No myth is so absurd that one could not, even if only over rough edges, gain a little truth from it. With this one you not only grab your head in riddles, you may also get hungry: The consumption of yams should lead to the conception of twins. Can that really be? Or is it merely the result of a very imaginative rumour mill?
Twins are children of a mother and a father who were conceived on the same day or within the same cycle. A distinction is made between identical and fraternal twins. The former originate from one and the same fertilized egg cell, the latter are no more similar in their genetic material than other siblings, since they originate from two eggs which were fertilized by two sperm. In two egg twins, two eggs mature during the mother’s cycle. In monozygotic twins, one egg matures. But how does the yam root come into play?
What causes the fertilised egg cell (zygote) to split, as is the case with monozygotic twins, remains a mystery. When two or more oocytes mature in one cycle is somewhat clearer and statistics such as research have shown that not only genes contribute to a woman’s hyperovulation, i.e. two or more oocytes mature per cycle.
The issue of twins has long been fascinating, and in recent years researchers have become increasingly aware of African regions where twin births occur unusually often. A comparison of data collection in 75 developing countries shows that the highest rate of twins is found in Benin with 27 pairs per 1000 births and the second highest in Nigeria. In search of an explanation, the Yoruba people in south-western Nigeria and parts of Benin, as well as Ghana, who have a Yam root and a rich diet, were found.
Yams have been used for centuries to treat hormonal disorders and, since the possibilities of modern biotechnology, have also been used to isolate steroid hormones such as cortisone or progesterone. The yam root also contains phytoestrogens that can stimulate the secretion of the follicle stimulating hormone (FSH), which in turn can stimulate the ovaries to mature eggs. In women who hyperovulate, higher levels of FSH were found, which in turn led to the assumption of “more hormone, more oocytes”. But beware: this is still speculation and not proof that eating yams leads to twin pregnancies. If this were really the case, one would have to consume large amounts over a longer period of time anyway.
It is recommended to eat yams and sweet potatoes only in the first half of the menstrual cycle, i.e. until ovulation. If you tolerate the tuber, there is nothing against yam roots in your diet, but especially if you want to have children, you should definitely pay attention to a balanced and rich diet.
In this sense: Not everything that glitters is gold and not everything that tastes sweet are two children’s surprise eggs.