Wondering what happens when you eat soy every day? Even if you aren’t regularly chowing down on tofu or edamame, you’re probably consuming more soy than you realize. That’s because, according to the Soy Nutrition Institute, processed forms of soy find their way into hundreds of common food products. In fact, the organization reports that a staggering seven percent of daily calories in the American diet come from soybean oil alone!
Soy comes in many forms, and some are more natural than others. Edamame (immature soy beans), soy milk, and tofu are all made from whole soybeans. Soy flour and soybean oil are found in many processed products, including meat substitutes, soy cheese, and energy bars, and soy sauce, tempeh, miso, and natto all contain fermented soy.
But when it comes to the possible health benefits, not all soy is created equal. Registered dietitian Jeanette Kimszal told The List, "When studied, the best benefits of soy came from whole food soy or fermented soy. Today a lot of products are putting soy into their ingredients, but we have no idea the quality or processing that goes behind these products." So, just what happens to your body when you eat soy every day?
It’s a bad idea to eat soy every day if you have a soy allergy
It should probably go without saying, but, if you’re allergic to soy, you should not eat soy every day.
According to Food Allergy Research & Education (FARE), a soy allergy is relatively common among children (affecting 0.4 percent of kids), but it rarely lasts into adulthood. In fact, the majority of individuals allergic to soy outgrow the allergy by age 10. According to Mayo Clinic, symptoms can include tingling in the mouth, hives, abdominal pain, and wheezing. While these symptoms are usually mild, life-threatening anaphylaxis can sometimes occur, especially in individuals with asthma and other food allergies.
But if you’re one of the unlucky few to still experience negative reactions to soy as an adult, it’s best to avoid soy completely. While some foods obviously contain soy (like tofu and soy sauce), processed forms of soy are used in many unlikely places, such as in certain canned soups and deli meats. Fortunately, soy is one of eight allergens that must be clearly listed on a product’s packaging under the 2004 Food Allergen Labeling and Consumer Protection Act. So read labels carefully if you’re allergic to soy.
You may receive health benefits from isoflavones if you eat soy every day
If you eat soy every day, you may wonder what exactly it is about soy, particularly in its whole or fermented forms, that makes it so healthy.
Soy contains isoflavones, a type of phytoestrogen, as noted by Oregon State University. Phytoestrogens are substances found in plants that can both mimic estrogen and block its effects in the body. Soy is the richest source of isoflavones. According to the Academy of Nutrition and Dietetics, one ounce of dry-roasted soybeans has 37 mg of isoflavones, while a cup of soy milk has 30 mg and three ounces of tofu has 20 mg. But more processed forms of soy usually have lower levels of isoflavones. The average soy-based meatless hot dog only has 11 mg and one ounce of soy-based mozzarella substitute has a measly 2 mg.
Many researchers believe isoflavones can improve health. A 2008 article published in Inflammopharmacology reported, "The potential health benefits of isoflavones may include protection against age-related diseases including cardiovascular disease, osteoporosis, hormone-dependent cancer and loss of cognitive function."
You could lower your cholesterol if you eat soy every day
Has your doctor told you that you need to lower your cholesterol? If so, you might help get your numbers under control if you eat soy every day.
In a meta-analysis led by Dr. Kyoko Taku and published in The American Journal of Clinical Nutrition in 2007, soy isoflavones were shown to reduce both total cholesterol and low-density lipoprotein (LDL, or "bad") cholesterol. The research team examined 11 large randomized and controlled studies conducted between 1990 and 2006, and concluded that soy isoflavones lowered total cholesterol by about 1.7 percent and LDL by about 3.58 percent. The isoflavones appeared to have no effect on triglycerides or high-density lipoprotein (HDL, or "good") cholesterol.
While those may sound like relatively modest decreases in risk, eating more soy would be a step in the right direction for the approximately 95 million Americans with a total cholesterol level greater than 200 mg/dL. According to the Centers for Disease Control and Prevention (CDC), having high cholesterol increases your risk for heart disease (America’s No. 1 killer) and stroke. If you’re looking to lower your numbers, you’ll want to avoid the worst foods for cholesterol.
If you eat soy every day, it may have an impact on your fertility
The isoflavones in soy could potentially have an impact on your ability to become pregnant, but the jury’s still out on how the two are connected.
In 2014, a team led by Dr. Bjarne K. Jacobsen published a study that examined how soy intake impacted the likelihood of becoming a mother. The study focused on more than 11,688 North American Adventist women. The researchers chose women from this particular religious denomination because, as a group, they had a generally healthy lifestyle and an average daily isoflavone intake much higher than the typical North American woman. The study concluded that the women who ate more than 40 mg of isoflavones a day had a three percent lower chance of ever giving birth.
But other evidence suggests that if you’re one of the more than 6 million women struggling with infertility, soy may be helpful. A 2015 study conducted by Dr. Jose C. Vanegas and colleagues that was published in Fertility & Sterility found "significant positive associations of soy intake with live births, clinical pregnancy and fertilization rates" among women using assisted reproductive technology (ART). So, what to do? If you’re concerned, speak with your doctor before you choose to eat soy every day.
