Soy vs. Whey:  Protein Quality Matters, Especially to Your Thyroid and Muscles

Tuesday, September 18, 2012
By: Byron J. Richards,
Board Certified Clinical Nutritionist

Quality of protein is a hot topic of debate; whether you consume soy or whey protein makes a considerable difference in your health.

In the past, the idea of quality protein has been attributed to whether or not a protein source provided all eight essential amino acids, which you must get from your diet. Whey protein (a by-product of cheese production), casein (the most common dairy protein, but not found in whey), and soy protein are all examples of complete proteins. According to 20th century theory, these should all be high quality proteins. This idea has enabled the purveyors of cheap soy products to flourish in America. 

Unfortunately, soy falls short of being a high quality protein; it may even pose health risks, especially to your thyroid. Alternatively, fine quality whey protein isolates are proving themselves as a nutritional powerhouse; they significantly improve muscle health and thereby contribute to a better metabolic rate.

Several recent studies in elderly men show that whey protein is effective for rejuvenating muscles. As a superior protein it can make a large difference in maintaining muscle, and thus quality of health - this is a very important longevity principle. Such benefit is of specific value to improve thyroid function, especially when compared to soy protein, which has a disturbing anti-thyroid history.

Muscles and Aging

During aging the rate that muscles break down tends to exceed the rate of protein synthesis that is needed to produce new muscle fibers. Even exercise in older individuals does not stimulate new muscle protein synthesis as well as it does in a younger person. 

Finding strategies to boost the efficiency of new muscle fiber formation can have a large impact on quality of health as well as mobility in an aging population. Several new studies indicate that whey protein has a huge advantage, especially over soy protein, which appears to do little if anything to actually help. 

Such findings necessitate that we redefine what is meant by quality protein. Quality protein provides more than an array of amino acids within the food. Other factors are involved and have an influence on how those amino acids are actually used. 

Exercise is also important to the utilization of protein. Your body will not build muscle unless you use your muscles. This is because muscles require energy; they are metabolically expensive to maintain.  As you age your body conserves energy as best it can. In this context muscles that are not in use will be broken down to help conserve energy. 

Demanding physical activity implies you use your muscles, which in turn encourages your body to keep them. Resistance training (weight lifting) is one way to stimulate muscles to build new fibers out of protein. The protein studies referred to in this article combine resistance training with various types of protein to determine the best combination to compensate for aging.

Soy Protein as a Food Choice and Thyroid Disrupter

Your general dietary protein intake should be from a wide variety of food choices; legumes are a good choice. However, your body is most accustomed to the legumes of your heritage. This means soy is likely best for people of Asian decent, whereas different legumes are more suitable for others. Furthermore, traditional preparations of soy (like Miso) often involve fermenting the soy, which will change the digestibility of the protein. Yet, in America today, many people are eating large amounts of unfermented soy protein and soy protein powders. 

Soy is being promoted as part of a low fat diet, especially to women. Soy contains phyto-estrogen properties, causing it to interact with sex hormones. Even modest soy intake in men can drastically depress sperm count. It is being marketed to help women with hormonal issues and breast cancer prevention, though the data on soy in these regards is highly controversial. Conversely, data indicates that soy protein can cause breast cancer growth. Worse, some women are genetically susceptible to getting breast cancer from soy, rather than it being protective.

Soy is clearly an endocrine disrupter. It has the potential to cause cancer, and to have unpredictable effects on metabolism. This topic is hotly debated in current literature; it’s a David vs. Goliath debate. On the David side are researchers pointing out the obvious problems of soy intake. On the Goliath side is Big Agriculture, a billion dollar industry using “scientific” literature to concoct a favorable marketing campaign for soy intake in American women of the baby boomer generation.

This issue is made even more complex by the fact that a majority of the soy crop is now genetically altered; toxins are spliced into the essence of the DNA of the food. I consider such GMO Genetically Modified Organism. Refers to an organism whose genetic material has been altered using various engineering techniques such as recombinant DHA technology. May be used in general terms to refer to Genetically Modified Foods (GMFs) food unsafe to eat on a regular basis. Thank Monsanto and Cargill for trying to cram it down your throat. I explain this issue in great detail in my article, Monsanto’s GMO Genetically Modified Organism. Refers to an organism whose genetic material has been altered using various engineering techniques such as recombinant DHA technology. May be used in general terms to refer to Genetically Modified Foods (GMFs) Perversion of Food.

Of particular interest to the aging process is the fact that soy protein has the potential to disrupt thyroid function. It is known that soy protein, especially as intake increases, reduces the functionality of an enzyme in the thyroid gland called thyroid peroxidase. This enzyme is needed to form thyroid hormone by assisting iodine to combine with tyrosine.  Higher intake of soy can significantly reduce its activity (up to 80 percent in animal studies). 

