What is Soy Protein Isolate? Is it bad for you? (2023)

FAQs

Is soy protein isolate really bad for you? ›

Soy is a good source of protein, fiber, and an array of important vitamins and minerals. It also contains health-promoting compounds like isoflavones. Though you may have heard concerns about soy's GMO status or phytoestrogen content, most scientific evidence suggests that there's no need to avoid soy products.

A dietary protein isolated from soybeans that contains isoflavone phytoestrogens. Soy protein isolate has been shown to reduce tumor incidence and growth in some animal studies, possibly by modulating estrogen metabolism, reducing tumor cell proliferation, and inducing tumor cell apoptosis.

It has been reported that soy protein intake can reduce serum cholesterol and triglycerides and also reduce accumulation of cholesterol and triglycerides in the liver which can lead to reduction of liver steatosis [8,9,10,11].

Soy protein is a word that could describe anything from soy milk to tofu to miso and beyond; it's used broadly to describe food made from soybeans. On the other hand, soy protein isolate is the isolated protein from the soybean that is engineered to create a higher quality of protein.

Soy is unique in that it contains a high concentration of isoflavones, a type of plant estrogen (phytoestrogen) that is similar in function to human estrogen but with much weaker effects. Soy isoflavones can bind to estrogen receptors in the body and cause either weak estrogenic or anti-estrogenic activity.

Soy protein isolate increases urinary estrogens and the ratio of 2:16alpha-hydroxyestrone in men at high risk of prostate cancer.

Whey isolate is by far one of the best forms of protein available on the market, and the reason behind it is that they generally lack the fats, carbs, lactose, and cholesterol that are found in many other forms of protein powder.

Whey isolate undergoes different processing than whey concentrate, which results in the isolate containing more protein with less carbs and fat per serving. However, these nutritional differences are small, and there is not strong support for different effects of these two types of whey protein.

Whey protein and whey isolate protein can be beneficial in many ways, including: Building muscles. Protein is essential for building strong muscles. Whey protein, in particular, contains types of amino acids that are great for muscles.

Using soy protein instead of animal protein reduces development of kidney disease in animals. Reducing protein intake preserves kidney function in persons with early diabetic kidney disease.

Is soy protein isolate bad for thyroid? ›

Hypothyroidism is generally treated with synthetic thyroid hormone — and soy has long been thought to interfere with the body's ability to absorb the medication. However, there's no evidence that people who have hypothyroidism should avoid soy completely.

Soy and its products have been shown to have anti-inflammatory properties, particularly in patients with diabetes mellitus and cardiovascular diseases [12,13,14,15]. Due to the inflammatory nature of UC, consumption of soy products may affect UC disease symptoms as well.

Soy protein isolate is a concentrated form of plant-based protein originating from soybeans. Like soy, it contains all nine essential amino acids, though its protein content is significantly higher at about 90 percent protein.

It may upset your stomach

Many people have allergies or intolerances that make it hard to digest soy. But even if you're not one of them, soy protein isolate may make your stomach rumble, says Slayton.

Numerous clinical studies have found that daily consumption of up to 50 grams of soy protein is not only safe, but may also be effective in improving risk factors for chronic disease such as some types of cancer, diabetes, and cardiovascular disease.

It contains unhealthy additives. Foodtrainers founder Lauren Slatyon, MS, RD, says that the chemical process used to isolate soy protein often leaves behind substances you don't necessarily want to be eating, like aluminum and hexane. “Think of bathing in toxic bath oil,” Slayton says.

This updated analysis, which included over 40 clinical studies, again found that neither soy nor isoflavones affect total or free testosterone levels.

According to a handful of studies, soy consumption may have a link to raising serum estrogen in humans (3), and potentially causing thyroid disorders (4). Animal studies have also suggested potential male infertility and breast cancer associated with soy consumption.

Soy comes from soybeans. It's made of isoflavones, which are a type of plant estrogen. It is structurally different from the estrogen in our bodies, and plant-based estrogen does not convert into the estrogen our bodies make when we eat it.

Is soy protein isolate good for menopause? ›

Soy isoflavones may help reduce hot flashes and night sweats that many women have during menopause. In clinical studies, postmenopausal women who eat high amounts of dietary soy protein (20 to 60 g per day) generally have fewer and less intense hot flashes and night sweats than those who eat less soy.

It is safe to drink protein shakes every day, but be sure to obtain the majority of your protein and other foods from whole food sources. Without whole food sources, you'll be missing out on other valuable nutrients that are vital for health and supporting your workout performance and recovery.

The main difference between the two is the amount of protein contained per scoop of protein powder. Isolate protein contains about 90 per cent of protein per scoop and a negligible amount of fat and lactose. On the other hand, protein concentrates contain 25 to 89 per cent protein (depending on the brand you buy).

A commonly recommended dosage is 1–2 scoops (around 25–50 grams) per day, usually after workouts. It's recommended that you follow the serving instructions on the packaging. Keep in mind that if your protein intake is already high, adding whey protein on top of your current intake may be completely unnecessary.

Although it's higher in fat than other types of protein, many studies show that whey protein lowers “bad” cholesterol and increases “good” cholesterol. Whey isolate is easier for some to digest than whey concentrate, but may lack some of the beneficial fat and nutrients of whey concentrate.

Soya protein consumption significantly reduced SBP and DBP in both hypertensive and normotensive subjects, and the reductions were markedly greater in hypertensive subjects. Significant and greater BP reductions were also observed in trials using carbohydrate, but not milk products, as the control diet.