If you’re worried about breast cancer, choosing to eat soy every day could help
The statistics on breast cancer in the United States are frightening: One in eight American women will get breast cancer in her life, and more than 40,000 women in the U.S. are expected to die of the disease in 2020 alone. The good news is that, if you eat soy every day, it doesn’t appear to increase your risk and may actually be beneficial.
Mark Windle, a registered dietitian and nutritionist for Savvy Fitness, told The List, "Soy intake may help to reduce the risk of breast cancer by up to 50 percent or so, especially in those who start eating soy-based products at a young age." He also notes that, until recently, researchers were concerned that isoflavones might actually increase a woman’s risk for certain types of breast cancer. But large studies have shown that higher intakes of soy and soy products don’t increase breast cancer risk and may actually protect against the disease.
And, if you do get breast cancer, eating soy may mean a smoother recovery. Windle noted that "soy intake also appears to lower the risk of cancer reoccurrence."
If you eat soy every day, is it bad for your thyroid?
Even though you probably don’t think about your thyroid much, this small gland in your neck has a big role to play. The hormones it produces control metabolism, growth, and development. According to the Kresser Institute, some foods, including soy, may negatively affect the thyroid. That’s because soy is a goitrogen, meaning it interferes with the thyroid’s ability to take up the iodine it needs to make hormones.
Soy’s effect on the thyroid may have other negative ripple effects in the body. As Dr. Carrie Lam, a doctor of functional medicine, told The List, "The thyroid and the adrenal glands are very interconnected; once the thyroid has been overworked, it can cause the adrenal glands to be overworked."
But not everyone agrees that soy is bad for the thyroid. One meta-analysis published in Scientific Reports in 2019 concluded that, while soy may raise the amount of thyroid stimulating hormone (TSH), it had no effect on two other thyroid hormones (free triiodothyronine and free thyroxine) and the change in TSH was not "relevant" for most healthy people, though it could "have a clinically significant effect" for "patients with compromised thyroid function."
You can get certain omega-3s when you eat soy every day, but there’s a catch
Omega-3 fatty acids get a lot of media attention, and there’s a good reason for that: This group of polyunsaturated fats have anti-inflammatory properties and have been credited with reducing risk of heart attack, obesity, and many chronic health conditions, as noted by Medical News Today. There are three types of omega-3s: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found mostly in plant oils, while EPA and DHA are found mostly in fatty fish. The National Institutes of Health (NIH) recommend that adult women get 1,100 mg of ALA a day for optimal health. Fortunately, half a cup of dry-roasted soybeans has a hefty 670 mg.
It’s important to note that although soy is high in ALA, it’s also high in omega-6 fatty acids. As Jeanette Kimszal, a registered dietitian with Thyroid Nutrition Educators, told The List, "Oils containing high levels of omega-6 fats can lead to inflammation. Soybean oil is one of these types of oils." So, if you eating soy every day, it will definitely boost your levels of ALA, but it won’t give you much of the other omega-3s, and your body may not appreciate the high omega-6 intake.
If you eat soy every day, you may better meet your protein needs if you follow a vegan or vegetarian diet
While many health professionals believe a vegetarian or vegan diet can provide important health benefits, there are concerns that people following a plant-based diet, including those who may eat soy every day, may not be getting enough of certain nutrients, including protein.
The recommended dietary allowance (RDA) for adult men and women is 0.8g/kg of body weight. That means a 130-pound woman would need approximately 47 grams of protein daily. Luckily, soy is packed with plant-based protein. One cup of cooked soybeans has 29 grams of protein, while one cup of plain soy milk has 7 grams, four ounces of tofu has 9 grams, and half a cup of tempeh has 16 grams.
And, when it comes to protein, quality matters just as much as quantity. Kathryn Schwab, a health and wellness researcher and coach at Tons of Goodness, told The List, "The soybean is notable not only for its total protein content but the quality of soy protein, which is higher than that of other plant proteins and similar to animal protein." In fact, unlike most forms of plant protein, soy is a complete protein, as noted by Healthline, meaning it contains all nine essential amino acids.
You could be more regular if you eat soy every day
If you eat soy every day, it could help prevent constipation because of their high fiber content. The consensus among health professionals is that getting enough fiber is one of the best ways to ensure regularity.
Women under 50 years old should aim to get 21 to 25 grams of fiber daily, as noted by Healthline. According to a report issued by the U.S. Soybean Export Council (USSEC), whole soybeans are an excellent source — a single serving has eight grams of fiber. Foods made from the whole bean, like tempeh and soy flour, are also good sources of fiber.
But the type of fiber also matters when it comes to easing constipation. As noted by WebMD, there are two types of dietary fiber, soluble and insoluble, and it’s the latter that matters most when it comes to going number two. Insoluble fiber can’t be digested by your body and so it "adds bulk to your stool," allowing it to travel faster and more easily through your colon. As the USSEC report points out, soybeans contain 70 percent insoluble fiber and 30 percent soluble fiber, making them a good choice for staying regular.