The risk for a thyroid depressing interaction with soy increases with the amount of soy consumed. It also increases if you are lacking iodine or have pre-existing metabolic issues, which are typical in overweight people. It is especially dangerous in people with existing hypothyroid conditions. Adverse interactions of soy protein in humans are known to induce goiter. Adverse changes in thyroid hormone status in children are directly related to the amount of soy consumed.

A Japanese study gave 30 grams of soy protein per day to 37 people. This level of soy intake caused TSH scores to rise, although they remained in the normal range. However, any rise in TSH indicates thyroid stress and poor metabolism of the hormone within one’s body. Stunningly, poor metabolic symptoms (tiredness, constipation, etc.) and even some goiters appeared in half of the people who consumed this amount of soy for three months, especially in older individuals. The authors concluded that “excessive soybean ingestion for a certain duration might suppress thyroid function and cause goiters in healthy people, especially elderly subjects.” 

This level of soy intake would readily occur in people trying to boost their protein intake with a soy protein drink or in vegetarians trying to boost their general protein intake based on food choices of their diet. Disrupting thyroid function will have adverse consequences to muscle fitness and muscle health, reflected by the tiredness and lack of energy in muscles. Such an outcome would speed age-associated decline, a type of slow and progressive poisoning of metabolism over time.

Soy vs. Whey

A recent study compared soy protein to whey protein in terms of its ability to actually help muscles make new muscle fibers when elderly people performed weight lifting as part of their lifestyle.

Earlier, these researchers had proved that 20 grams of whey protein intake at one time was the optimal meal fortification for a younger person to get new muscle fiber response from exercise. More than 20 grams of whey protein provided no additional muscle benefit, in terms of the rate of new protein synthesis.

In the new study researchers tested doses of 20 grams of whey, 40 grams of whey, 20 grams of soy, and 40 grams of soy. They were interested in finding out whether the type, as well as the dose of protein made a difference in older people.

They found that soy protein was useless in any dose in terms of providing a boost in new muscle fiber synthesis in response to exercise. They found that 20 grams of whey protein could boost new muscle fiber formation in response to exercise. They also found it helped muscle fiber formation in muscles that were not exercised! And unlike the more youthful test group, a serving of 40 grams of whey protein was even better than 20. This means that whey protein, especially at higher doses, helped compensate for the condition of aged muscles.

The researchers conducted another study in elderly men comparing 20 grams of whey protein to 20 grams of casein protein (typical dairy protein). They found that whey protein increased the stimulation of new muscle fibers 65 percent better than casein, in both unexercised and exercised muscles.

Why Whey Protein Helps Muscles

Since whey, casein, and soy are all considered complete proteins, it is clear that whey protein possesses other attributes that differentiate its quality status as superior. While defining these differences is not yet fully understood, the initial research is pointing to several important facts.

Whey protein is very easy to absorb, compared to casein and soy. This causes a higher concentration of amino acids to reach muscles more quickly, contributing to the muscle rejuvenating properties of whey. This appears to be an important issue in “waking up” older muscles.

It is specifically important for the amino acid Building blocks of peptides and protein and have multiple roles of function in life including muscle function, growth, detoxification and metabolic pathways, and neurotransmitter function. leucine to signal muscle synthesis into action.  Leucine not only helps build muscle as a raw material, but also acts as a manager of muscles. In older muscles it takes more leucine to activate the muscle to build new muscle fibers out of protein. Whey contains 12 percent leucine, compared to eight percent in soy.

This new information is showing that whey protein stands above other forms of protein in helping to compensate for aging and maintain better muscle rejuvenation. It can be used as a tool to help activate muscles, in doses ranging from 20 grams to 40 grams at a time. A higher dose works better in an older person.

Any improvement in muscle fitness from exercise and protein intake means a corresponding improvement in thyroid function. One of the final end points of thyroid metabolism is your muscles. It is correct to assume that if you improve thyroid, your muscles will improve. However, it is even more correct to know that if you improve your muscles, you automatically improve your thyroid. While this is a bit of a chicken and egg scenario, the new science is favoring muscle fitness as a determining factor of thyroid health. 

This is similar to the idea that thyroid problems cause weight gain. Yes, that does happen. However, the new science is proving that weight gain is a main causative factor that disrupts thyroid function; weight gain like a punch your thyroid gland’s nose.

The take-home message is that if you can improve your fitness and lose weight in a healthy way you will do far more to actually improve the health of your thyroid than any prescription for thyroid medication will ever do for you.

I suggest a serving of whey protein (20 – 40 grams) as a smoothie in the morning, which will help with morning exercise as well as general activation of muscles for your daily activities. Use whey protein at any meal, especially before or after exercise, to boost general protein intake and muscle tissue formation, as desired. In a healthy and varied diet it is one of many types of protein you should consume.

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