USANA uses soy as a major source of protein in its bars and drink mixes. A variety of factors have gone into this decision. The most important involve the fact that soy protein is nutritionally complete and high quality, and soy consumption has been linked with several long-term health benefits. In addition, soy protein is ecologically friendly. Its production has a much lotheyr environmental impact than does the production of most animal protein foods.
This does not mean they don’t appreciate the nutritional value of other proteins. Whey protein, for example, is also high quality from a nutritional perspective, and may have some advantages for those whose primary goal is to build muscle. It also has some advantages in taste and mouthfeel, although netheyr soy isolates are catching up in the sensory arena. They also recognize the value of rice, pea, and other protein concentrates, but note that few of these are as complete or balanced as soy and whey.
In general, though, our position is that a healthy diet includes protein from a wide variety of sources - including whole foods (legumes, whole grains, meat, dairy, and fish) as well as healthy processed foods. In this context, they believe that soy, whey, and other protein isolates and concentrates can play a role as components of healthy, well-balanced diets.
That said, they are also aware that the world of protein isolates and concentrates is filled with controversy. Much of what they see on the Internet and in certain popular magazines is strongly pro-whey and anti-soy, or strongly pro-soy or anti-whey, as if one or the other of these protein sources were “all good” or “all bad” for all people in all situations. In most instances, such stories are associated (either overtly or covertly) with food marketing campaigns. They are part of the “sticks and stones” that get thrown back and forth bettheyen the soy, whey, and meat factions who compete for your food dollars.
Is there any truth in what they are saying? Many times there is, but too often those truths are “half truths” or “facts spun out of context” with the intent of swaying purchasing behavior.
Is soy the preferred protein source for everyone? No. Clearly there are people who are sensitive or allergic to soy, and these individuals should avoid or limit their intakes of soy protein. Similarly, there are people who are allergic to dairy and who should avoid whey protein. People who are vegetarian or vegan may want to avoid whey protein because it is animal-based.
But to USANA scientists, these are not sufficient grounds for making the choice bettheyen whey and soy proteins an all-or-nothing, black-and-white proposition for the vast majority of people.
The industrial-grade bickering that has characterized much of the soy versus whey debate has left many consumers confused, concerned, and generally hungry for objective information on what they should eat. The purpose of this position paper is to summarize in an objective way our interpretation of what nutritional science has to say about several key issues that lie at the heart of arguments for and against soy protein.
In conclusion, USANA believes that soy is a healthy source of protein for the vast majority of people. Clearly there are people who are allergic and/or sensitive to soy, and those people need to limit their soy intakes or avoid soy all together. But the scientific research they have seen indicates that this group is relatively small.
That said, each of us is the best judge of what foods they should be eating. If you experience side effects from eating soy foods (even if you don’t have a diagnosed soy allergy), it makes full sense for you to minimize or eliminate sources of soy intake.
They encourage everyone to become an active “student” of nutrition - to seek out objective information from a variety of sources concerning the foods they eat. They encourage everyone to question information that doesn’t make common sense or that sounds too good or too scary to be true.
As always, the most solid, common sense advice they can provide concerning your protein sources is: a healthy diet is one that includes protein from a wide variety of sources, including whole foods (legumes, whole grains, meat, dairy, and fish) and healthy processed foods. In this context, they believe that soy, whey, and other protein isolates and concentrates can all play a role as components of healthy, balanced diets.
References:
The Nutritional Value of Soy Protein
Soy Allergies and Sensitivities
Soy and Weight Loss
Showing posts with label Soy Protein. Show all posts
Showing posts with label Soy Protein. Show all posts
Soy Phytates
Plants store phosphorus, an essential nutrient for plants and animals, in their seeds to support the growth of young seedlings. This phosphorus is stored in the form of phytate (inositol hexametaphosphate). Plant phytates are considered by some to be “anti-nutrients” because phytates consumed in the human diet can complex with essential minerals like iron and zinc and inhibit absorption in the gut. Others, however, consider phytates to be important food constituents that act not only as natural food-preserving antioxidants, but also help reduce risk of heart disease and cancer in those who consume whole grains, beans, seeds and nuts.
