Let’s debunk the rumors about soy protein once and for all. It’s simply one of the best nutritional sources available.

When it comes to soy protein, there are a lot of long-held misconceptions, such as:
›› It’s for chicks only.
›› It will lower your testosterone levels.
›› It’s a lesser-quality protein powder than whey.
Whatever your preconceived notions are regarding soy protein, they are wrong, wrong, wrong (respectively). The truth is that if you’re avoiding soy protein, you’re missing out on a laundry list of benefits that are unheard of with any other protein powder.
According to new research, soy protein:
›› Enhances muscle recovery and growth.
›› Increases nitric oxide (NO) production.
›› Enhances fat loss.
›› Improves heart health and protects against certain cancers.
While studies have substantiated these attributes of soy, a lot of confusion still remains. The problem is that misinformed journalists and so-called nutrition experts perpetuate myths about soy that have been refuted with research. Here’s what scientists are now saying about the true properties of soy protein. Call it the new science, or “soyence,” if you will.

Soy: Myth Vs. Truth

Myth: Soy protein is a low-quality protein compared to dairy or egg protein.
Truth: Soy’s benefits as a protein source have long been misunderstood. Early research demonstrated that rats given soy protein as their only source of protein did not grow as well as rats given other protein sources, such as dairy. The reason for this is that soy is lower in the essential amino acid methionine. This caused many nutrition experts to make the claim that soy was not an effective protein for humans, particularly those looking to gain muscle mass. Yet today we know that rats have a much higher methionine requirement than humans, which is why rats don’t do as well with soy. We also know that soy is an effective supplement for athletes and those interested in putting on muscle mass. It’s just not good for rats that want to add muscle mass.
     When soy protein is compared to whey protein on what scientists call the protein digestibility corrected amino acid score (PDCAAS), which tests how much of a protein’s critical aminos get properly digested and delivered to the muscles to build muscle mass, it rates 100% — the highest score attainable, as does whey protein. In addition, soy’s amino-acid profile is very similar to that of whey. Soy actually has a higher concentration of the critical amino acids arginine and glutamine than whey has. Arginine is important for stimulating NO and growth hormone (GH) production. Glutamine has a laundry list of benefits that includes boosting muscle growth, decreasing muscle breakdown, enhancing immune function, decreasing fatigue during workouts, stimulating GH release and even aiding fat loss.
     Now we also know that soy is very effective for promoting muscle growth. One study presented at a 2006 Experimental Biology meeting reported that bodybuilders taking a soy protein shake twice a day for 12 weeks gained an equivalent amount of muscle mass as those taking a whey protein shake twice a day. A 2004 Ohio State University study found that trained men consuming 33 g of soy or whey protein from a protein bar for nine weeks significantly and similarly increased their muscle mass.
Scientific Fact: Soy protein boosts muscle growth as effectively as whey protein does.

Myth: Soy lowers testosterone levels.
Truth: Guys have long been afraid of soy protein because they were sold a lie that soy can lower testosterone and increase estrogen levels. The reason for this concern is that soy is rich in phytoestrogens. These powerful antioxidants provide soy its numerous health benefits, such as reduced risk of certain types of cancer (particularly prostate, colorectal and breast), lowered cholesterol levels and reduced the risk of cardiovascular disease.
     However, the chemical structure of these phytoestrogens closely resembles the structure of estrogen, hence the name. But despite these chemical similarities, research confirms that using soy protein does not reduce testosterone or increase estrogen levels. The 2006 study mentioned above that showed soy and whey led to similar gains in muscle mass also reported that soy did not alter the men’s testosterone or estrogen levels. These results were similar to numerous other studies showing that soy protein has no negative impact on males’ testosterone or estrogen levels.
     A recent study published in a 2007 issue of Cancer Epidemiology Biomarkers and Prevention, however, had male bodybuilders ditching their soy protein-powder jugs. The researchers from the University of Medicine and Dentistry of New Jersey stated in their abstract that males taking 56 g of soy protein powder for four weeks experienced a 19% decrease in testosterone levels. Journalists duly reported that soy decreased testosterone levels by 19%, which triggered widespread concern among males. Yet, upon further analysis of the data, it’s clear that this statement about a 19% decrease is false.
     The actual decrease was only 4%, and upon further analysis of the data, there are severe flaws in the study. For instance, one subject who was allowed to participate in the study had testosterone levels that were about 200% higher than the average testosterone levels of the other subjects. In fact, his testosterone levels were similar to those of someone using anabolic steroids, or just coming off of a cycle of steroids. The fact that his testosterone levels steadily dropped over the course of the study by 60% suggests that this subject had recently stopped taking anabolic steroids to participate in the study. If you remove his data from the study, it becomes obvious that there wasn’t even a 4% decrease in overall testosterone levels. In reality, the majority of the subjects experienced either a small increase in testosterone levels or no change in their testosterone levels at all during the four weeks of taking soy protein. Shocked at how sloppy these researchers were? Don’t be. What else would you expect from a group of researchers who misrepresented their data in the abstract?
Scientific Fact: Good research proves that soy protein will not affect your testosterone levels.

