A clinical trial led by endocrinologist Lisa Ceglia and colleagues tested whether extra protein protects muscle in older adults. The study, published in the American Journal of Clinical Nutrition, recruited 141 people aged 65 and above from the greater Boston area.
Participants were assigned to take capsules with whey powder or a placebo control for 24 weeks. Whey, made from milk, is high in the amino acid leucine, which can activate muscle growth pathways. The researchers also gave potassium bicarbonate, an antacid component, to test whether neutralizing body acid would protect muscle. Strength was measured with tests including leg presses and a balance test.
The main finding was unexpected: extra protein did not change participants' strength after 24 weeks, whether or not potassium bicarbonate was used, and results were the same for women and men. Some biological signs, such as higher IGF-1 and more acid excretion, suggested the body was ready to build muscle. Ceglia said the lack of strength gain is not fully understood and that protein may need to be combined with exercise to produce gains. She recommends resistance training as the most reliable method to improve strength and function.
Difficult words
- clinical trial — a research study that tests medical treatments
- endocrinologist — a doctor who treats hormone and metabolism problems
- placebo — a harmless pill with no active medicine
- leucine — an amino acid that helps start muscle growth
- potassium bicarbonate — a chemical used to reduce acid in the body
- resistance training — exercise that uses 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
- Based on the study, would you recommend protein supplements alone to an older person? Why or why not?
- Have you or someone you know done resistance training? What changes did you see?
- What are possible reasons the study found no strength gain from extra protein alone?
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