Is soy healthy or harmful?

Monsanto has announced a deal to sell a new genetically modified (GM) soybean that claims health benefits due to the addition of omega-3 fatty acids. However, the product has rekindled controversy about a food that some deem dangerous and others see as nature’s panacea.

The biotech company says that its new product could help fill a nutritional gap in the American diet, since most of us don’t get enough omega-3 fatty acids, which are essential for a wide range of normal body functions, including controlling blood clotting and building cell membranes in the brain. They also protect against cardiovascular disease, the leading killer of Americans.

“Consumers have been challenged to eat more fish and other foods with high levels of heart-healthy omega-3s. Now, soybeans may become a valuable source of omega-3,” Monsanto states on its website. 

Critics, however, contend that the new GM soybean, which is not yet on supermarket shelves, will encourage overconsumption of unhealthy foods, according to Center for Media and Democracy’s PR Watch. The Monsanto product is likely to be used in such processed foods as mayonnaise, soup, salad dressings, margarine, snack bars, baked goods, and other ready-to-eat foods, Food Product Design reports.

Is Monsanto’s newfangled variation healthy or harmful—and what do we know about the health effects of soy in general? Let’s take a closer look.

Soy is one of the most common foods in the American diet

Walk down just about any aisle at the supermarket and you’ll see soy products. This ubiquitous food is in everything from breads and crackers to baked goods, cereals, fortified pasta, beverages, imitation dairy products, sauces, and some baby formulas.

The average American consumes 38 pounds of soybean oil a year, according to the Environmental Working Group (EWG). It contains 120 calories per tablespoon.

A cup of soybeans contains about 298 calories, and a glass of soymilk has around 132. Other soy products include tofu, tempeh and miso, as well as soymilk, and soy-based foods such as soy burgers and soy ice cream.

More than 90 percent of soy is genetically modified

Ninety-three percent of soybeans grown in the United States are genetically modified, due primarily to Monsanto’s Roundup Ready soybeans, a variety genetically engineered to be resistant to glyphosate, an herbicide that kills weeds. The genetically modified variation allows farmers to kill weeds at will without harming their crops.

Now Monsanto has partnered up with DSM Nutritional Products with a new omega-3 soy product, SDA Omega-3 Soybeans, engineered to include stearidonic acid. For a healthy diet, it’s important to get a good ratio of omega-3 fatty acids (found primarily in fish and fish oil) to omega-6 fatty acids, found in many nuts and vegetable oils. Soybean oil is very high in omega-6 fatty acids.

The American Heart Association recommends regularly eating a variety of fish, as well as healthier oils like soy and safflower. In consultation with a physician, those with a history of cardiovascular disease or who need to lower their triglycerides may benefit from taking fish oil because it is rich in two types of omega-3 fatty acids called EPA and DHA.

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Are Monsanto’s new omega-3-enhanced GM soybeans a health food?

Monsanto’s new product—created by inserting genes from a primrose and a red bread mold into soybeans—can help balance the ratio of omega-3s and omega-6s in soy by enriching it with omega-3s. However, although stearidonic acid can convert to EPA, it does not convert to DHA. And high levels of DHA improve learning ability, along with helping lower the risk of diseases such as hypertension, arthritis and some cancers.

EPA has health benefits of its own as well, such as helping to prevent heart disease. But this new product will not replace the need for DHA, which is easiest for the body to digest from fish and fish oil. Plant oils such as soy do include the essential fatty acid ALA, which the body is capable of converting into EPA and DHA. However, this conversion process is inefficient, and may not be enough to maintain the ratio of omega-3s to omega-6s that is healthiest for the body. This means eating fish and fish oil is still the most optimal way to get both EPA and DHA fatty acids.

The Benefits of Soy

The Academy of Nutrition and Dietetics points out that soybeans are “a rich, unique source of high-quality, plant-based protein.” In addition to ALA, they are high in B vitamins and contain all nine essential amino acids, which aid in cell repair.

Soy critics have claimed that the plant can cause breast cancer, since it’s high in phytoestrogens that can stimulate the growth of breast cancer cells in the lab, but eating soy has not been shown to increase the risk of breast cancer.

In fact, research has shown that women who eat soy have a lower rate of breast cancer. In addition, an observational study tracking close to 75,000 Shanghai women showed that those who consumed more soy before being diagnosed with lung cancer lived longer when compared to those who consumed less soy.

However, the exact reasons for both studies aren’t entirely clear and there is no evidence that soy consumption directly prevents the disease.

Some additional research is promising, though more needs to be done. Researchers are investigating a soy-based treatment for colorectal cancer, which was presented at the American Association for Cancer Research’s annual meeting this year. And animal studies show that combining tomatoes with soy foods might be more effective in preventing prostate cancer, provided that they are eaten together.

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Is Soy Harmful?

Despite the benefits, soy is not without its critics. Since most soy has been modified genetically, opponents of GM food are especially worried. It’s difficult to either accept or dismiss their concerns about the safety of GM soy due to the lack of long-term research.

Another common criticism of soy is that it contains pesticide residues. The USDA GIPSA laboratory tested 300 soybean samples, and found 13 different pesticide residues (representing 12 pesticides) on the samples. Slightly over 90 percent of soybeans tested had the herbicide glyphosate (Roundup). While no samples exceeded the level that the USDA considers safe, some researchers have questioned if consuming glyphosate residue may be harmful to people.

Soy contains phytic acid and trypsin inhibitors, which research shows have the potential to inhibit the absorption of nutrients such as iron. Choosing fermented soy products (such as miso or tempeh) neutralizes this effect.

The phytoestrogens in soy may lower fertility in men; a small study shows that men who eat as little as a half serving of soy have an average of 34 million fewer sperm per milliliter than men who do not eat soy.

Finally, soy contains genistein, which appears in studies to alter reproduction and embryonic development in mice.

The bottom line? Soy seems to have some limited benefits, and potential downsides as well. Further studies may reveal more details about soy in time. Until then, eating a balanced diet with a wide variety of whole, unprocessed foods such as lean meat, fish, fruits and vegetables, whole grains, nuts and seeds is always a safe bet.

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