Taking soy protein powder can be a great way to get the benefits of a high protein intake along with many ancillary health benefits that don’t come along with other protein supplements.
It might not be the best option for men, though.
In addition to the workout and health benefits that come alongside any protein supplement, soy protein can help lower your blood lipids, improve your cognitive function, and increase bone density in women.
For optimal benefits, you want a soy protein powder that’s going to deliver both the short-term fitness benefits and the long-term health benefits. Luckily, our research team has evaluated and ranked the best soy protein supplements on the market.
1. Jarrow Formulas Iso-Rich Soy
Jarrow Formulas makes a soy protein powder that is specifically formulated to be high in isoflavones, the compounds responsible for many of the health benefits of soy protein.
It includes isoflavone extracts from soy, soy protein isolate, and natural vanilla flavor. If you are specifically taking soy protein for its isoflavone content, this is the supplement for you.
2. BulkSupplements Soy Protein Isolate
BulkSupplements is what you want if you’re looking for soy protein that’s highly pure and has no other ingredients. This means it is high in soy isoflavones, the source of many of the positive health benefits of soy.
Though the packaging tends to be more difficult to re-seal compared to a standard tub of protein, it’s still a favorite among people looking for a pure and concentrated source of soy with zero additives.
3. Bob’s Red Mill Soy Protein Powder
Processed on dedicated equipment and certified gluten-free, Bob’s Red Mill is a good source of soy protein powder if having a supplement that is free of any potential allergens is important to you.
It’s also great for people who don’t like the taste of unflavored soy protein, but still want a supplement that is fairly clean and pure.
Bob’s Red Mill Soy Protein Powder is flavored with all-natural cocoa and almond butter, so you don’t have to worry about artificial flavorings or sweeteners.
4. Genisoy Soy Protein Shake
Genisoy provides soy protein isolate, but also takes the unique step of adding a blend of vitamins and minerals to its formulation.
This allows it to be a good source of everything from calcium to vitamin E to selenium, as well as several other vitamins and minerals. This makes it very well-suited for protein shakes being used as meal replacements.
5. Now Sports Soy Protein Isolate
Now Sports offers a soy protein powder that consists of 100% pure soy protein isolate. It’s got no additional additives, flavoring agents, or emulsifiers, making it a good option for those seeing a simple, minimalist soy protein supplement.
It also carries the “Trusted by Sport” certification, meaning that it’s been tested for the presence of compounds prohibited by anti-doping agencies.
6. Know-How Foods Soy Protein
Know-How Foods Soy Protein comes in a giant five-pound satchel, making it a good choice for people who go through a lot of soy protein powder in a short amount of time.
It’s only ingredient is soy protein isolate, so while it’s great for purists, it’s not the right call if you don’t like the slightly chalky texture and taste of soy protein powder.
7. Six Star Soy Protein
Six Star Soy Protein is a more comprehensive soy protein supplement that uses both soy protein isolate and soy protein concentrate to deliver its protein content.
This soy protein powder supplement flavored and sweetened with a combination of natural and artificial flavors, plus the artificial sweetener sucralose. It includes MCT powder, but its actual fat content is pretty low.
None of these individual factors are major problems, but they do add up to put Six Star Soy Protein at a disadvantage compared to what else is on the market.
8. Natural Nutraceuticals Organic Soy Protein Powder
Natural Nutraceuticals holds the distinction of being one of the few soy protein powders that is certified organic. It uses certified organic soy protein isolate and natural flavors, but a big downside is the use of cane sugar to sweeten the mix.
This drives up the sugar content to 8 grams of sugar per 17 grams of protein, so it’s definitely a no-go if your goal is a low carb or a low sugar diet. It would be better to see a similar supplement that doesn’t have as high of a sugar content.
9. EAS Soy Plant-based Protein Powder
EAS Soy is just a soy protein isolate protein powder that is flavored with fructose and natural flavorings. Low carb and low sugar enthusiasts won’t like the inclusion of fructose, which drives up the sugar content to be almost as high as the protein content.
Worse, the sugar content is all fructose, meaning it’s about twice as bad as if it were sucrose, which is a mixture of glucose and fructose. The high sugar content lands this soy protein supplement at the bottom of the rankings, despite being fairly popular.
10. Naturade Total Soy
Total Soy is designed as a meal replacement shake, so it uses soy protein isolate for its satiety-inducing properties as well as its health benefits.
It’s nice to see Total Soy include some extras like vitamins and minerals, but a big downside is the fact that this supplement is flavored by a large amount of fructose—there’s actually more sugar per serving than protein, making this a poor choice for anyone trying to lose weight or keep their sugar intake low.
Soy protein powder benefits and side effects
Taking soy protein powder gets you all the benefits of high protein intake with the added perks of several health benefits that you won’t’ get with other protein powder sources.
There are a lot of potential sources of protein to choose from for a protein powder supplement, but soy protein is a particularly good choice if you are looking to balance the fitness benefits of protein intake with the health benefits of soy isoflavones.