Soybeans contain significant amounts of phytate (1.3-1.4%), and some point to this as a reason to avoid soy foods. However, it is important to note that most whole grains, beans, seeds, and nuts are also rich in phytates (Table 1), and there is a wealth of science to support the fact that these foods are important constituents of a healthy, well-balanced diet that supports longevity and reduced disease risk. As such, it is difficult to argue that soy should be avoided based on its phytate content when so many healthy foods contain comparable levels of phytates.
It is also important to note that on a percent basis, isolated soy protein contains far less phytate than do whole soybeans.
Table 1. Phytate contents of some common grains, beans, and nuts. Values from NR Reddy and SK Sathe (eds). Food Phytates. CRC Press, 2001.
Soybeans contain significant amounts of phytate (1.3-1.4%), and some point to this as a reason to avoid soy foods. However, it is important to note that most whole grains, beans, seeds, and nuts are also rich in phytates (Table 1), and there is a wealth of science to support the fact that these foods are important constituents of a healthy, well-balanced diet that supports longevity and reduced disease risk. As such, it is difficult to argue that soy should be avoided based on its phytate content when so many healthy foods contain comparable levels of phytates.
It is also important to note that on a percent basis, isolated soy protein contains far less phytate than do whole soybeans.
| Food |
Phytate Content (%)
|
| Whole Wheat |
0.7-1.1
|
| Wheat Flour |
0.3-1.4
|
| Wheat Bran |
2.0-5.3
|
| Corn |
0.8-1.0
|
| Oats |
1.0
|
| Barley |
1.0
|
| Brown Rice |
0.9
|
| Soybeans |
1.3-1.4
|
| Soy Protein Isolates |
0.7-0.9
|
| Kidney Beans |
2.6-2.9
|
| Lentils |
0.4-0.5
|
| Chick Peas |
0.6
|
| Small White Beans |
1.2
|
| Great Northern Beans |
2.6-2.9
|
| Peas |
0.8-1.2
|
| Hazel Nuts |
1.9
|
| Walnuts |
0.6-2.4
|
| Almonds |
1.3-3.2
|
| Cashews |
0.6-2.0
|
Soy and Thyroid Function
Some claim that soy foods should be avoided because they contain compounds (isoflavones) that disrupt thyroid function. We view this as a “half truth” that has little relevance for healthy individuals who consume soy at moderate levels as part of a healthy, balanced diet.
The relationship between soy consumption and thyroid function has been studied for more than 70 years. Interest in the topic grew during the 1950’s and 1960’s when several cases of goiter were identified in infants who consumed soy formulas. Subsequently, using in vitro and animal research, scientists found that at high concentrations the soy isoflavones genistein and daidzein can inhibit the activity of thyroid peroxidase and 5'-deiodinase, key enzymes involved in thyroid hormone biosynthesis.
Since that time, 14 human clinical trials have evaluated the effects of soy foods and soy isoflavones on thyroid function. All involved presumably healthy subjects, and with few exceptions the soy product used was isolated soy protein.
With only one exception, all of the studies showed either no effects or minor and clinically irrelevant effects of soy on thyroid function. The one trial that noted marked anti-thyroid effects (and the one often cited in anti-soy literature) involved Japanese adults who were fed roasted soybeans that had been pickled and stored in rice vinegar. The soy protein and isoflavone content of this food was not characterized, and the study involved no control group. As such, its relevance must be questioned.
One large study evaluated the specific effects of soy isoflavone supplements on thyroid function. Postmenopausal women between the ages of 64 and 83 were given daily doses of 90 mg of soy isoflavones or a placebo. Thyroid hormone levels were tested at baseline and again at 90 and 180 days. After six months, any differences in thyroid hormones between the groups were statistically indistinguishable.
Today, most experts agree that soy foods and isolated soy protein have little if any effect on thyroid function in normal, healthy adults. That said, the potential for soy isoflavones to disrupt thyroid function should not be ignored by people who have compromised thyroid function and/or people with suboptimal iodine status. But these groups aside, we contend that soy is a good source of protein when consumed in moderate amounts as part of a healthy, balanced diet.
