Soy has become very popular lately as a meat substitute for vegans and vegetarians. The main reason for this is its high protein content, it contains all the amino acids a person need. In addition to this, it’s cheap to produce, as it produces a lot of protein per hectare. That’s why it’s fed to animals in factory farms as well.
So with so many apparent benefits, you might wonder what the disadvantages could be. Soy is notorious for its high phytoestrogen content. Phytoestrogens are substances found in certain plants, that have similar effects as estrogen, a female hormone, on the human body. Whether or not phytoestrogens are healthy for humans to ingest, is a subject on which opinions differ widely.
Part of the controversy relates to the fact that we don’t know with absolute certainty how the human body responds to this exposure to phytoestrogens. You might imagine that exposing your body to substances with an effect similar to hormones might have similar effects to those hormones. This is not entirely sure however.
There is reason to believe that phytoestrogens may take on a substitute role in our body, thereby prohibiting estrogen from doing its work. The phytoestrogen binds to the estrogen receptor which activates certain pathways in your cells, but the effect it has on this receptor is less strong than that of regular estrogen.
“Well then” You might say. “If phytoestrogens reduce the effect of estrogen, that shouldn’t be a concern to men then?” That’s not entirely true either. Although women normally have much higher estrogen levels in their body than men, the male body makes use of estrogen too, for its own purposes. Estrogen plays an important role in the developing male brain. Estrogen is known to protect neurons against damage.
Soy and Dementia
Three different studies, one in Hawaii, one in China and one in Indonesia, independently found that regularly eating soy products is associated with an increased risk of dementia in the elderly. When three different studies independently arrive at the same result, it’s necessary to be cautious. We don’t know exactly why this link is seen, some point their finger at the high aluminum content of soybeans, an element that has long been suspected to have a link to Alzheimer’s disease. An infant fed soy-formula would be exposed to an estimated 250 times as much Aluminum as an infant fed regular breast milk.
Soy and male fertility
As soy contains substances that have an estrogenic effect, there is reason to believe it may affect your fertility too. Soy fed to rats has been shown to reduce their testosterone levels and prostate weight. Men in sperm clinics who regularly eat soy are found to have lower sperm counts. In contrast to these results, some studies found that soy increased testosterone levels in rats. This is not per definition a good thing however, it can be indicative of hormonal problems.
The conclusion to draw from this
One important thing you need to understand is that soy is actually not as widely consumed in Japan and other Asian countries as most people seem to think. In addition, a large part of the soy consumed there is Tempeh, which is a fermented form of soy, which breaks down a lot of the phytoestrogens. Soy needs to be mixed with all sorts of spices by the food manufacturers, to hide its native unappealing taste.
When faced with evidence like this, my suggestion would be to be cautious and to avoid eating soy when you have a wide variety of healthy alternatives to choose from. If you eat a plant based diet, you’re not per definition in need of more protein overall, it’s just particular amino acids that are scarce. The limiting amino acid in your diet is lysine.
To ensure you receive enough lysine, you can consider eating sourdough bread, as the fermentation process increases the lysine content in the dough tremendously. Alternative, you can start eat more nuts and legumes. There are many different options and there’s no good reason to depend upon soy.