Poor diet adherence, sleep disorders synergistically increases mortality risk

Key takeaways:

• Poor adherence to the Mediterranean diet plus the presence of sleep disorders impacted cardiovascular and all-cause mortality but not cancer mortality.
• It is the first study to confirm the interaction, researchers said.

Poor adherence to the Mediterranean diet combined with a presence of sleep disorders jointly increased the risk for all-cause and cardiovascular mortality, a recent study found.

According to Yongle Wang, MD, a researcher in the department of neurology at Shanxi Medical University in China, and colleagues, “there is a significant correlation between diet and sleep, affecting each other.”

“Inadequate and irregular sleep pattern may lead to overfeeding and poorer dietary structure,” they wrote in BMC Public Health. “Also, varied dietary habits, and food components can have an impact on sleep disorders/parameters.”

However, “given that diet and sleep can affect each other, it is unclear if lower adherence level to [a Mediterranean diet] can interact with sleep disorders for long-term mortality,” the researchers wrote.

To learn more, Wang and colleagues analyzed 2005 to 2014 data on 23,212 individuals from the National Health and Nutrition Examination Survey to determine whether there is a synergistic effect of Mediterranean diet adherence and sleep disorders on mortality risk.

The researchers assessed outcomes through a nine-point evaluation score known as the alternative Mediterranean (aMED) index, with higher scores indicating greater adherence.

When analyzed apart from sleep disorders, a lower aMED was linked to a higher risk for all-cause mortality (HR = 1.42; 95% CI, 1.20-1.67) and cardiovascular mortality (HR = 1.13, 95% CI, 1.05–1.51) compared with those with higher aMED.

Meanwhile, those with a lower aMED and a presence of sleep disorders had the greatest risk for all-cause mortality (HR = 2.16; 95% CI, 1.49-3.13) and cause-specific mortality (HR = 2.68; 95% CI, 1.58-4.54), confirming “for the first time that the combined presence of poor adherence to the [Mediterranean diet] and sleep disorders synergistically increases all-cause and cardiovascular mortality,” Wang and colleagues wrote.

Upon further investigation, the researchers found a significant interaction effect between aMED scores and sleep disorders on cardiovascular mortality but not all-cause or cancer mortality.

“Poor dietary patterns with high intake of sodium, carbohydrate, intake of excessive processed foods, and low intake of fruits and vegetables are key risk factors for long-term mortality, and cardiovascular events, cancer incidence may mediate the causal relationship between diet and mortality,” Wang and colleagues wrote.

The higher cardiovascular mortality risk in patients with sleep disorders and higher aMED scores “may be because the systemic inflammatory response is more active in the context of sleep disorders,” the researchers wrote. The lack of interaction on cancer mortality may be because “some cancer patients have comorbid cardiovascular diseases and there is a competing risk relationship between cardiovascular mortality and cancer mortality, leading to statistical bias,” they added.

The findings also revealed effects that food components had on mortality associations.

“Fruits, whole grains, legumes and alcohol consumption significantly interacted with sleep disorder for cardiovascular mortality,” Wang and colleagues wrote. “We also found that moderate alcohol consumption increased the risk of cardiovascular death in people with sleep disorders.”

Ultimately, “adherence to a [Mediterranean diet] with fruits, whole grains and legumes has positive implications for people with sleep disorders,” they concluded.