Field Notes

Wearables Have Mixed Reliability for Tracking Calorie Balance

Accurate measures of individual energy intake, storage, and expenditure are important when assessing energy balance and its connections to food, nutrition, and health. Unfortunately, current measures of these energy components are challenging, often laborious, resource intensive, and marked by wide variability. A new study finds that commercial wearable devices such as Fitbit trackers provide robust estimates of energy expenditure compared with “gold-standard” methods, but results were mixed when used for energy storage and intake.

The findings were part of an article recently published in The Journal of Nutrition entitled “Commercial Devices Provide Estimates of Energy Balance With Varying Degrees of Validity in Free-Living Adults.” The research conducted in free-living healthy adults tracked their at-home daily activities, which are more representative of daily behaviors. 

The study finds “that commercial devices have differential reliability and validity for capturing the three components of the energy balance model. Energy expenditure estimates were the most robust overall, whereas energy storage were generally poor.”  The research calls for further study to understand measurement error and calibration of wearable devices as they offer an opportunity to measure population-level energy intake, storage, and expenditure patterns.

According to lead author Robin Shook, PhD, “These findings are a good representation of both the promise and concern of using consumer devices. The consumer devices were quite good in terms of free-living energy expenditure estimations but lacking for energy storage. Importantly, future work should focus on better understanding the measurement error of these consumer devices and using statistical techniques to account for this error.”

— Source: Institute for the Advancement of Food and Nutrition Sciences


Coffee, Tea Drinking May Be Associated With Reduced Stroke, Dementia Risk

Drinking coffee or tea may be associated with a lower risk of stroke and dementia, according to a study of healthy individuals aged 50 to 74 published in the open-access journal PLOS Medicine. Drinking coffee also was associated with a lower risk of poststroke dementia.

Strokes are life-threatening events which cause 10% of deaths globally. Dementia is a general term for symptoms related to decline in brain function and is a global health concern with a high economic and social burden. Poststroke dementia is a condition in which symptoms of dementia occur after a stroke.

Researchers from Tianjin Medical University in Tianjin, China, studied 365,682 participants from the UK Biobank, who were recruited between 2006 and 2010, and followed them until 2020. At the outset, participants self-reported their coffee and tea intake. Over the study period, 5,079 participants developed dementia and 10,053 experienced at least one stroke.

People who drank two to three cups of coffee, three to five cups of tea per day, or a combination of four to six cups of coffee and tea per day had the lowest incidence of stroke or dementia. Individuals who drank two to three cups of coffee and two to three cups of tea daily had a 32% lower risk of stroke (hazard ratio 0.68, 95% confidence interval 0.59–0.79; p<0.001) and a 28% lower risk of dementia (hazard ratio 0.72, 95% confidence interval 0.59–0.89; p=0.002) compared with those who drank neither coffee nor tea. Intake of coffee alone or in combination with tea also was associated with lower risk of poststroke dementia.

The UK Biobank reflects a relatively healthy sample relative to the general population, which could restrict the ability to generalize these associations. Also, relatively few people developed dementia or stroke, which can make it difficult to extrapolate rates accurately to larger populations. Finally, while it’s possible that coffee and tea consumption might be protective against stroke, dementia, and poststroke dementia, causality can’t be inferred from the associations.

The authors add, “Our findings suggested that moderate consumption of coffee and tea separately or in combination were associated with lower risk of stroke and dementia.”

— Source: PLOS