Drinking this may offset unhealthy eating during stressful times: study

By Stephen Beech

Green tea and cocoa can protect from the negative effects of fatty foods when people are stressed, according to a new study.

Researchers from the University of Birmingham found that a flavanol-rich drink can protect the body against stress - even after eating high-fat dishes.

They say food choices made during periods of stress can influence the effect of stress on our cardiovascular health.

For example, the team previously found that high-fat foods can negatively affect vascular function and oxygen delivery to the brain, while flavanol compounds found in green tea and cocoa can protect vascular function during periods of everyday stress.

Now, in a new study, the same research team has found that drinking cocoa high in flavanols in combination with a fatty meal can counteract some of the impacts of high-fat food and protect the vascular system from stress.

Lead author Dr. Catarina Rendeiro, Assistant Professor in Nutritional Sciences, said: “We know that when people are stressed, they tend to gravitate towards high-fat foods.

"We have previously shown that fatty food can impair the body’s vascular recovery from stress.

"In this study, we wanted to see if adding a high-flavanol food to the fatty meal would alleviate the negative impact of stress in the body”

Study first author Rosalind Baynham, a research fellow, said: “Flavanols are a type of compound that occur in different fruits, vegetables, tea and nuts including berries and unprocessed cocoa.

"Flavanols are known to have health benefits, particularly for regulating blood pressure and protecting cardiovascular health.

“We took a group of young healthy adults and gave them two butter croissants with 10g salted butter, 1.5 slices of cheddar cheese and 250ml whole milk as breakfast, and either a high-flavanol cocoa or a low-flavanol cocoa drink.

"Following a rest period, we asked the participants to complete a mental maths test which increased in speed for eight minutes, alerting them when they got an answer wrong.

"During the eight-minute rest period and eight-minute mental maths test, we measured forearm blood flow, cardiovascular activity and prefrontal cortex (PFC) tissue oxygenation.

"We also measured vascular function using Brachial Flow-mediated dilatation (FMD), which is a prognostic measure for future risk of cardiovascular disease.

"This stress task-induced significant increases in heart rate and blood pressure, similar to the stress you may encounter in daily life.”

The cocoa drinks were prepared by dissolving 12g of cocoa powder into 250ml of whole milk.

The low-flavanol powder was an alkalized cocoa powder that was processed to reduce total flavanols to 5.6mg per serving; and the high-flavanol cocoa powder was a non-alkalized powder, delivering 695mg total flavanols per serving.

Alkalization is a process often employed in chocolate making to enhance flavor, but it reduces the amount of flavanols.

The findings, published in the journal Food and Function, showed that consuming high-fat foods with the low-flavanol drink when mentally stressed reduced vascular function,(by 1.29% FMD, and lasted up to 90 minutes after the stressful event was over.

The study also showed that the cocoa drink high in flavanols was "effective" at preventing the decline in vascular function following stress and fat consumption.

Brachial flow-mediated dilatation was "significantly higher£ following high-flavanol cocoa compared to low-flavanol cocoa 30 and 90 minutes after the stressful period.

Dr. Rendeiro added: “This research shows that drinking or eating a food high in flavanols can be used as a strategy to mitigate some of the impact of poorer food choices on the vascular system.

"This can help us make more informed decisions about what we eat and drink during stressful periods.”

She said that people should look for a minimally processed cocoa powder when shopping, while green tea, black tea and berries also give a higher dose of flavanols.

Recently published guidelines for flavanol intake recommend between 400 to 600 mg/day, which can be achieved, for example, by drinking two cups of black or green tea, or a combination of berries, apples and high-quality cocoa.

Study co-author Professor Jet Veldhuijzen van Zanten said: “Modern life is stressful and the impact of stress on our health and the economy has been well documented, so any changes we can make to protect ourselves from some of the symptoms of stress is positive."

She added: "For those who tend to reach for a treat when stressed or depend on convenient food because they work high-pressure jobs or are time-poor, incorporating some of these small changes could make a real difference.”