In support of this position, note that Asian populations have a long history of consuming soy products without significant occurrence of goiter. This also holds true for vegetarians who consume not only higher levels of soy, but high levels of fruits and vegetables that contain other flavonoids known to inhibit thyroid enzyme activity. These flavonoids include kaempferol (found in apples, onions, green tea), naringenin (found in citrus fruits), and quercetin (found in fruits and berries). Such compounds are widely distributed in plant-derived foods and are consumed at relatively high levels (up to 1 gram or more per day) by vegetarians and vegans. Despite this, vegetarian diets have not been linked with decreased thyroid function.
The relationship between soy consumption and thyroid function has been studied for more than 70 years. Interest in the topic grew during the 1950’s and 1960’s when several cases of goiter were identified in infants who consumed soy formulas. Subsequently, using in vitro and animal research, scientists found that at high concentrations the soy isoflavones genistein and daidzein can inhibit the activity of thyroid peroxidase and 5'-deiodinase, key enzymes involved in thyroid hormone biosynthesis.
Since that time, 14 human clinical trials have evaluated the effects of soy foods and soy isoflavones on thyroid function. All involved presumably healthy subjects, and with few exceptions the soy product used was isolated soy protein.
With only one exception, all of the studies showed either no effects or minor and clinically irrelevant effects of soy on thyroid function. The one trial that noted marked anti-thyroid effects (and the one often cited in anti-soy literature) involved Japanese adults who were fed roasted soybeans that had been pickled and stored in rice vinegar. The soy protein and isoflavone content of this food was not characterized, and the study involved no control group. As such, its relevance must be questioned.
One large study evaluated the specific effects of soy isoflavone supplements on thyroid function. Postmenopausal women between the ages of 64 and 83 were given daily doses of 90 mg of soy isoflavones or a placebo. Thyroid hormone levels were tested at baseline and again at 90 and 180 days. After six months, any differences in thyroid hormones between the groups were statistically indistinguishable.
Today, most experts agree that soy foods and isolated soy protein have little if any effect on thyroid function in normal, healthy adults. That said, the potential for soy isoflavones to disrupt thyroid function should not be ignored by people who have compromised thyroid function and/or people with suboptimal iodine status. But these groups aside, we contend that soy is a good source of protein when consumed in moderate amounts as part of a healthy, balanced diet.
In support of this position, note that Asian populations have a long history of consuming soy products without significant occurrence of goiter. This also holds true for vegetarians who consume not only higher levels of soy, but high levels of fruits and vegetables that contain other flavonoids known to inhibit thyroid enzyme activity. These flavonoids include kaempferol (found in apples, onions, green tea), naringenin (found in citrus fruits), and quercetin (found in fruits and berries). Such compounds are widely distributed in plant-derived foods and are consumed at relatively high levels (up to 1 gram or more per day) by vegetarians and vegans. Despite this, vegetarian diets have not been linked with decreased thyroid function.
Soy and Weight Loss
Some claim that soy-based meal-replacement formulas are ineffective for weight loss. However, the fact is that soy protein has been used effectively as a component of weight loss diets for more than 20 years. Animal studies have shown that soy protein and its associated bioactive isoflavones and peptides can have beneficial effects on glucose metabolism, fat metabolism, insulin sensitivity, metabolic rate, food intake and weight loss. Studies in humans have further shown that increased intakes of soy or animal protein can increase metabolic rate, decrease appetite, and increase satiety. Furthermore, randomized clinical trials and clinical weight loss studies have shown that diets based on soy protein are every bit as effective - if not more effective - than diets based on dairy protein when it comes to helping people lose weight and abdominal fat.
The truth is that weight loss is much more a function of reducing caloric intake and increasing calories burned through exercise, as opposed to simply using soy or whey protein in the diet.
The truth is that weight loss is much more a function of reducing caloric intake and increasing calories burned through exercise, as opposed to simply using soy or whey protein in the diet.
