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Fertility Myth #2: Yams Can Increase Fertility
by Jennifer Redmond, Editor-in-Chief, April 27, 2010
Fertility Myth #2
- Recently many patients have said that they’ve heard that yams can increase fertility.
- Avocado, pineapple and yams are foods that are making news – or at the least getting people talking - about potential fertility benefits.
Dr. Pang has been getting a lot of questions lately about yams and fertility.
Here’s what we’ve uncovered.
The Yoruba people of Nigeria have the highest rate of fraternal twins in the world – approximately 45 for every 1,000 live births. They also happen to eat a diet rich in yams.
In 1996, a Yale medical student, Obinwanne Ugwonali, M.D., led some research after learning about the Yoruba’s high twin rate – eventually focusing on diet. The research hypothesized that the yams acted as anti-estrogens.
“Anti-estrogens fool the brain into thinking there is insufficient estrogen, causing it to release more of a hormone called gonadotropin and increase the ovulation rate,” he said. But a chemical link between yams and fertility has not isolated an anti-estrogen in yams.
According to Dr. Pang, “We don't know whether or not the diet is playing a role in the high rate of spontaneous twins in Nigeria. Other studies have demonstrated that the spontaneous twinning rate appears to vary among different races, highest in Africans and lowest in Chinese. The assumption has been that this is due to genetic predisposition. Further studies are needed to determine whether or not diet or genetics are the cause of these differences.”
And a final note about yams. The yams in Nigeria have a light yellow, almost white, flesh. The orange-fleshed variety that we see in the market labeled “Yams” are, in fact, sweet potatoes.