Can Drinking Soy Milk Every Day Have Side Effects?

Soy milk was once thought to cause health concerns, but for most people, drinking soy milk every day is considered safe.
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Soy milk is a great way to get some protein into your diet, despite the fact that soy's reputation as a healthy food has seesawed in recent years.

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But experts are now confident that drinking soy milk every day is good for you, with few side effects that can cause concern or discomfort.

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Tip

Drinking soy milk every day is a good way to get protein. One to two 8-ounce servings of soy milk per day is considered safe and will give you many of the same nutrients as cow’s milk, according to the American Institute for Cancer Research (AICR).

That being said, watch out for soy milk varieties that contain added sugar, and limit these to one serving per day.

Soy Milk Nutrition Information

Per the USDA, a 16-ounce serving of soy milk contains:

  • Calories​​: 160
  • ​Total fat​​: 7.8 g
    • ​Saturated fat​​: 1 g
    • ​Trans fat​​: 0 g
  • ​​Cholesterol​​: 0 mg
  • ​Sodium​​: 179.8 mg
  • ​Total carbs​​: 8.5 g
    • ​Dietary fiber​​: 2.4 g
    • ​Sugar​​: 2 g
  • ​​Protein​​: 13.9 g

Tip

Some people don't like the taste of soy milk. To avoid what some call a chalky aftertaste, try shaking the container or testing different brands.

If you don't like the taste but still want the advantages of soy milk, you may prefer vanilla or other flavored soy milk. You'll get most of the same benefits as unsweetened, but if you drink soy milk on a regular basis, be aware that flavored options often come with added sugar.

Is Soy Milk Bad for You?

Soy milk and other foods made with soybeans were once hailed as superfoods with no downsides. Soy is a nutrient-dense form of protein, eaten in many parts of the world more regularly than in the United States.

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In vitro and animal studies have linked soy milk to cancer, so people started to question if drinking soy milk every day is bad for you. Interestingly enough, human studies have actually shown the opposite effect: that soy was linked to a reduced breast cancer risk, especially in premenopausal people, according to a March 2017 study in Cancer.

Soy protein doesn't seem to affect testosterone levels, according to August 2010 research in Fertility and Sterility.

Early research about soy milk may have been misleading, but new studies are shedding light on the many benefits of soy milk, according to experts at the Harvard T.H. Chan School of Public Health.

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Warning

If you are allergic to soy or soy milk, you shouldn't drink it, according to the Mayo Clinic.

Soy Milk Benefits

The primary ingredient in soy milk is soybeans. Drinking soy milk every day is not associated with any negative side effects, according to the Harvard T.H. Chan School of Public Health.

1. It's Lactose-Free

One advantage is that it does not have lactose, which makes it especially good for people with lactose intolerant. Soy milk is also a great option for vegans and vegetarians who avoid animal products.

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2. It's Low in Fat and Calories

Soy milk has less saturated fat than almond milk, and an 8-ounce cup of soy milk only has 80 calories, according to the USDA.

It also boasts high amounts of protein and similar nutrient content to cow's milk. Soy milk on it's own isn't high in calcium, but manufacturers often fortify it to have as much calcium as cow's milk.

3. It Contains Isoflavones and May Help Fight Inflammation

Isoflavones in soy have been linked to lower levels of inflammation, according to June 2016 research in ​Nutrients​.

Soy isoflavones and antioxidants may be beneficial for heart health, per a November 2017 review in ​Phytotherapy Research.

4. It May Help You Sleep

Soybeans are high in tryptophan — an amino acid the body uses to help make melatonin (also known as the "sleep hormone"), according to the USDA.

While the effects of drinking soy milk at night before sleep have not been studied, tryptophan is known to help regulate the sleep-wake cycle, per the U.S. National Library of Medicine (NLM).

5. It's High in Nutrients

Soy is also high in isoflavones, which have been linked to a lower risk of cancer, per the Harvard T.H. Chan School of Public Health.

Unsweetened soy milk may have the most balanced nutrient profile compared to other milk alternatives like rice milk, coconut milk and almond milk, according to McGill University. The only negatives may come from added sugar, flavoring or other additives, so check your labels carefully.

Soy Milk Side Effects

Soy products, including soy milk, are often thought to reduce hot flashes in menopausal people and keep osteoporosis at bay. But soy has different effects on different people, according to the Harvard T.H. Chan School of Public Health.

These researchers say that studies vary, in part, because some are conducted with animals, which may metabolize soy differently than humans. Also, people who have grown up eating soy products throughout their lives are thought to be better able to reap soy's benefits.

Soy Milk and GMOs

Some soy milk brands are made from genetically modified soybean crops. As of 2014, around 94 percent of all soybeans grown in the U.S. are genetically modified, per the USDA.

Genetically modified food crops are considered safe, according to the World Health Organization (WHO). But if you'd rather avoid GMOs, look for the Non-GMO Project label, which you'll find on several commercial soy milk products.

Phytoestrogen and Soy

Phytoestrogen is a chemical found in soybeans that can act like estrogen in the body, per December 2014 research in German Medical Science. This is why many people drink soy milk and eat soy products during menopause when the body has a natural drop in estrogen.

More research is needed to determine if soy or soy milk can benefit people going through menopause, per the Harvard T.H. Chan School of Public Health.

Phytoestrogen was once thought to contribute to decreased sperm production, but more studies are needed to determine if soy is bad for people assigned male at birth (AMAB).

Soy milk has not been shown to cause higher estrogen levels in people AMAB and children, per the study in ​German Medical Science​.

Anti-Nutrients and Soy

Soy milk contains some natural ingredients that can cut back on the body's ability to absorb some necessary nutrients and slow the digestion of protein and carbohydrates. These include trypsin inhibitors, lectins and phytic acids, along with indigestible oligosaccharides.

The benefits of eating nutrient-rich foods like soy outweigh the negative effects of anti-nutrients found in them, according to the Harvard T.H. Chan School of Public Health.

Soy Milk and Thyroid Problems

The thyroid gland regulates metabolism. People AFAB with thyroid problems are often cautioned to avoid foods with soy, but this is debatable.

People AFAB with normal thyroid function should not have any problems drinking soy milk or eating other foods with soy, per an October 2016 study in Public Health Nutrition. People AFAB with borderline abnormal levels of thyroid-stimulating hormone, or TSH, on the other hand, have a higher risk of developing thyroid problems from drinking soy milk every day.

If you take a thyroid replacement drug, you should wait 4 hours after you've taken your medication before drinking soy milk. If you take a thyroid supplement, you should also wait 4 hours after drinking soy milk before taking concentrated iron and calcium supplements, per the Mayo Clinic.

Tip

If you are at risk for thyroid problems, it's best to discuss drinking soy milk with your doctor.

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