Why Women Should Not Consume Large Amounts of Soy During Preconception

Why Women Should Not Consume Large Amounts of Soy During Preconception

I would not recommend soy as a common food in woman’s diet, especially during preconception. Soy is an inflammatory food along with other foods such as gluten, dairy, sugar, and caffeine. Also, there are foods that are more nutrient rich to support fertility and the growth of a healthy baby. For an optimal pregnancy, one should eliminate this food as much as possible. Inorganic soy especially can raise estrogen, which would create an imbalance in fertility hormones. Excess estrogens, especially phytoestrogens, can cause issues in woman’s cycle such as the ability to ovulate and the luteal phase, where the uterus prepares to welcome a fetus from conception.

Occasional organic soy can be okay, especially if it is fermented natto. Natto is one of the best forms of vitamin K2, which is critical for building healthy bones and teeth for babies. Women should have ample amounts in their diet to ensure that a conceived baby does not deplete nutrients from the woman’s own stores in their bones. It can also be helpful to take or consume foods rich in calcium and magnesium to support bone health.

Personally, I feel that a diet that focuses on plants and has some animal proteins is the most nutrient rich diet, especially for woman who would like to become pregnant and have healthy babies. Cooked greens have ample amounts of folate, which research has shown prevents birth defects. Dr. Weston A. Price traveled the world studying healthy populations and showed how those who ate a whole foods diet with sources of vitamin K2, vitamin A, and vitamin D had longer life spans, stronger bones, and wider jaws. He even had child patients who struggled to grow, but they started thriving once they were given butter oil. I recommend a cod liver oil supplement because it has great amounts of vitamins A, D, and fish oil to support brain function and hormones. These critical vitamins are not found in soy, and so avoiding soy is also important because it creates a diet focusing on foods that are more nutrient rich.

Having a diet rich in plants, not only offers a diet rich in vitamins and minerals but also fiber. Having a high-fiber diet can help maintain satiety and blood sugar, which promotes a healthy weight and curbs women’s cravings for junk food. Those who eat fibrous foods that maintain their energy are more likely to have other healthy habits like drink more water and exercise, which also improve energy per the research. Fiber also supports digestion and prevents constipation. Those that are constipated tend to feel sick in their stomach, which is a common problem in pregnancy, and prevent women from getting adequate nutrients. It is also important to support eliminating toxins from the environment, which also artificially raise our estrogen. When eating fiber, it is important not to overconsume a fiber supplement because this could also create digestive issues and constipation, especially if not enough water is consumed.

On the other hand, I can understand that for various reasons, some women are vegans and vegetarians, and it is still important that they get adequate protein. Protein biological value measures the proportion of absorbed protein from a food that incorporate into the proteins of the organism that is consuming it. It is a measure of how much the digested protein can be used in protein synthesis. These provide the main source of nitrogen. Foods can either contain HBV or LBV protein. This means high biological protein or low biological protein. The foods that contain all of the essential amino acids have a high biological value. Foods that do not contain all of the essential amino acids have a low biological value. Animal proteins like meat, eggs, fish, and dairy have high biological values. Soy is the only plant that has a HBV. It is critical to eat the highest quality proteins possible for net protein utilization. It is not impossible for vegans and vegetarians to get enough quality protein, but it is more difficult. They also may have to supplement with nutrient and with vegan protein powders such as soy and pea protein.

In the long term though, those that rely on soy as a protein will still struggle to get adequate nutrition due to the trypsin inhibitors. Having trypsin inhibitors in a food would decrease its nutritional quality because proteins would not be broken down, digested, and absorbed into the body. Too much consumption of this can cause growth delays. It is present in some metabolic diseases. Therefore, it is important that when humans consume these foods, we specially cook and prepare them to inactivate these. It is important that these foods are heat treated and preferably soaked or sprouted.

In conclusion, I think there are many reasons to avoid soy during preconception, especially conventional soy. For women and their partners trying to conceive, they both should focus on having the most nutrient rich diet to support hormonal balance and provide the proper building blocks for their baby. There are many foods much more nutrient rich than soy. Therefore, having a diet with soy as a staple would automatically create a diet with less than ideal nutrition unless ample supplements were taken, which does not always offer the best absorption of nutrient forms. Also, soy has been shown to be an endocrine disruptor and inflammatory. Therefore, in preconception, soy should be avoided as much as possible.


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Stipanuk, M.; Caudill M. Biochemical, Physiological, and Molecular Aspects of Human Nutrition. Elsevier: St. Louis. 2013.

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