The Nutritional Value of Soy Protein
Several scales for assessing the nutritional value of protein have been developed over the years. These have been used to rate various proteins for their ability to support growth, supply important amino acids, and generally satisfy the human protein requirement. The first broadly accepted standard was the Protein Effectiveness Ratio (PER). Developed in 1919, this method focused on the growth-supporting characteristics of a given protein, and it used rats (rather than humans) as the test animal. Because of the metabolic differences between rodents and humans, this method has been largely discredited and is rarely used today.
A second method, the Biological Value (BV) scale, is based on the retention of protein nitrogen by the body. It is thought to be a good measure of protein utilization. The BV scale stretches from 0 to 100, with a score of 100 indicating that virtually 100% of a given protein's nitrogen is retained by the body. Some people - particularly in the sports world - use this method, but it is not widely accepted within the community of nutritional scientists.
Most nutritionists (and many in the sports sector) now consider the Protein Digestibility Corrected Amino Acid Score (PDCAAS) to be the international standard for assessing protein quality. This approach, developed by the Food and Agriculture Organization and endorsed by the U.S. Food and Drug Administration, considers the amino acid balance of a given protein as it compares with the amino acid needs of humans, with specific reference to 2-5 year old children. It also takes into account the digestibility of the protein, or how fully the protein is broken down and absorbed by the body. The PDCAAS scale stretches from 0.0 to 1.0, with a score of 1.0 indicating that the protein completely satisfies human needs from a quality perspective.
During the 1990’s, whey protein became the protein of choice among bodybuilders, due in large part to an intense and successful marketing campaign sponsored by the dairy industry. That marketing promotion was based on the fact that some whey protein isolates have a rating of 100 on the BV scale. In comparison, egg-white protein (the traditional standard for bodybuilders) typically ranks in the 90’s, while most fish, beef, and soy proteins rank in the 70’s on the BV scale. (You will see a wide variety of BV scores for these foods because different people express the ratios in different ways, and the techniques for measuring BV are imprecise and not easily replicated from one experiment to another.)
However, when the PDCAAS approach is employed, soy protein isolates, whey protein isolates, and egg white protein all score a complete 1.00, meaning they all exhibit very high - and essentially equivalent - nutritional value in supporting human health.
The high PDCAAS score for soy protein isolates speaks to two important points. First, soy protein is well-digested and absorbed by humans. (This is the “D” of PDCAAS). Second, soy protein is complete. It contains all the essential amino acids in a proper balance for human growth, development, and health. (This is the “AA” of PDCAAS.)
Some authors have claimed that soy is lacking in the essential amino acid methionine, as if to imply that soy contains no methionine. This is incorrect. Soy may not be rich in methionine, but it contains enough to supply human needs under most circumstances. Furthermore, it is important to point out that human methionine requirements can be partially met by another sulfur-containing amino acid (cysteine). When cysteine + methionine content is considered, soy protein is nutritionally excellent.
A second method, the Biological Value (BV) scale, is based on the retention of protein nitrogen by the body. It is thought to be a good measure of protein utilization. The BV scale stretches from 0 to 100, with a score of 100 indicating that virtually 100% of a given protein's nitrogen is retained by the body. Some people - particularly in the sports world - use this method, but it is not widely accepted within the community of nutritional scientists.
Most nutritionists (and many in the sports sector) now consider the Protein Digestibility Corrected Amino Acid Score (PDCAAS) to be the international standard for assessing protein quality. This approach, developed by the Food and Agriculture Organization and endorsed by the U.S. Food and Drug Administration, considers the amino acid balance of a given protein as it compares with the amino acid needs of humans, with specific reference to 2-5 year old children. It also takes into account the digestibility of the protein, or how fully the protein is broken down and absorbed by the body. The PDCAAS scale stretches from 0.0 to 1.0, with a score of 1.0 indicating that the protein completely satisfies human needs from a quality perspective.
