Effects of fermented milk intake and physical activity on the suppression of age-related decline in physical fitness among the elderly.

Physical deterioration in the elderly can lead to disability and mortality. Although the intake of fermented milk has been recently attracting attention as a proposed measure to prevent physical weakness, studies and findings are limited. Here, we investigated the effect of intake of fermented milk products on suppression of age-related decline in physical fitness through a long-term epidemiological study of community-dwelling elderly people who are capable of independent living. A retrospective analysis was conducted on 581 elderly people aged 65-92 years from the Nakanojo Study, with the addition of a 5-year prospective analysis on 240 elderlies. Subjects were arbitrarily grouped on the basis of questionnaire estimates of fermented milk products intake (<3 or ≥3 days/week) and pedometer/accelerometer-determined patterns of physical activity (<7,000 or ≥7,000 steps/day). After adjustment for potential confounders, the retrospective study showed that the group consuming fermented milk products ≥3 days/week showed significantly faster walking speeds than the <3 days/week group. The group taking ≥7,000 steps/day had a significantly faster walking speed than the group taking <7,000 steps/day. Those who did both walked the fastest, indicating an additive effect. Adding protein or energy intake as a covariate to the potential confounders found a correlation between the intake of fermented milk products and walking speed, suggesting that the effect of fermented milk products consumption is independent of nutritional intake status, due to the beneficial properties of bacteria included in fermented milk. The 5-year prospective study confirmed a clear relationship between the frequency of consumption of fermented milk products and the suppression of preferred walking speed decline. Our findings suggest that habitual intake of fermented milk contributes to the suppression of walking speed decline in elderly people.