Nigeria; University of California, USA; Julius Maximilian University of Würzburg, Germany
The paper
- Title
- The Dioscorea Genus (Yam)-An Appraisal of Nutritional and Therapeutic Potentials
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Obidiegwu JE, Lyons JB, Chilaka CA (2020). The Dioscorea Genus (Yam)-An Appraisal of Nutritional and Therapeutic Potentials. Foods (Basel, Switzerland). doi:10.3390/foods9091304Free full textPubMed 32947880DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error