Good Soy Bad Soy

By Dr. Andra Campitelli, ND
with contributions by Lorette Steenman, RHN

The topic of soy consumption has been a controversial issue in the past few years.  In North America, soy became the “go-to” drink for those seeking a healthy dairy alternative. However, in recent years, soy has received a lot of negative press, with concerns over hormonal imbalances and effects on men and women who consume it due to the phytoestrogen content.  This has left many people confused as to whether or not they should avoid this popular drink.

The popularity of soy beverages in North America isn’t new anymore and the problem is that it has become ubiquitous in our foods and can now be found in almost every aisle of the supermarket. Soy beverages have been a staple in Asian diets for centuries. However, their average daily consumption varies, with studies showing anywhere from 10 to 50 mg of soy daily, whereas Americans are still only consuming 1 to 3 grams daily, a significantly lower amount than our Asian counterparts.  Yet, in terms of overall health, those individuals living in these countries who are consuming much higher amounts of soy seem to have more positive health outcomes.

The question then becomes, is soy harmful or helpful?

A consensus on this topic has been difficult to reach in previous years, given the large body of research being conducted on this topic and the variances from one study to the next.  ome studies use different types of soy, such as isolated soy fractions and proteins, versus other studies that are looking at soy consumption in food form and others not specifying which form of soy they are using at all. Differences were also also observed since soy components change based on the variety of the soybean, in addition to the multiple forms of soy being used.

So what is the general consensus amidst all this controversy?

Soy has a well-rounded amino acid profile for a plant protein and is a nutritionallycomplete protein, meaning that it contains adequate quantities of all essential amino acids necessary for the building and maintenance of human tissue. This makes it a common go-to choice for vegetarians and vegans.

Soy is more than just soy milk and tofu. Soybeans are processed to produce a variety of soy foods, such as soy oil, soy lecithin, soy meal, soy flour, soy protein concentrates and isolates. Then there are also the fermented soy products, such as tempeh, miso and natto, which are produced by inoculating the soybeans with various species of bacteria, fungi and molds.

Soy, The Positive and Negative

Research on the health benefits of soy generally revolves around the components of soy, namely a phytoestrogen content called isoflavones. Isoflavones are a plant-based substance that are structurally similar to the hormone estrogen. Due to their structural similarity, isoflavones have estrogen-like effects in various tissues in the body, such as reproductive, cardiovascular and skeletal tissues. The effect of this “excess estrogen” is where much of the concern arises, specifically in men and around estrogen-positive cancers.

It has been estimated that isoflavones are 1/400th to 1/1000th the potency of estradiol, a form of estrogen, meaning that although they can mimic the action of estrogen, it is to a much, much lesser degree. Many studies using 40 to 80 mg of isoflavones per day have shown benefit, specifically to women with menopausal symptoms, such as hot flashes and night sweats, in doses ranging from 50 to 100 mg daily. They have also been found to play a positive role in breast health, coronary artery disease and have a positive effect on our bones, which may prevent bone loss leading to a reduction in osteoporosis.

There has also been a link with soy and heart disease, with the FDA approving the health claim for soy protein and its effect on lowering cholesterol levels, encouraging 25 grams daily to potentially reduce the risk of heart disease.

On average, a typical serving of a soy food, such as tofu or soymilk, contains around 35 to 40 mg of isoflavones, with each gram of soy protein from traditional soy foods providing approximately 3.5 mg of isoflavones.

The Negative

Although there appear to be positive benefits from soy consumption, there does appear to be a downside as well. The primary problem lies in the form of soy being consumed, as often the commercially-consumed, non-organic soy products are genetically modified and processed, with over 90% of soybeans grown in the US being genetically modified. Soybeans are also heavily sprayed with herbicides, which are known carcinogens.  However, soybeans, even organically grown, still contain many harmful nutrients, which are destroyed during the process of fermentation.

Soy is found in an array of vegetarian products, but also in less obvious products such as breakfast cereals, baked goods, pastas, meat, poultry, fish products, and the list goes on.  This may be the reason that soy has become a frequent human food allergen and accounts for 90% of all food allergies, even for children.

Soy and Thyroid

Individuals who have been diagnosed with thyroid conditions should be cautious with soy consumption, as there is conflicting information as to the interaction of soy and thyroid hormones.  ome studies suggest that soy and soy isoflavones inhibit the production of thyroid hormones, while others have demonstrated that soy has a limited to no effect on overall thyroid function in healthy individuals. Many of the more recent studies support the latter conclusion; however some have observed that in euthyroid individuals, the amount of thyroid medication often needs to be increased. However, this appears not to be due to the interaction between soy and thyroid hormones, but because soy may inhibit the absorption of the medication. It is important to note that thyroid medication is generally taken on an empty stomach, so this should not be a large concern, but one should still execute caution.

Fermented vs. Unfermented Soy

As mentioned previously, many of the harmful nutrients found in soy are destroyed during the process of fermentation and consuming fermented versus unfermented soy will make a difference as to the health benefits or detriments. Even organically grown soybeans may still contain harmful ingredients, such as goitrogens and phytic acid, which may reduce the absorption of various nutrients. Unfermented soy can also interfere with protein absorption, increase the body’s need for vitamin D and impact vitamin B12 levels in the body. Unfermented soy may also contain MSG and may even contain heavy metals, such as aluminum.

However, the good news lies in fermented soy from organic soybeans, meaning miso, tempeh, natto, and fermented soy sauce, as these ingredients are actually beneficial to your health. Fermented soy foods are great sources of vitamin K2, a great source of vitamin B12 and contain many beneficial bacteria.

In summary, there are positive and negative benefits to soy consumption, and the positive benefits come from consuming organic, non-GMO, fermented soy products. Eating good quality soy products 2 to 3 times weekly is a healthy intake, allowing you to benefit from the positive health effects of this food.

This article was originally posted at the Truestar Health website.