During the 1990’s, whey protein became the protein of choice among bodybuilders, due in large part to an intense and successful marketing campaign sponsored by the dairy industry. That marketing promotion was based on the fact that some whey protein isolates have a rating of 100 on the BV scale. In comparison, egg-white protein (the traditional standard for bodybuilders) typically ranks in the 90’s, while most fish, beef, and soy proteins rank in the 70’s on the BV scale. (You will see a wide variety of BV scores for these foods because different people express the ratios in different ways, and the techniques for measuring BV are imprecise and not easily replicated from one experiment to another.)
However, when the PDCAAS approach is employed, soy protein isolates, whey protein isolates, and egg white protein all score a complete 1.00, meaning they all exhibit very high - and essentially equivalent - nutritional value in supporting human health.
The high PDCAAS score for soy protein isolates speaks to two important points. First, soy protein is well-digested and absorbed by humans. (This is the “D” of PDCAAS). Second, soy protein is complete. It contains all the essential amino acids in a proper balance for human growth, development, and health. (This is the “AA” of PDCAAS.)
Some authors have claimed that soy is lacking in the essential amino acid methionine, as if to imply that soy contains no methionine. This is incorrect. Soy may not be rich in methionine, but it contains enough to supply human needs under most circumstances. Furthermore, it is important to point out that human methionine requirements can be partially met by another sulfur-containing amino acid (cysteine). When cysteine + methionine content is considered, soy protein is nutritionally excellent.
Soy Allergies and Sensitivities
Soy is on the Food and Agriculture Organization’s list of the eight most prevalent food allergens. This list includes milk, eggs, fish, crustacea, wheat, peanuts, tree nuts, and soy. Together, these foods account for about 90% of food allergies.
That said, it is important to understand that these high-profile food allergies differ widely in their incidence, severity, and symptoms, and that soy protein - relative to milk and nut proteins, for example - is a relatively mild allergen. Consider the following:
Beyond true allergic reactions, some people may be sensitive to the “non-digestible” sugars and fiber in soy. These components can cause abdominal bloating and gas, just like the sugars and fibers in most beans and just like the lactose in milk. Such symptoms are generally reduced, if not eliminated, when people use highly refined soy protein isolates which are 90-92% soy protein and only 3-4% carbohydrate (fiber plus simple and complex sugars and starches).
That said, it is important to understand that these high-profile food allergies differ widely in their incidence, severity, and symptoms, and that soy protein - relative to milk and nut proteins, for example - is a relatively mild allergen. Consider the following:
- Milk and peanut allergies are each 5-6 times more prevalent than soy allergies. In fact, the true incidence of soy allergy - as confirmed by double blind, placebo-controlled food challenges - is quite low. Research indicates that allergic reactions to soy occur predominately in children less than four years of age, and most estimates agree that <1.0% of children (probably 0.2-0.4% of children) have true soy allergies. Moreover, 90% of children who have reactions to soy outgrow the allergy by age four. Given these statistics, it is safe to assume that <0.1% of adults (fewer than 1 in 1,000) are allergic to soy.
- Food allergen reaction thresholds, or the minimum oral dose of protein that elicits an allergic response, tend to be several orders of magnitude (more than 100-1000 times) higher for soy than for milk and peanut proteins. In other words, it takes 100-1000 times more soy protein than milk or peanut protein to initiate an allergic response in sensitive people.
- Soy allergies tend to produce mild symptoms relative to other food allergies. In a summary report of clinical food challenge studies, it was noted that in 80% of reported cases, symptoms of soy allergies were minimal to mild, with the remaining 20% being moderate. No severe allergic reactions to soy were reported. In comparison, milk and peanut allergies produced minimal-to-mild symptoms in 50-70% of cases, moderate symptoms in 20-30% of cases, and severe symptoms in 10-15% of cases.
Beyond true allergic reactions, some people may be sensitive to the “non-digestible” sugars and fiber in soy. These components can cause abdominal bloating and gas, just like the sugars and fibers in most beans and just like the lactose in milk. Such symptoms are generally reduced, if not eliminated, when people use highly refined soy protein isolates which are 90-92% soy protein and only 3-4% carbohydrate (fiber plus simple and complex sugars and starches).
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