The habitual omission of breakfast, already linked to various potential health implications, and having late dinner, are each associated with another important risk — bone fracture, new research showed.

“Our study is the first to suggest that skipping breakfast and having a late dinner were independently associated with a higher risk of osteoporotic fracture, in addition to the conventional risk factors, using a large-scale claims database,” the authors reported in the study, published this month in the Journal of the Endocrine Society.

The findings are from a large cohort study evaluating lifestyle habits and fracture data from 927,130 participants, with a median age of 66.6 years, in a large Japanese health claims database.

Over a median follow-up of 2.6 years, overall, 28,196 major osteoporotic fractures occurred in the cohort, for an incidence rate of 10.8 fractures per 1000 person-years.

After adjustment for multivariate, conventional risk factors, the omission of breakfast was significantly associated with an increased risk of having a diagnosis of osteoporotic fracture, including the hip, distal forearm, vertebral, and humeral fractures (hazard ratio [HR], 1.18) as was having a late dinner (HR, 1.08).

The breakfast and dinner habits, along with smoking (HR, 1.11), had the strongest associations with osteoporotic fracture compared with other lifestyle habits, including exercise (HR, 0.99), adequate sleep (HR, 0.95), alcohol use (HR, 0.91), and having a fast gait (HR, 0.84).

Of note, participants reporting skipping breakfast and having late dinner represented the study’s youngest participants, with a median age of 52.3 years, whereas those who reported not skipping breakfast or having late dinner were the oldest, with a median age of 67.2 years.

Those who omitted breakfast and had late dinner also had the highest median BMI (23.7), whereas those who reported neither habit had the lowest median BMI, of 22.9.

Breakfast-Skippers Had Higher Rates of Other Unhealthy Lifestyle Habits

The breakfast skipping/late dinner group notably had other unhealthy lifestyle habits, including having the highest proportion of current smokers (42.6%) and daily drinkers (56.3%), and the lowest proportion of individuals with regular exercise habits (23.2%) and sufficient sleep (56.3%) compared with the other groups.

Previous research has suggested skipping breakfast and having late dinner to be linked to obesity, type 2 diabetes, and cardiovascular disease, and skipping breakfast has also been associated with lower bone mineral density and fracture risk.

However, the new study is the first to link late dinner habits to a higher risk for osteoporotic fracture.

With previous studies evaluating time-restricted eating showing a 12-hour eating window results in higher oxidative stress and lower insulin sensitivity compared with a 6-hour eating window, the authors speculated that “late dinners may contribute to elevated cortisol levels and oxidative stress, potentially affecting bone metabolism and contributing to the risk of osteoporosis.”

Of note, other studies have shown that those who skip breakfast have lower vitamin D and calcium intake and lower serum 25-hydroxyvitamin D levels than those who consume breakfast, suggesting that vitamin D deficiency due to a lack of breakfast intake may influence the increased risk for osteoporotic fractures, the authors said.

Considering the existing research, first author Hiroki Nakajima, MD, PhD, of the Department of Diabetes and Endocrinology at Nara Medical University in Kashihara, Japan, noted that “I was not surprised because previous studies have shown that [skipping breakfast] can affect bone mineral density.”

“By contrast, it was surprising that late dinner was harmful to bone health,” Nakajima told Medscape Medical News, adding that “it is easy to imagine it is also bad for obesity and diabetes.”

Theories of how the regular habit of having late dinner could have a role in fracture risk include that “late dinner can deteriorate quality of sleep and circadian rhythm, which is essential for maintaining bone health,” Nakajima explained.

While the study involved a Japanese cohort, Nakajima said the findings could apply to broad populations.

“Considering such mechanisms, the impact of unhealthy dietary habits may be universal across different races,” Nakajima said. “Of course, the magnitude of this impact may be influenced by factors such as dietary composition and genetic background.”

Furthermore, “these eating patterns often cluster with other adverse behaviors — such as smoking, low physical activity, and insufficient sleep, so it is important to maintain an awareness of gradually improving overall lifestyle habits, even little by little,” Nakajima said.

More Study Needed

Commenting on the research, Emma Billington, MD, an adjunct assistant professor at the Cumming School of Medicine, University of Calgary, in Alberta, Canada, noted that although many observational studies have linked healthy dietary patterns with bone mineral density and fracture risk benefits, “to my knowledge, this is the first large observational study demonstrating that the timing of meals might also be associated with fracture risk.”

While raising some complex questions, the findings suggest a possible link between meal timing and bone resorption, she speculated.

“As consuming a meal has been shown to suppress bone resorption markers (such as C-telopeptide), it could be hypothesized that longer fasting intervals between meals, and particularly before breakfast, might be associated with increased bone turnover,” said Billington, who is also an assessment physician and physician lead with the Alberta Medical Association.

“However, without more information about the nutrient intake of the population in this study, it is not possible to know whether the associations with fracture risk are due to the timing of the meals or perhaps related to different nutrient intake among those who frequently skip breakfast and/or eat a late dinner.”

Overall, “this is an interesting, hypothesis-generating study, although it will be important to confirm the findings in other populations and other large cohorts,” she said.

The study was funded by the Japan Ministry of Education, Culture, Sports, Science and Technology. The authors had no disclosures to report. Billington received a grant from the Dairy Farmers of Canada, with funding administered by the University of Calgary.