Effect of long-term consumption of Lacticaseibacillus paracasei strain Shirota-fermented milk on weight loss in the institutionalized oldest old: an exploratory study.

Older individuals with care needs and lower body mass indices (BMIs) are more likely to be malnourished. Unintentional weight loss, an indicator of malnutrition, significantly impacts the physical function and poor prognosis of older adults. This study aimed to explore the effects of long-term consumption of Lacticaseibacillus paracasei strain Shirota-fermented milk (LcFM) on body weight in the oldest old among nursing-home residents. In total, 118 participants in 21 nursing homes were recruited. Owing to its preliminary nature, randomization and blinding were not conducted, and subjects in the intervention (consuming LcFM daily for 12 months) and non-intervention groups were recruited separately from different nursing homes. Changes in body weight and the proportion of participants with ≥5% body-weight loss were assessed at 6 and 12 months. As intergroup discrepancies in care-needs levels were observed at baseline, a subgroup analysis by these levels was conducted to align baseline characteristics. In the mild care-needs level subgroup (long-term care level ≤2), the LcFM group had a significantly lower proportion of participants with ≥5% weight loss than the control group. Additionally, a subgroup analysis by BMI demonstrated that an effect of LcFM on body weight decline was observed only in the subgroup with a BMI <22 kg/m², which indicates malnutrition risk in older adults. In conclusion, long-term consumption of LcFM might reduce unintentional weight loss in the institutionalized oldest-old individuals who have a risk of malnutrition and have a mild care-needs level. To confirm these preliminary results, further well-designed randomized trials will be required (UMIN000036684).