ACSM and Soyfoods Association of North America recently hosted a webinar entitled Challenges for providing protein for the aging to support nutrition & health needs. The webinar covered the below learning objectives:
- Describe protein needs for older adults.
- Identify challenges that older adults face in meeting their proper protein requirements to maintain muscle mass and independence.
- Discuss protein choices in managing health and disease.
General Protein Questions
How many grams of complete protein are needed vs. incomplete? Do they need to be eaten in combination?
Protein needs are based on body weight (0.8g/kg body weight) with potential need to increase that amount due to activity (athletes) or inefficiency of metabolism (aging). To meet daily needs for maintenance and repair, all the essential amino acids must be consumed in appropriate amounts. Complete proteins provide all the essential amino acids in the appropriate amounts and are well digested. Incomplete proteins are lacking one or more amino acids and/or are not well digested.
Incomplete proteins, commonly from plant sources, can be consumed in combination to meet amino acid needs; a common example of this is pairing beans and rice. However, even when these sources are combined, they may not be equivalent to high-quality proteins such as soy, dairy, and eggs. Example of this concept in images at following resource.
Is the timing of intake of complementary proteins important? In other words do the complementary proteins need to be taken in at the same time or can they be spread apart?
There are nine essential amino acids, deemed essential because the body cannot make them. Adequate amounts of amino acids of an appropriate pattern must be provided in the diet to meet the demand for protein synthesis and other metabolic pathways to support maintenance and repair.
The body can only absorb a certain amount of protein at one time. So, if a person is consuming the majority of their protein at one meal, they may not be reaping the full benefits. To better meet needs and support muscle health and repair, it is recommended that one should spread protein intake out across the day, such as consuming 30g of protein at three meals or 18g of protein at 5 meals.
In addition, different proteins have different digestions rates and consumption of a blend of proteins can sustain delivery of amino acids to tissues. New research suggests combining proteins that have different absorption rates-such as soy protein, whey, and casein-can prolong delivery of amino acids to the muscle.
Could you differentiate different types of powdered protein: soy, whey, egg, peanut protein powder?
From a nutrition standpoint, these proteins differ in their protein quality, which takes into consideration the digestibility and amino acid composition of each protein, in reference to meeting needs for maintenance and repair. (See this comparison chart.) Soy, dairy (whey is a by-product of dairy processing, such as making yogurt) and egg are all high quality or complete sources of protein. Peanut protein has a significantly lower protein quality, meaning it lacks one or more amino acids and is poorly digested.
Why exactly is more protein consumption recommended for older adults who are ill?
Older adults lose muscle mass more rapidly than younger adults for many reasons, including a sedentary lifestyle, lower metabolic rates, and medications. Ill older adults lose muscle mass even more rapidly than healthy older adults. It is important that older adults consume enough protein to help maintain and rebuild muscle lost during aging and illness.
Can you recommend a few examples of optimal protein sources appropriate for the aging population who are following a vegan based diet?
ACSM recently published a blog on just this topic, comparing plant-based sources of protein. Not all protein is created the same. You evaluate protein's quality by looking at the "building blocks" of protein, or amino acids, making sure the foods you eat have the right balance of essential amino acids and seeing how well your body can digest and absorb them. The blog post compares different protein products as well as the quality of the source of proteins.
Soy protein is a high quality, complete plant protein that is comparable to high quality animal protein (e.g., beef, milk, eggs). Soy protein is unique in that it is the only complete source of vegetable protein widely available.
Protein Adjustments For Activity Levels
How would an increased activity level increase the protein recommendations?
Exercise plays a significant role in calculating the amount of protein that older adults should consume. The combination of exercise and protein ingestion has been shown to have a positive effect on muscle protein synthesis and skeletal muscle mass. In middle-aged and older-aged adults (50 years and older), muscle mass was preserved in individuals that had exercised (strength and aerobic) and met or exceeded the RDA (a).
Exercise in older adults does not have to be extreme, even moderate amounts of walking may impart a protective effect on muscle mass and metabolic health (b). Improvements in muscle mass and function most often occur in response to the combination of protein supplementation and exercise training (a, c, d).
