New research led by Lisa Ceglia of Tufts University School of Medicine and the Jean Mayer USDA Human Nutrition Center on Research Center on Aging (HNRCA), with colleagues including Bess Dawson-Hughes, examined whether protein supplements help preserve muscle strength in older adults. The randomized clinical trial enrolled 141 people aged 65 and over from the greater Boston area and lasted 24 weeks.
Participants took capsules containing whey powder or a placebo. Whey, derived from milk, is rich in the amino acid leucine, which can activate muscle-growth pathways. To test a separate idea, researchers also gave potassium bicarbonate, an antacid component, to see if neutralizing body acid would protect muscle. Strength was assessed with several tests, including leg presses and a balance test.
The main result was clear: extra protein did not improve measured strength after 24 weeks, whether or not potassium bicarbonate was used, and findings were consistent for women and men. Despite this, some biological markers changed — participants excreted more acid and had higher levels of the muscle-building hormone IGF-1 — suggesting the body showed signs of readiness to build muscle. Ceglia said these findings were surprising and not fully understood; possible explanations include subtle muscle changes that the tests could not detect, or that additional protein must be combined with exercise to produce strength gains. The researchers note that some groups may still benefit from supplements, for example:
- people who recently started exercising more
- people who become malnourished after serious injury
For healthy older adults who already eat the recommended amount of protein, the study found no evidence that supplements alone will improve strength. Ceglia plans future work on exercise combined with protein and recommends resistance training as the most reliable way to improve strength and function.
Difficult words
- supplement — Extra nutrient taken to add to dietsupplements
- placebo — Inactive treatment used to compare effects
- leucine — An amino acid important for muscle growth
- antacid — Medication or substance that reduces stomach acid
- excrete — To remove waste or fluids from bodyexcreted
- malnourished — Not getting enough nutrients for good health
- randomize — To assign people to groups by chancerandomized
- resistance training — Exercise using weights to build muscle strength
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Why might protein supplements increase IGF-1 but not measured strength in older adults?
- How could combining exercise with protein change the study results?
- Would you recommend supplements or resistance training for healthy older adults? Why?
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