Peanut Butter Linked to Improved Muscle Power in Older Adults Without Weight Gain
A recent six-month study by Deakin University researchers suggests that daily consumption of peanut butter may improve lower-body muscle power and performance in older adults, specifically in sit-to-stand tests, without leading to weight gain. The findings, published in the Journal of Cachexia, Sarcopenia and Muscle, highlight a potential nutritional strategy to support muscle function in aging populations. Interestingly, the primary outcome measure of gait speed did not show a significant change.
Study Design and Participants
The Older Individuals after Nut Supplementation (COINS) study was a randomized controlled trial involving 120 community-dwelling adults, aged 65 to 89 years, who were living independently but considered at risk of falls.
The trial aimed to investigate the impact of daily peanut butter consumption on muscle function in older adults.
The trial, led by Associate Professor Sze-Yen Tan from Deakin University's Institute for Physical Activity and Nutrition (IPAN), randomly assigned participants into two groups:
- Peanut Butter Group: Consumed 43 grams of natural peanut butter daily, providing approximately 250 kilocalories, 10 grams of protein, and 20 grams of fat (primarily unsaturated).
- Control Group: Maintained their usual diet and lifestyle.
Of the 120 initial participants, 108 completed the six-month study period. The study was funded by The Peanut Institute in the United States.
Key Findings
Participants in the peanut butter group demonstrated several improvements in muscle function and specific physical assessments compared to the control group:
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Muscle Power and Sit-to-Stand Performance: The peanut butter group showed significant improvements in the five-time sit-to-stand (5STS) test, completing it an average of 1.2 seconds faster. Absolute muscle power increased by 22 watts, and relative muscle power increased by 0.27 watts per kilogram. These changes are considered potentially clinically meaningful, as improved muscle power is associated with better mobility, survival, and independence in older adults.
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Weight and Nutritional Intake: Despite increased energy, protein, and fat intake from the peanut butter, participants in this group did not experience significant weight gain. This suggests that daily consumption was well-tolerated without adverse effects on body weight.
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Gait Speed: The study's primary outcome measure, 4-meter gait speed, did not show a significant change in the peanut butter group compared to the control group.
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Safety: No major adverse events were reported during the trial, indicating the intervention was safe for participants.
Context and Implications
Age-related decline in muscle mass and strength, often accelerating after the age of 50, can reduce physical function and increase the risk of falls in individuals over 65. Nutritional strategies, particularly those focusing on protein intake, alongside resistance training, are recognized approaches to support healthy aging.
Peanut butter is noted for being naturally rich in protein, healthy fats, and antioxidants. These components are believed to contribute to reducing inflammation and muscle breakdown.
Researchers suggest that peanut butter could serve as an accessible, affordable, and palatable alternative to commercial oral nutrition supplements, which can be expensive.
Its smooth texture may also be advantageous for individuals with dental issues who find whole nuts challenging to consume, making it a practical dietary addition for many older adults.
Study Limitations
The researchers acknowledged several limitations of the study:
- Participants had a relatively high baseline protein intake and physical function, which may have influenced the observed benefits.
- Adherence to the intervention was self-reported, and participants were aware of their group allocation, potentially introducing an element of bias.
- The control group did not receive a placebo, which could affect the comparability between groups.
- Markers of inflammatory and oxidative stress were not measured, leaving potential biological mechanisms unexplored.
- The study did not adjust for multiple comparisons, which increases the risk of Type I error.
Future Research
Further research is planned to investigate whether consuming nuts in conjunction with resistance training could lead to broader improvements in physical function among older adults. The study also concluded that additional research is warranted, particularly among elderly individuals with lower muscle mass, reduced physical function, or those at risk of malnutrition.