It has been shown that if an older adult's habitual protein is already adequate (≥ 1.0 g/kg/day), providing even more protein may offer limited or no additional benefits on skeletal muscle mass and function (e,f). Thus, for all adults, to optimize the potential for muscle growth and maintenance of muscle mass, it is important to consume an adequate amount of high-quality protein at each meal in combination with daily physical activity.
a. Morris MS, Jacques PF. Total protein, animal protein and physical activity in relation to muscle mass in middle-aged and older Americans. Br J Nutr 2013;109:1294-303.
b. Breen L, Stokes KA, Churchward-Venne TA, Moore DR, Baker SK, Smith K, Atherton PJ, Phillips SM. Two weeks of reduced activity decreases leg lean mass and induces "anabolic resistance" of myofibrillar protein synthesis in healthy elderly. J Clin Endocrinol Metab 2013;98:2604-12.
c. Tieland M, Dirks ML, van der Zwaluw N, Verdijk LB, van de Rest O, de Groot LC, van Loon LJ. Protein supplementation increases muscle mass gain during prolonged resistance-type exercise training in frail elderly people: a randomized, double-blind, placebo-controlled trial. J Am Med Dir Assoc 2012;13:713-9.
d. Breen L, Phillips SM. Interactions between exercise and nutrition to prevent muscle waste during aging. Br J Clin Pharmacol 2013;75(3): 708-15.
e. Cermak NM, Res PT, de Groot LC, Saris WH, van Loon LJ. Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a meta-analysis. Am J Clin Nutr 2012;96:1454-64.
f. Verhoeven S, Vanschoonbeek K, Verdijk LB, Koopman R, Wodzig WK, Dendale P, van Loon LJ. Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men. Am J Clin Nutr 2009;89:1468-75
I work with many seniors and they are already exercising. Some want to take protein shakes. What is your opinion on seniors taking shakes?
It is important for seniors to meet their protein recommendations and shakes or smoothies are an easy way to add protein into the diet for older adults, especially for those with chewing and swallowing difficulties. There are two ways to incorporate protein into a shake. The first is to use supplement powders (whey, soy, pea, etc.). The second is to use whole foods.
Some whole foods that are high in protein and can be added include: greek yogurt, tofu, cottage cheese, seeds or nuts, peanut/soy butter, and oats. Flavoring can be added using fruits or vegetables and for extra liquid milk (dairy, soy, almond, etc) will add in even more protein. If smoothies/shakes are being used as a meal replacement it is important that it contains sufficient protein (20-30 g).
General Soy Questions
What age is considered "older adults"? And when does the benefit of adding soy to the diet becoming more important?
"Older adults" is usually referring to those who are 65 years and older. However, soy offers benefits to adults of all ages so I would recommend including soy into everyone's diet regardless of age.
Can you list some other sources for soy protein, outside of edamame? What are the best sources of soy protein?
Soymilk, tofu, tempeh, roasted soynuts, soynut butter, black soy beans, textured soy protein, textured vegetable protein, bean -based pasta, tofu "shirataki" noodles, soy crumbles, soy yogurt, protein bars - and the list keeps going. Soy is also the main component in many veggie burgers, veggie sausages, veggie hot dogs, and other meat alternatives.
I have read that consuming an excessive amount of soy products can have harmful effects on the natural hormone balance. What are your thoughts?
In general, consuming excessive amounts of most any food should be avoided. Typically, when an excessive consumption study is designed, it usually includes injection of large amounts of a substance in rodents. Often more of the substance than could ever be reasonably consumed by a human.
Soyfoods contain complex mixtures of proteins, fats, carbohydrates, and bio-active compounds such as soy isoflavones. These isoflavones are phytoestrogens with approximately 1/1,000th the biological activity of circulating human estrogens.(a) Phytoestrogens are part of the plant's natural defenses that act differently than hormones in humans. As humans are not rats, studies of isoflavones in rodents give different results, which have fostered myths surrounding the intake of soyfoods. Rats injected with large doses of isoflavones might experience problems that are not seen in human studies.
In humans, studies show soy isoflavones do not lower testosterone levels, may improve the health of arteries, prevent certain cancers including breast and prostate cancers, and reduce menopausal symptoms. (c)
a. Setchell KD. Phytoestrogens: the biochemistry, physiology, and implications for human health of soy isoflavones. Am J Clin Nutr 1998; 68:1333S-1346S.
b. Bai W, Wang C, Ren C. Intakes of total and individual flavonoids by US adults. Int J Food Sci Nutr. 2013 Sep 11.
c. Kang J, Badger T, et al. Non-isoflavone Phytochemicals in Soy and Their Health Effect. J. Agric. Food Chem. 2010, 58, 8119-8133.
Is there a relationship with soy intake and breast cancer?
Yes. The American Institute for Cancer Research reviewed the latest scientific evidence on soy and cancer in 2014 and released a position statement (a) that soyfoods are not only safe but "contain several key nutrients and phytochemicals studied for their cancer prevention properties." The American Cancer Society reiterates this statement and supports soyfood consumption.(b) Studies have shown that women who eat soyfoods regularly are less likely to develop breast cancer compared to those who don't. Researchers at the University of Southern California found (c) women averaging one cup of soymilk or about half a cup of tofu daily are 32% less likely to develop breast cancer and have a 29% decreased risk of death, compared with women who ate little or no soyfoods.