Soy protein intake, and particularly intake of soy isoflavones, have been deeply studied for their health benefits.
Soy isoflavones are compounds found naturally in soy products that researchers hypothesize are the causal link between soy food intake and lower risks for chronic disease.
Isoflavones modulate your body’s hormonal profile, as well as acting as strong antioxidants, which may explain their health benefits.
Soy protein may reduce your risk of cancer. This observation was initially found with regards to dietary soy intake and cancer risk.
A study published in 1994 in the journal Nutrition and Cancer examined the scientific literature on soy intake and cancer rates, both in humans and in animal models (1).
The study concluded that there was substantial evidence indicating that soy intake may reduce reduce the risk of a wide range of cancers, and further, that the most plausible explanation was the biological action of soy isoflavones.
Soy protein can lower your cholesterol and blood lipid levels.
A scientific review article published by James Anderson and other medical doctors in the New England Journal of Medicine surveyed a range of scientific studies on the relative effects of soy protein intake on levels of various markers of cardiovascular disease risk, including blood lipids (also known as triglycerides) and “good” and “bad” cholesterol levels (HDL and LDL, respectively) (2).
Anderson and colleagues found that high intake of soy protein was associated with a decrease in blood lipids and a decrease in LDL cholesterol, the “bad” subtype.
This suggests that soy protein powder may, in addition to improving your fitness gains in the short term, also improve your cardiovascular health in the long term.
Soy protein can improve your memory. One of the more surprising effects of soy isoflavone intake is that it seems to improve your short and long-term memory.
This was the conclusion of a study published in 2001 by researchers at King’s College in London (3). In their experiment, a group of students were randomly assigned to either a high-soy diet or a low-soy diet for a period of 10 weeks.
Short-term memory was assessed with a four-second pattern recognition test, and long-term memory was assessed with a picture recall test after a 20 minute break.
After the 10 week dietary intervention, the group that was on the high soy diet showed statistically significant improvements in both short term and long term memory.
The function of soy isoflavones is implicated here, too, because the low and high soy diets were intended to have vastly different isoflavone contents (0.5 mg per day versus 100 mg per day in the low and high soy diets).
While it would take a lot of soy protein powder to deliver 100 mg of isoflavones, a protein powder that’s fortified with extra soy isoflavones could easily deliver this level in a fairly moderate dosage.
Soy often gets a bad reputation for boosting levels of estrogen, which is counterproductive to the fitness goals of many men. Is there anything to these claims?
A review article by Kenneth Setchell at the Children’s Hospital Medical Center in Cincinnati, Ohio discusses the biochemical interactions of soy isoflavones inside the body and concludes that soy acts not as an estrogen hormone per se, but as a modulator of estrogen receptors (4).
The implications of this, according to Setchell, is that soy intake in normal dietary amounts is unlikely to cause the negative effects seen with frank estrogen supplementation.
However, some concerns persist thanks to population-scale studies such as one done on Japanese men and published in the journal Nutrition and Cancer in 2000.
This study looked at typical soy intake and blood levels of estrogen and testosterone among 69 Japanese men (5). This study found that higher soy intake was associated with lower levels of estrogen, but also lower levels of testosterone.
This finding is somewhat contradictory, and may simply be a result of the small sample size.
Still, athletes who are particularly concerned about keeping their testosterone levels (see: t boosters) as high as possible may want to opt for a different source of protein powder or opt for an estrogen blocker, too.
If you are taking soy protein powder for typical performance-enhancing purpose, the guidelines on the ideal dosage are pretty clear.
Endurance athletes should aim for 1.2 to 1.4 grams of protein per kilogram of body mass per day, while speed, strength, and power athletes should bump this up to 1.4 to 1.8 grams of protein per kilogram of body mass per day (6). Athletes who intend to rapidly gain muscle mass and strength may even want to push this up to the 2-3 gram per kg per day range.
However, for optimal health benefits, the necessary soy intake is somewhat lower. In a study on soy protein intake and cardiovascular health, the level of soy protein intake per day that was examined was about 50 grams of soy protein per day (7).
In terms of isoflavone content, to achieve high isoflavone levels, you may need to consume 50-75 grams of an isoflavone-fortified soy protein powder to achieve optimal levels for cognitive performance.
Soy protein powder is unique in its ability to deliver a highly concentrated amount of protein for athletic improvements alongside its ability to improve both physical and cognitive wellness in the long term.
These benefits are thanks to the content of soy isoflavones, natural compounds from the soy plant found in high concentrations in soy protein powder.
Soy protein intake is linked to a reduced risk of cancer, heart disease, and improved cognitive performance. The amount of soy protein you need to consume per day to get these benefits is fairly modest, and is easy to achieve with the right soy protein powder supplement.
Concerns about estrogen levels are perhaps overblown, but serious male athletes may want to seek out a different source of vegan protein powder if they want to maximize their testosterone levels and athletic performance.