Soy milk: nutrition facts and health benefits

Jar of soy beans next to mason jar half filled with soy milk with blue and white straw
(Image credit: Getty Images)

One of the first plant-based milk alternatives on the market, soy milk helped millions of people to avoid dairy products back when veganism was in its infancy, and lactose intolerance was less understood. Now that there are so many more milk alternatives available, you may wonder how soy milk nutrition compares. 

Indeed, many concerns have been raised about the safety of soy milk consumption. Over the years, it has been accused of disrupting hormonal health, harming people with thyroid conditions, or even causing several types of cancer. It’s understandable then that you may think twice before putting a carton of soy milk into your shopping basket. 

But does soy milk deserve such a bad reputation? And can it be a good substitute for those with milk allergy? Here, we’ll have a closer look at its nutritional value and potential health benefits. And if you’re keen to learn more about a plant-based diet and how it can benefit your health, check out our plant-based diet for beginners for more tips.

Soy milk: nutritional information

How long does soy milk last?

Just like dairy milk, soy milk can be divided into two categories: UHT (ultra-high temperature)/shelf-stable and fresh/refrigerated. The UHT drinks undergo extensive heat processing to increase their shelf-life, whereas the refrigerated ones don’t. As a result, they come with different use-by dates and storage guidelines.  

Shelf-stable soy milk typically has a shelf life of six to 12 months. The refrigerated ones tend to have much shorter use-by dates – usually a couple of weeks from when they were produced – and stay fresh for about a week after being opened.

Soy milk in bottle and glass with soybeans in front

(Image credit: Getty Images)

What are the benefits of soy milk?

Soybeans are one of the best complete plant protein sources. One cup of cooked soybeans provides nearly 30g of this macronutrient, so if you’re not using the best vegan protein powder, soy milk can be a great way to meet some of your daily protein needs. 

According to a comprehensive review published in Nutrients, soybeans also contain a significant amount of calcium, manganese and selenium, as well as highly bioactive polyphenols called isoflavones. Multiple studies included in a review published in the Journal of the Academy of Nutrition and Dietetics have shown that high intake of soy products may lead to a reduced risk of dying from several different types of cancer, including breast, gastric, colorectal, prostate and lung, as well as cardiovascular disease and metabolic conditions. 

Many of these positive effects have been attributed to isoflavones. According to a review published in the Molecules journal, these polyphenols may play multiple important roles in the human body. It’s been suggested that they can protect against hypertension, regulate blood sugar levels, lower cholesterol levels, prevent atherosclerosis and decrease levels of inflammation. Soy isoflavones have also been shown to improve arterial flexibility, contribute to better gastrointestinal health and prevent osteoporosis-related bone loss. 

Woman pouring soy milk on cereal

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Far fewer studies have been conducted in relation to soy milk, but it’s possible to assume that this plant-based milk alternative will display similar benefits, albeit less pronounced due to a high water content. 

However, the results from available research are quite mixed. One review published in the Journal of Functional Foods found that regular soy milk consumption may significantly contribute to lower blood pressure, better blood lipid profile and an improved waist circumference. At the same time, there were no tangible differences detected in terms of body weight, ‘good’ HDL cholesterol, fasting blood glucose or markers of systemic inflammation. 

Another review published in the Complementary Therapies in Medicine journal assessed the impact of soy milk on blood serum lipids and found no significant associations between these two factors.

However, soy milk remains popular among vegans, vegetarians and health-conscious consumers due to its affordability and availability. You can easily find cheap cartons of soy milks in most grocery shops and supermarkets across the country, and there’s usually a range of different brands and flavors to choose from. What’s more, most manufacturers enrich their drinks with a host of vitamins and minerals that are likely to be in short supply in plant-based foods, making them a convenient dietary supplement for vegans and vegetarians.          

Is soy milk bad for you?

Soybeans and soy milk may have a number of health benefits, but there are some risks and considerations. 

If you compare soy milk to cow’s milk, the latter has a better absorption of protein in the gut. What’s more, soy milk contains several compounds often referred to as anti-nutrients. Anti-nutrients have the ability to interfere with natural digestion processes and reduce the absorption of certain nutrients in the gut. According to a review published in the Journal of Agricultural Science, there are several of these compounds present in soybeans. These components can lead to a lower intake of micronutrients, particularly vitamin A, vitamin B12 and vitamin D and even affect the formation of red blood cells. Thankfully, modern manufacturing processes are getting better at removing most of these anti-nutrients.

man drinking a soy milk cappuccino

(Image credit: Getty Images)

Another concern is related to the potential negative impact of soy isoflavones on thyroid function and iodine metabolism. It’s also been suggested that they may interfere with the absorption of synthetic thyroid hormones. However, researchers from the Thyroid journal pulled together results from 14 different trials and concluded that there is no evidence that soy consumption poses any risk to hypothyroid adults or iodine-deficient individuals. Still, to minimize any potential issues, soy food consumers are advised to ensure their iodine intake is adequate.      

Since isoflavones can mimic the effects of female reproductive hormones, many people have been worried about the potentially negative effect of soy on men’s health. But evidence suggests this isn’t the case. According to a meta-analysis published in Reproductive Toxicology, isoflavones do not impact the levels of testosterone, estradiol, estrones or sex hormone binding globulines in adult males. 

Certain soy milks can also come with high amounts of added sugars, particularly if they’re flavored. Since excess sugar consumption is bad for your health, always check whether the product is artificially sweetened.  

Anna Gora
Health Writer

Anna Gora is a health writer at Live Science, having previously worked across Coach, Fit&Well, T3, TechRadar and Tom's Guide. She is a certified personal trainer, nutritionist and health coach with nearly 10 years of professional experience. Anna holds a Bachelor's degree in Nutrition from the Warsaw University of Life Sciences, a Master’s degree in Nutrition, Physical Activity & Public Health from the University of Bristol, as well as various health coaching certificates. She is passionate about empowering people to live a healthy lifestyle and promoting the benefits of a plant-based diet.