A study in New Zealand investigated the effect of kumara (a type of sweet potato) on infant sleep. Researchers found that infants fed standard kumara had fewer nighttime awakenings. Another group that received Kumara with resistant starch had a slight increase in daytime sleep, but also a tendency for nighttime sleep to become more problematic. The paper was published in nutritional neuroscience.
Kumara is the Māori name commonly used in New Zealand for the root vegetable sweet potato, scientifically known as sweet potato. sweet potato. It is an edible plant in the morning glory family, cultivated for its swollen starchy roots. In New Zealand, kumara is an important food item with deep historical and cultural significance for the Maori people.
The Polynesian ancestors of the Maori people brought kumara to New Zealand as a cultivated food plant around the 13th century. Because New Zealand is cooler than tropical Polynesia, growing kumara required careful agricultural techniques. Over time, kumara became one of the most important traditional crops in Māori horticulture. Today it is also a common food in the modern New Zealand diet. Kumara can be baked, boiled, roasted, mashed, and used in soups, stews, chips, salads, etc.
Study author Xiaoshi Fu and colleagues point out that kumara is a common and acceptable first food for infants in New Zealand. It has been recognized for its prebiotic effect, which is the ability to stimulate the growth and activity of beneficial intestinal bacteria. Kumara naturally contains resistant starch, a substance that can be fermented and utilized by the infant’s intestinal microorganisms. A healthy gut microbiome has been shown to produce chemicals that regulate sleep hormones, leading researchers to wonder if prebiotic foods could improve infants’ rest.
The authors conducted a study to examine the effects of standard kumara and kumara supplemented with resistant starch (extracted from green bananas) on sleep in infants in the early stages of complementary feeding (6-10 months). This study investigated how daily consumption of kumara affected infant sleep patterns as reported by caregivers and caregivers’ own sleep quality.
Study participants consisted of 281 healthy infants living in Auckland, New Zealand. To participate in the study, participants had to be 3 to 6 months old at the start, born after at least 32 weeks of gestation, and weigh at least 2.5 kg at birth.
Participants were randomly divided into three groups: two intervention groups and one control group. Infants in the control group received no intervention and were simply fed solid food according to New Zealand dietary guidelines. One of the intervention groups received standard freeze-dried Kumara powder, and the other group received Kumara powder supplemented with resistant starch. Both intervention groups also received standard solid food.
This study was double-blind. That is, caregivers in the two intervention groups did not know which specific products they were receiving. The intervention product was given to caregivers in 5-gram sachets to be consumed daily for 4 months, beginning with the introduction of solid foods and until the infant reached approximately 10 months of age. The study authors tracked adherence to the intervention through intake records completed by caregivers along with monthly questionnaires.
Infant and caregiver sleep information was collected at the beginning of the study (before the introduction of solids), during the second month of complementary feeding, and during the fourth month of complementary feeding. Caregivers completed an assessment of their infant’s sleep (Infant Sleep Brief Questionnaire) and their own sleep quality (PROMIS Sleep Disturbances and Sleep-Related Disorders Scale).
The results showed that compared to the control group, infants fed standard kumara had significantly fewer nighttime awakenings by the end of 4 months. They didn’t necessarily wake up less often, but they settled into sleep much more quickly.
Conversely, the group of infants fed Kumara powder with resistant starch had a slight increase in daytime sleep time at 2 months of age. However, caregivers in this group also reported that they were more likely to have trouble sleeping at night, and that their infants were more likely to be awake for more than an hour at a time during the night. Researchers believe this may be because long naps during the day undermined the baby’s desire to sleep at night, or because the high doses of concentrated starch caused mild gastrointestinal discomfort.
Caregiver sleep outcomes did not differ significantly between the three groups.
“While kumara intake may reduce nighttime awakenings in infants, further studies incorporating objective sleep measurements and exploring the underlying mechanisms are needed,” the study authors concluded.
This study contributes to the scientific understanding of the effects of kumara consumption in infants. However, infant sleep assessments were based on caregivers’ subjective reports rather than objective data (e.g., electronic sleep trackers), leaving room for reporting bias to influence results. Additionally, the study began with generally healthy infants without severe sleep problems, so it is unlikely to show significant improvement.
The paper, “Effects of prebiotic intervention foods on caregiver-reported infant sleep and caregiver sleep quality during a supplementary feeding secondary analysis of a randomized controlled trial,” was authored by Xiaoxi Fu, Amy L. Lovell, Clare R. Wall, Teresa Gontijo De Castro, Yannan Jiang, Robyn L. Lawrence, Nisha Mahawar, and Barbara C. Galland.
