Megumi Tsubota-Utsugi of the National Institute of Health and Nutrition in Japan, and her colleagues in Tohoku University and Teikyo University, said due to increasing life expectancies in many countries, increasing numbers of elderly people are living with functional decline, such as declines in memory and problem solving as well as eating, bathing and dressing.
The researchers analyzed data of 1,007 individuals with an average age of 67.4 years who completed food questionnaires at the start of the study and seven years later.
Participants were divided into four groups according to their intake levels of total, animal, and plant protein. Tests of higher-level functional capacity included social and intellectual aspects as well as measures related to activities of daily living.
The study, published in the Journal of the American Geriatrics Society, found men in the highest quarter of animal protein intake had a 39 percent decreased chance of experiencing higher-level functional decline than those in the lowest quarter of protein consumption, but these associations were not seen in women.
No consistent association was observed between plant protein intake and future higher-level functional decline in either sex, the researchers said.
"Identifying nutritional factors that contribute to maintaining higher-level functional capacity is important for prevention of future deterioration of activities of daily living," Tsubota-Utsugi said in a statement.
"Along with other modifiable health behaviors, a diet rich in protein may help older adults maintain their functional capacity."
Research suggests that as people age, their ability to absorb or process protein may decline and it might be needed to compensate for this loss and increase protein requirements as people age, Tsubota-Utsugi said.