Diabetes, mealtimes, and heart health: What's the link?

• Researchers have found evidence that the time a person eats their food can affect their cardiovascular health.
• However, is there a connection between the specific types of food eaten at particular times of the day and cardiovascular health?
• In the present observational study, the researchers found that eating some foods at particular times of the day is linked to an increased risk of cardiovascular disease mortality in people with diabetes.

Mealtimes may impact cardiovascular health in people with diabetes, according to new research.

A new study, published in the Journal of Clinical Endocrinology & Metabolism, lays the groundwork for further research to confirm the findings and see if the association identified by the study authors is causal.

Diabetes and eating times

According to the Centers for Disease Control and Prevention (CDC), diabetes is a long-term disease that affects how a person is able to move sugar from the bloodstream into the cells of the body.

This movement of blood sugar is normally regulated by insulin. If a person’s body does not react to insulin properly, or if their body does not make enough insulin, then their blood sugar levels increase.

The National Institute of Diabetes and Digestive and Kidney Diseases notes that a person with diabetes is also at risk of other cardiovascular diseases such as heart disease or stroke.

Researchers have found that changing a person’s diet is a key way a person can prevent or delay the development of diabetes or better manage the disease.

In addition, researchers have also found evidence that for cardiovascular disease prevention, what matters is not only what a person eats but when they eat.

In the present study, the researchers wanted to go a step further and see if they could link the time of eating specific foods to increased cardiovascular risks for people with diabetes.

Medical News Today spoke to Dr. Wei Wei — of the Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin, China — and a corresponding author of the study.

“Chrono-nutrition, as an emerging field of nutritional research, aims to understand how meal times impact health.”

“In previous research, our team has found that in addition to the quantity and quality of food, consumption time of diet is also critical for diabetes patients. Diabetes people consuming more energy and macronutrients in the evening could damage their long-term survival.”

“Therefore, we further analyzed the effects of consumption time of food groups on health to help diabetes patients choose reasonable food and their optimal intake times,” said Dr. Wei.

Observational study

To do this, the researchers analyzed data from the United States National Health and Nutrition Examination Survey. The researchers looked at information from 4642 people with diabetes between the years 2003 to 2014.

The participants self-reported the types and times of food they ate for 2 nonconsecutive days. The researchers then linked this information to data on whether the participants went on to die of cardiovascular disease.

The researchers found some associations between the timing of eating specific foods and the risk of mortality from cardiovascular disease.

For example, they found that people who ate starchy vegetables such as potatoes in the morning, whole grain in the afternoon, darker vegetables — such as broccoli — and milk in the evening, and refrained from eating processed meats in the evening, had a lower risk of dying of cardiovascular disease.

Dr. Wei suggested there may be two factors that account for the observed findings.

“First, mechanistically, many gene expressions have their circadian rhythm, such as the glycolipid metabolism, [which] is higher in the morning, and melatonin synthesis, inflammatory and oxidative stress are higher in the evening. Hence, food intake-time should be in line with the corresponding metabolic rhythm.”

“Second, in addition to the natural circadian cycle, food is also a key factor in regulating the body’s circadian rhythm. And a rational food consumption could restore the rhythm disorder for diabetes.”

“Therefore, our results provide a better interpretation of why people should pay more attention to healthy rhythmic eating,” said Dr. Wei.

Confounding factors?

MNT spoke with Prof. Roy Taylor, Professor of Medicine and Metabolism at the Translational and Clinical Research Institute, Newcastle University, United Kingdom.

Prof. Taylor, who was not involved in the research, cautioned on the extent to which the data in the study supported the conclusion that changing the times of eating specific foods could reduce the cardiovascular risk for people with diabetes.

“This is a study of statistical associations, and the hard data are not straightforward. The paper presents no proof that changing to eat starch before noon affects a person’s risk of mortality — that can only be established by a controlled intervention study to test this change in eating.”

“The statistical associations reported will be confounded to some degree by the associations which were neither measured nor reported.”

“The statistical observations — which of course in themselves may be valid — require to be tested in a proper study before any clinically useful changes to eating can be determined,” said Prof. Taylor.

MNT also spoke with Dr. Kristen Brandt, a Senior Lecturer at the Human Nutrition Research Centre and a colleague of Prof. Taylor at Newcastle University.

Dr. Brandt agreed with Prof. Taylor that there are likely to be other confounding factors that the study authors have not accounted for. She also highlighted that the statistical power of the findings might be low due to the many possible associations the study authors tested for.

Dr. Brandt said much could be done to further develop the study.

“The appropriate next step is to carry out the same type of association analysis on several other similar datasets collected in other studies, preferably from different countries and food cultures. If various independent datasets consistently show the same type of effects, then the association is reproducible, not just a random coincidence.”

She also noted that it would be worthwhile to invest more targeted research to explore what may be causing the association between meal times and cardiovascular health in people with diabetes.

“This means to first design and carry out studies with relevant animal models, to investigate the mechanism of a biologically relevant effect; if this is successful, the next step is a human intervention study, where the confounders can be controlled by randomization.”

“If such a study — which is much more expensive than analysis of existing datasets — still shows an effect, then, and only then, it becomes relevant to consider how the new understanding can be implemented in practice, such as ‘individualized nutritional therapy plans,’” said Dr. Brandt.

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