What's in Soy Milk? A Closer Look at Ingredients and More - Healthline

Soy milk is a popular plant-based alternative to cow's milk.

It's commonly enjoyed by those who are intolerant to lactose — the type of sugar that's present in milk — or have a milk protein allergy. Other people drink it because they follow a plant-based diet or perceive it to be healthier than cow's milk.

In either case, you may wonder what's in soy milk and how its ingredients may impact your health.

This article takes a closer look at the ingredients, health benefits, and downsides of this popular plant-based dairy alternative.

Soy milk is made by blending soaked soybeans with water and straining the solids, leaving a smooth, milk-like liquid.

You can purchase both unsweetened and sweetened versions.

The unsweetened varieties generally contain only purified water and soybeans, though some brands also add salt, vitamins, and/or minerals.

The sweetened varieties contain a sweetener, usually cane sugar. They typically often include oil, salt, and vanilla to provide a flavor closer to that of cow's milk. Some versions also contain cocoa to create a chocolate flavor.

Sweetened and some unsweetened soy milk also contains a thickener or stabilizer. These additions help the ingredients in the milk remain in an emulsion, or uniform mixture, and retain characteristics like thicker texture and mouthfeel.

Here are a few commonly used thickeners and stabilizers in soy milk (1, 2, 3):

• Locust bean gum. This thickener is obtained from the seed of the carob tree, native to the Mediterranean region.
• Gellan gum. This type is produced by fermenting a carbohydrate source using a specific strain of bacteria.
• Carrageenan. This agent is extracted from red seaweed.

Of these, carrageenan has received the most push-back from consumers. That's because early research suggests a link between its consumption and inflammatory conditions like colitis, irritable bowel syndrome (IBS), rheumatoid arthritis, and colon cancer (4).

However, this link is not necessarily related to carrageenan, but possibly only with a form of degraded carrageenan called poligeenan. Unlike carrageenan, poligeenan is not approved for use as a food additive (4).

In fact, carrageenan is generally recognized as safe by the Food and Drug Administration (FDA). It's also deemed safe for the general population by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) (5).

Still, many brands have replaced carrageenan with locust bean or gellan gum due to the controversy surrounding its safety and poor acceptance by consumers.

Summary

Soy milk is produced from soybeans using a water extraction process. It may be sweetened or unsweetened and usually contains a thickener or stabilizer. You can purchase unsweetened, sweetened, and even chocolate-flavored versions.

Soybeans are rich in a variety of nutrients, making soy milk a nutritious beverage.

Here's a look at the nutrition provided by 1 cup (240 mL) of unsweetened soy milk (6):

• Calories: 80
• Fat: 4 grams
• Carbs: 4 grams
• Protein: 7 grams

Many popular brands of soy milk are fortified with vitamins and minerals like riboflavin, calcium, and vitamins A, B12, and D.

Unfortified, unsweetened soy milk tends to be a good source of vitamin B6, magnesium, folate, and zinc. Some brands also deliver vitamin K and iron.

Sweetened varieties typically contain cane sugar and provide around 5–15 grams of added sugar per serving (7).

Some people believe that plant-based products shouldn't be named using typical dairy-centered phrases like milk or yogurt, since this could convey that the products are nutritionally equal to cow's milk-based products (8).

Still, when it comes to fortified soy milk, it may not be so far-fetched, as it's similar to low fat cow's milk in terms of calories, fat, protein, vitamin D, calcium, and potassium (9).

Summary

Soy milk nutrition varies depending on whether it's sweetened or unsweetened and if it's fortified with vitamins and minerals.

Soy milk offers a variety of health benefits, supported by research.

May improve cholesterol

High cholesterol is a major risk factor for heart disease (10).

The foods you eat can significantly affect your cholesterol levels. Many foods, including soy milk, may have beneficial effects.

In a review, 5 out of 8 studies reported significant improvements in LDL (bad) and HDL (good) cholesterol as well as triglycerides in people who consumed between 1 cup (240 mL) to slightly more than 4 cups (1 L) of soy milk per day for 4–8 weeks (11).

Triglycerides are a type of blood lipid or fat that, when elevated, can increase your risk of stroke and heart disease (12).

The beneficial effects on cholesterol and triglyceride levels may be related to soy milk's content of certain proteins and isoflavones — a class of beneficial plant compounds found largely in soybeans (11, 12).

May reduce high blood pressure

Like high cholesterol, high blood pressure is a significant risk factor for heart disease. It also increases the risk of kidney disease.

Some research suggests that soy milk has blood-pressure-lowering effects.

In a small, older study from 2002, 40 participants with high blood pressure were randomized to consume about 16 ounces (1 L) of either soy or cow's milk every day for 3 months. At the end of the study, blood pressure levels had dropped in both groups (13).