Myth: Soy protein doesn’t help with weight loss.
Truth: Research confirms that soy is very effective for weight loss, particularly around the waist and abs. In fact, a recent review article that was published in a 2008 issue of the journal Obesity Reviews concluded that soy does indeed have fat-loss potential. The researchers from the University of Alabama at Birmingham reviewed eight human studies, as well as several animal studies, to conclude that soy protein can aid fat loss, possibly by decreasing appetite and calorie intake.
     Supporting the theory of the Alabama researchers comes research from the University of Illinois showing that soy protein contains peptides (small proteins) that signal the brain that you are full and to decrease eating, as well as to rev up your metabolic rate so you burn more calories throughout the day. Another study from a different lab at the University of Alabama reported that subjects who drank a 20-g soy protein shake once a day for three months lost significantly more abdominal fat than those who drank a 20-g casein shake daily.
Scientific Fact: Soy protein enhances fat loss.

Myth: Soy can’t offer the muscle-building benefits that whey can.
Truth: Brand-new research finds that soy can boost nitric-oxide levels. Researchers from Virginia Polytechnic Institute and State University (Blacksburg) reported that the soy phytoestrogen, genistein, increased the amount of nitric oxide synthase (NOS) produced by the blood vessels. Since NOS is the enzyme that converts arginine to NO, this led to a significant increase in NO levels. Since soy also happens to be high in arginine, using soy protein is a smart way to boost NO levels and therefore blood flow to muscles, such as before workouts. An increase in blood flow during workouts delivers more nutrients, oxygen and hormones to the muscles.
     In addition, research finds that soy better protects your muscles from the oxidative damage that typically follows exercise and can lead to better muscle recovery after exercise as compared to whey. The 2004 Ohio State University (Columbus) study comparing soy and whey protein from protein bars showed that the guys eating the soy protein bars experienced better antioxidant protection following exercise. Another 2004 study also found that when trained men supplemented with 40 g of soy protein before working out for four weeks, they experienced better antioxidant protection following weight workouts as compared to whey protein.
     A 2005 study also found that subjects consuming soy protein for four weeks had less oxidative muscle damage following workouts as compared to those consuming whey protein. Because oxidative damage inhibits muscle recovery and growth, this means that soy can enhance recovery and muscle growth.
     The reduction in oxidative damage is likely due to soy protein’s high concentration of antioxidants, which neutralize free radicals to prevent the damage they do to muscle fibers. This allows your muscles to recover and grow following exercise, unencumbered by free radicals. The fact that soy also boosts NO levels could further enhance soy’s recovery abilities. NO enhances blood flow to muscles. This brings more nutrients, oxygen and anabolic hormones, which are all critical for recovery and growth.
Scientific Fact: Soy protein boosts NO levels and recovery, and thus muscle growth.


Isolate Your Soy
Soy protein comes from soybeans, which also contain fat and carbs. Because soybeans are a relatively poor raw source of protein, most manufacturers start with defatted soybean flour or flakes.
     The first step in creating soy protein is putting the soybean flour or flakes through a water- or alcohol-extraction process to remove some of the carbs. Next, the soy protein is dried and ground to produce soy-protein-concentrate powder. Soy concentrate is usually about 70% protein, with the rest being carbs and fat. Soy-protein concentrate can cause gas in some people due to the indigestible carbs it often contains.
     Soy concentrate can then be further processed to remove more of the fat and carbs, and gas-producing indigestible carbs, leaving an isolate form of protein that is higher than 90% protein. Not only is soy-protein isolate higher in soy protein, but it is also faster digesting — almost as fast as whey-protein isolate. The faster digesting time is critical when you want to get the aminos into your bloodstream and to your muscles ASAP, such as around workout time. So make sure to emphasize soy protein products that contain soy-protein isolate for better results.
 

Whey better:
Mix Soy Protein With Whey

Unless you have a milk-protein allergy or are vegan, we don’t recommend that you solely use soy protein. Your best option is to mix soy protein containing soy-protein isolate with whey protein powder at the following times of day:
›› Before workouts. Because soy boosts NO levels, taking it right before workouts gets more blood flow to the muscles to enhance energy during the workout and increase your muscle pump. Plus, getting in a fast-digesting soy-protein isolate before workouts helps to prevent muscle breakdown during the workout and boost protein synthesis immediately after the workout. Take about 10 g of soy-protein isolate mixed with 10 g of whey protein within 30 minutes before workouts.
›› After workouts. Research confirms that taking a fast-digesting protein such as soy-protein isolate immediately following workouts boosts muscle growth. Plus, the fact that soy provides antioxidant protection and enhanced blood flow to muscles means it helps with better recovery and growth. Go with about 20 g of soy-protein isolate mixed with 20 g of whey protein within 30 minutes after workouts.
›› Between meals. Getting in soy protein as a between-meal snack is not only a smart way to encourage muscle growth, but it can also help to encourage fat loss. The peptides in soy help to reduce hunger, so you eat less throughout the day and boost your metabolic rate so you burn more calories throughout the day. Less calories in and more calories burned equals a leaner you. Go with 10 g of soy-protein isolate mixed with 10 g of whey protein (which has also been shown to help reduce hunger) as a snack between meals.
›› As soon as you wake up. Another time of day you may want to consider using soy is right when you wake up in the morning. At this time your body is actually breaking down muscle for fuel due to the fast you undertook during the night. Because soy-protein isolate is a fast-digesting protein it will get into your bloodstream rapidly, supplying aminos that your body can use for fuel instead of aminos from your muscle protein. Because soy also boosts NO levels, it will deliver more of the aminos to the muscles to replace the protein that was broken down during the night. Take 10 g of soy-protein isolate mixed with 10 g of whey protein as soon as you roll out of bed in the morning.

Bottom line: Any time of day you drink a protein shake, adding soy to it will further the benefits you can expect.