When you eat soy every day, it could make it harder for you to absorb certain minerals
No matter how nutritious the food you eat is, none of that matters if your body can’t actually absorb those nutrients. As noted by Healthline, phytic acid, also known as phytate, is found in all edible seeds, grains, nuts, and legumes, including soy. It allows these parts of the plant to store phosphorus, which they’ll need to grow into new plants. Soybeans are considered a high-phytate food, containing between 1 percent and 2.2 percent of phytic acid by dry weight.
Many studies, including a paper in the journal Molecular Nutrition & Food Research published in 2009, have found that the phytic acid in plants can impair the absorption of iron, zinc, and calcium in humans. According to Harvard Medical School, these minerals are among those essential for human health. Calcium is considered a major mineral because significant amounts are needed regularly (via Michigan Medicine). Iron and zinc are considered trace minerals because, although just as important, less is needed to maintain good health.
But the story of phytate is more complex than you might think. The Soy Nutrition Institute reports that phytate in soybeans doesn’t impair calcium as much as perhaps originally thought and may actually reduce your risk of developing colon cancer.
If you eat soy every day, you could lose weight
While there’s no magic bullet solution for weight loss, eating soy every day could help you reach your goals if you’re one of the 56.4 percent of American women trying to lose weight.
In a 2007 study published by Dr. Manuel T. Velasquez and Dr. Sam J. Bhathena in the International Journal of Medical Sciences, the authors concluded that "consumption of plant-based protein, particularly soy protein, may suppress food intake and increase satiety and/or energy expenditure that may reduce body fat gain and result in weight reduction, effects that may be useful for the prevention and treatment of obesity."
According to the National Institute of Diabetes and Digestive and Kidney Diseases, more than a third of Americans are overweight (a body mass index [BMI] of 25 to 29.9), a third are obese (a BMI of 30 or more), and about 7.6 percent have extreme obesity (a BMI of 40 or more). The organization notes that being overweight or obese puts individuals at higher risk for a number of chronic health conditions, including type 2 diabetes and high blood pressure.
Looking to shed some pounds? Then, you should learn all about the things everyone gets wrong about weight loss.
If you eat soy every day, will it give you an energy boost?
If you’re struggling through a mid-afternoon slump, could you put some pep in your step if you eat soy every day?
According to the UC Berkeley School of Public Health, B vitamins are often cited as natural energy boosters, but this claim can be misleading. The reality is that energy comes from the calories in the food we eat. B vitamins, however, help the body to convert those calories into adenosine triphosphate (ATP), which your cells use to function. So B vitamins may improve energy levels, but only in a roundabout way.
Soybeans contain a number of B vitamins, including niacin (B3), pyridoxine (B6), and folic acid (B9), but some forms of soy are better sources than others. For example, half a cup of tempeh contains about 25 percent of your daily B3 needs, 15 percent of your daily B6 needs, and 24 percent of your B9 needs. On the other hand, one cup of plain soymilk only contains approximately 9 percent, 6 percent, and 2 percent of those needs, respectively.
When you eat soy every day, you could be exposing yourself to too much of the metal cadmium
If you eat soy every day, you should know it could be contaminated with a metal you’ve probably never even heard of but one that could have a serious impact on your health.
According to the Environmental Protection Agency (EPA), cadmium is a metal found both naturally in the Earth’s crust and as part of many fertilizers. The EPA states that somewhere between one percent and ten percent of the cadmium in the food and water you consume will enter your body, and repeat exposure can cause kidney damage and brittle bones.
A 2006 study published in Science of the Total Environment by researchers Tracy Shute and Sheila M. Macfie found that soy plants uptake a significant amount of cadmium from the soil, and the beans can contain three to four times the maximum limit for cadmium set by the Codex Alimentarius Commission of 0.2 mg/kg. Another study, published in the same journal in 2012 by researcher Scott V. Adams and colleagues, observed that tofu, tempeh, and products such as tofu hot dogs, soy burgers, and tofu cheese had the highest concentrations of cadmium of all the foods they tested.
If you want to stay away from GMOs, you may not want to eat soy every day
Trying to cut GMOs out of your diet because you’re worried about how they may affect your health? You’re not alone. A 2018 survey by the International Food Information Council Foundation found that nearly half (47 percent) of Americans make at least some effort to avoid GMOs. Common reasons people give for steering clear of GMOs include fears about their "genetic instability"; their perceived potential to cause allergic reactions, cancer, and immune system disruptions; and concerns about lower nutritional value.
Another issue is the use of herbicides on herbicide-resistant GMO crops. According to nutritionist Mira Dessy, "One of the ingredients in [common herbicide] Roundup is glyphosate. This ingredient does not go away after the soybeans have been harvested, meaning if you are eating soy sprayed with glyphosate, you are consuming the glyphosate too." She pointed out that glyphosate has been linked to disruption of the endocrine system, which oversees hormone production within the body.
But if you’re looking for non-GMO soy, you’ll have to look pretty hard. According to the Non-GMO Project, soy is the No. 1 genetically modified crop in the world. A whopping 94 percent of soy grown in the United States is genetically modified. So, if you want to steer clear of GMOs, you won’t want to eat soy every day.