Those who received soy milk had a 92% greater decrease in systolic (the top number) and 77% greater decrease in diastolic (the bottom number) blood pressure compared with those who received cow's milk (13).

Although it's been established that protein has beneficial effects on blood pressure, researchers in this study linked soy milk's blood-pressure-lowering effects with the drink's content of a specific isoflavone called genistein (13, 14).

Other studies have also confirmed the blood-pressure-lowering effects of soy, though not necessarily soy milk.

For instance, a review of 15 randomized controlled trials in healthy participants and participants with one or more heart disease risk factors like high blood sugar or cholesterol explored how various soy products may affect health (15).

The study demonstrated a significant reduction of 1.70 mmHg systolic and 1.27 mmHg diastolic blood pressure with soy products compared with placebo after 16 weeks (15).

Yet, because most of the studies in this review used soy protein or soy isoflavone supplements, it cannot be said for certain if the findings translate to soy milk.

The review also didn't address changes in body weight. If someone with overweight or obesity lost weight during the trials, their blood pressure could improve regardless of soy consumption (16).

In either case, the authors of the review suggest that the isoflavones found in soy are largely responsible for any blood-pressure-lowering effects. Ultimately, more research is needed to learn more on the topic.

May lower inflammation

Inflammation is your body's natural healing mechanism against injuries and infections.

However, when inflammation becomes chronic or long-term, it can be damaging and increase your risk of conditions like diabetes, heart disease, cancer, and rheumatoid arthritis (17).

Diet and chronic inflammation are closely tied. For instance, Western-style diets rich in saturated fats, refined sugars, and sodium are linked to inflammation and the development of chronic diseases (18).

On the other hand, diets rich in plant-based foods like soy have been shown to offer anti-inflammatory effects and decrease the risk of chronic disease (19).

One review of seven studies found that consuming soy milk significantly reduced two major inflammatory proteins known as c-reactive protein and tumor necrosis factor (TNF) (20).

It's thought that the isoflavones in soy milk inhibit the processes that generate these inflammatory proteins.

Still, whether these observed reductions in inflammatory markers have a meaningful impact on health requires further research.

May support weight loss and weight maintenance

Losing weight comes down to eating fewer calories than your body needs to support normal bodily functions and activity.

While studies haven't demonstrated consistent effects of soy milk on body weight, 1 cup (240 mL) of unsweetened soy milk contains just 80 calories, making it an excellent low-calorie choice (6, 21).

In addition to being low-calorie, it's also a great source of protein.

Protein offers three main benefits for weight loss — it promotes feelings of fullness, requires more calories than carbs or fats to digest and absorb, and helps you maintain muscle mass which means you may burn more calories at rest (22).

Another benefit is that the quality of soy milk protein is high.

Among all sources of plant-based protein, soy protein has the highest biological value. This means it contains the essential amino acids, also known as the building blocks of protein, in the right proportions required by humans (18).

In fact, the high biological value of soy protein is comparable to animal-based proteins like milk.

Summary

Soy milk may improve cholesterol levels, reduce blood pressure, lower inflammation, and promote weight loss.

There are only a few downsides to soy milk to consider. These include the cost and added sugar content.

Soy milk can cost in excess of $4 per half-gallon (2.3 L) while cow's milk generally costs less than $2 for the same amount.

If you have a food allergy or intolerance or avoid dairy products for other reasons, the cost may become less of a determining factor.

Meanwhile, if you tolerate cow's milk and don't mind drinking it, switching to soy may unnecessarily increase your grocery bill.

Another downside of soy milk to consider is the added sugar content of flavored varieties, which can range from 5–15 grams per serving.

The American Heart Association (AHA) recommends that women consume no more than 25 grams of added sugar per day and men no more than 36 grams (23).

Added sugars don't necessarily cause harm when consumed as part of an otherwise balanced, nutrient-dense diet. However, when consumed as excess calories, they can raise blood pressure, increase triglyceride levels, and contribute to unwanted weight gain (24).

As such, look for soy milk varieties with the lowest amount of added sugars. Or, simply opt for an unsweetened version.

Although soy is widely believed to lower testosterone and increase estrogen levels in men or increase breast cancer risk in women, there's no strong or consistent evidence to support these claims (25, 26).

Summary

The higher cost compared with cow's milk and the added sugar content of flavored varieties are potential downsides to consider with soy milk.

Soy milk is a nutritious beverage made from soybeans.

It's low in calories, high in protein, and rich in several vitamins and minerals — especially if fortified.

Regularly drinking soy milk may improve your cholesterol levels, reduce high blood pressure, fight inflammation, and support weight loss or weight maintenance.

A few downsides to consider are a higher cost compared with cow's milk and the added sugar content of flavored varieties.