Eating soyfoods early in life may be one of the factors that explains why Asian women have lower breast cancer rates, as low as 1/5 that of Western women. (d) Early intake of soyfoods may promote healthy breast tissue development. (e)
b. McCullough, Marji. The Bottom Line on Soy and Breast Cancer Risk. August 2, 2012. "Even though animal studies have shown mixed effects on breast cancer with soy supplements, studies in humans have not shown harm from eating soy foods. Moderate consumption of soy foods appears safe for both breast cancer survivors and the general population, and may even lower breast cancer risk. … So, enjoy your occasional tofu stir-fry or tofu burger - they are unlikely to increase your risk of breast cancer and, on balance, are some of the healthier foods you can eat!"
c. Wu AH, Yu MC, Tseng CC, Pike MC. Epidemiology of soy exposures and breast cancer risk. Br J Cancer. 2008;98:9-14.
d. Lee SA, Shu XO, Li H, Yang G, Cai H, Wen W, Ji B-T, Gao J, Gao YT, Zheng W. Adolescent and adult soy food intake and breast cancer risk: results from the Shanghai Women's Health Study. Am J Clin Nutr. 2009;89:1920-6.
e. Gilchrist JM, Moore MB, Andres A, Estroff JA, Badger TM.Ultrasonographic patterns of reproductive organs in infants fed soy formula: Comparisons to infants fed breast milk and milk formula. J Pediatrics. 2010;156(2):215-220.
Can you address the issue of isoflavones and their possible effect on estrogen metabolism, especially in the significant population of peri or post menopausal women or with, or with risk of, estrogen receptor positive carcinoma of the breast where a decrease in estrogens is recommended?
The European Food Safety Authority - which is the food regulatory arm of the European Union, much like the Food & Drug Administration (FDA) in the U.S. - conducted a comprehensive review of the available scientific evidence and released a report in 2015 that says there is "no indication that isoflavones at levels typically found in food supplements cause harm to post-menopausal women." Reviewing 43 human studies and 62 animal studies, the Panel on Food Additives concluded it is safe for post-menopausal women to consume soy isoflavones daily without concern of breast and uterine cancer and thyroid function. Specifically the panel concluded that:
- Interventional human trials and population studies did not suggest an association between exposure to isoflavone and adverse effects in mammary glands in post-menopausal women.
- No reported statistical changes in endometrial thickness and no cases of endometrial carcinoma/uterine cancer in post-menopausal women taking up to 150 mg of isoflavone supplement for up to 2.5 years compared to controls.
- In controlled, randomized studies, there was no clinically relevant effect on thyroid function detected in post-menopausal women with normal thyroid function.
What is the effect of soy intake upon thyroid function in hypothyroid individuals?
The thyroid produces hormones to help regulate your body's metabolism and calcium levels. Foods containing goitrogens - soybeans, pine nuts, millet, strawberries, spinach, bamboo shoots, sweet potatoes, broccoli, bok choy, brussel sprouts, cabbage, canola, cauliflower, radishes, mustard greens, and turnips - get a bad rap because they can block some iodine absorption and may interfere with thyroid function. (For a good article explaining why "antinutrients" shouldn't be avoided, click here.) For an individual with hypothyroid, the timing of consuming these foods should be discussed with a doctor as they could impact the absorption of their medication.
Healthy individuals do not need to avoid goitrogen containing foods. A clinical review (a) found that people with healthy thyroid function who ate soy were not at increased risk for thyroid problems. Findings of the Cancer Prevention Institute of California's Bay Area Thyroid Cancer Study (b) found that women who consumed the most soyfoods, both traditional and modern, have about half the risk of thyroid cancer compared to those who consumed the least.
a. Messina M, Redmond G. Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature. Thyroid. 2006;16:249-258.
b. Horn-Ross PL, Hoggatt KJ, Lee MM. Phytoestrogens and thyroid cancer risk: the San Francisco Bay Area thyroid cancer study. Cancer Epidemiol Biomarkers Prev. 2002 Jan;11(1):43-9.
Rachel Deer, Ph.D. is a research fellow at the University of Texas Medical Branch in Galveston, Texas. She is also an associate scholar of the Claude D. Pepper OAIC in the Sealy Center on Aging at UTMB. Currently, she is overseeing four studies on the Acute Care for Elders Unit at Jennie Sealy Hospital. In this role she manages clinical trials using intervention strategies to accelerate recovery and improve health outcomes among older hospitalized patients. She is also interested in determining the prevalence and role of malnutrition and sarcopenia during hospitalization in geriatric patients.