Although eating soy-based foods can slightly reduce your low-density lipoprotein (LDL, or "bad") cholesterol level, the American Heart Association has concluded that soy doesn't significantly lower cholesterol.

Our results showed that soy consumption significantly improves SBP and DBP. Subgroup analyses identified a greater reduction in blood pressure among younger participants with lower baseline diastolic blood pressure, and in trials lasting for < 16 weeks duration.

1. Soy and soy-based products. Some research shows that regularly eating soy products like edamame, tofu, soy milk, and miso may cause a drop in testosterone levels. For example, one study in 35 men found that drinking soy protein isolate for 54 days resulted in decreased testosterone levels ( 3 ).

What foods should thyroid patients avoid? ›

So if you do, it's a good idea to limit your intake of Brussels sprouts, cabbage, cauliflower, kale, turnips, and bok choy, because research suggests digesting these vegetables may block the thyroid's ability to utilize iodine, which is essential for normal thyroid function.

May affect your thyroid

Soy foods don't affect thyroid function in people with healthy thyroids, found a Loma Linda University review of 14 studies. But, if you have an underactive thyroid you might want to watch how much soy you eat.

Red meat and processed meats, including bacon, hot dogs, lunch meats and cured meats. Refined grains, including white bread, white rice, pasta and breakfast cereals. Snack foods, including chips, cookies, crackers and pastries. Sodas and other sweetened drinks.

While people with inflammation should generally avoid dairy, soy protein products like tofu and tempeh have been found to reduce pain in joints according to a study from Oklahoma State University. An easy way to add soy to your diet is using soy protein powder.

However, MSG occurs naturally in ingredients such as hydrolyzed vegetable protein, autolyzed yeast, hydrolyzed yeast, yeast extract, soy extracts, and protein isolate, as well as in tomatoes and cheeses.

The latest research says whey protein is a better choice if you want to shed fat, pack on muscle, and boost testosterone. If you want a plant-based alternative, soy protein isn't necessarily a bad choice. In fact, the FDA states that it's better for your heart health than whey.

Chickpeas, lentils, lupine, sorghum, broad beans and many other legumes can replace soy in many formulations. Some of these are rich in high-quality protein and fiber and contain low levels of fat compared to soy.

A medium digesting protein is a protein that is typically digested within 3 to 3 ½ hours and includes a number of proteins such as whole egg protein, egg white protein, pea protein and rice/soy protein.

Soy is difficult to digest, which can cause gas, bloating and general discomfort.

Is soy protein good for gut health? ›

Recent studies have shown that soy-based foods have a significant positive effect on gut microbiota. One of the handfuls of plant foods to contain all nine essential amino acids, soy-based foods are today gaining popularity - not just for their many health benefits, but also because they positively affect gut health.

Drinking just two cups of soymilk or eating one cup of tofu produces blood levels of isoflavones that can be 500 to 1,000 times higher than typical estrogen levels in women.

Although diets rich in soy or soy-containing products appear safe and potentially beneficial, the long-term safety of very high supplemental doses of soy isoflavones is not yet known. One study in older men and women found that 100 mg/day of soy isoflavones for six months was well tolerated (154).

The Bottom Line:

Yes, you can go ahead and eat soy daily and feel good about it. Just be sure that you're consuming an appropriate amount—about three servings—of lesser processed soy foods. Some forms of soy like these below are more nutritious than others, so here's a quick rundown.

No. Soy intake does not raise or lower a man's testosterone levels. Derived from soybeans, soy is a high-protein substance found in many foods, such as edamame, tofu, tempeh, miso, soy flour, and soy milk. It can also be found in some supplements.

Soy Protein Does Not Lower Testosterone or Raise IGF-1 Levels in Men. Research from the University of Illinois by Bosland et al.

May affect your thyroid

Soy foods don't affect thyroid function in people with healthy thyroids, found a Loma Linda University review of 14 studies. But, if you have an underactive thyroid you might want to watch how much soy you eat.

Not enough evidence exists to suggest a link between soy consumption and hormone changes in the body such as increased serum estrogen, breast cancer risk, thyroid hormone imbalances, and infertility.

Abstract. Concerns that the phytoestrogens (isoflavones) in soy may feminize men continue to be raised. Several studies and case-reports describing feminizing effects including lowering testosterone levels and raising estrogen levels in men have been published.

What form of protein is best? ›

Whey protein is one of the most commonly used proteins and is best for day-to-day use. It contains all of the essential amino acids and is easily digested. It helps boost energy and can reduce stress levels. Whey isolates and concentrates are best to use after a workout.

The carbohydrate and fat content of whey protein isolate is very low, making isolate the better choice if you want to limit your intake of those nutrients. Both concentrate and isolate help you build muscle and get stronger as part of a protein-rich diet.

If you have lactose intolerance, whey isolate is a better choice than whey concentrate. Much of the lactose and sugars are removed from whey isolate during processing. But if you have a dairy allergy, both whey and whey isolate may upset your stomach. In that case, look for plant-based protein instead.

Unlike most other plant-based proteins, soy protein provides you with enough of all the essential amino acids to support muscle protein synthesis. That means that your body can use soy protein by itself to build muscle to the fullest extent.

Soy is completely safe to eat and is not going to have a significant impact on your testosterone levels. As long as you eat the recommended amount of 25 grams of soy a day, you likely won't experience any problems in your sexual health.

No. While there are worries that soy may affect testosterone, research has found that soy consumption did not decrease reproductive hormone levels (4).