Can consuming cocoa help lower risk?

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Scientists have observed positive health effects from cocoa consumption, especially on heart health. Emilija Manevska/Getty Images
  • Consuming cocoa extract or very dark chocolate was shown to reduce several cardiovascular risk factors in a new meta-study, a study of other studies.
  • Cocoa consumption appeared to lower blood pressure overall, as well as bad cholesterol and blood sugar.
  • However, it did not seem to affect body weight or a primary biomarker of diabetes.
  • Various foods, such as cocoa, can promote heart health, though experts say an overall healthy diet is more effective at reducing cardiovascular disease.

A new meta-study of random controlled trials looks at the effect of consuming cocoa on cardiovascular disease risk factors.

Cocoa use was associated with varying degrees of improvement in total cholesterol and LDL (“bad”) cholesterol, systolic and diastolic blood pressure, and fasting blood glucose.

All of these are risk factors for heart or cardiovascular disease.

The researchers also found that cocoa consumption showed no effects on body weight, body mass index (BMI), waist circumference, triglycerides, “good” HDL cholesterol, and HbA1c, an important biomarker of diabetes.

The meta-study analyzed 31 randomized, controlled trials that tracked the above risk factors. The trials that qualified for analysis involved a combined 1,986 participants. Together, the intervention group included 1,110 participants who consumed either cocoa extract or dark chocolate with a 70% or higher cocoa content for at least four weeks. The control group involved 876 participants who consumed a placebo or white or milk chocolate containing less than 70% cocoa.

Individuals who qualified for the trials were all 18 or older. Of the 31 studies analyzed, four only included older adults, and five included only younger adults.

The majority of the studies involved participants with one or more health conditions, including metabolic syndrome (3), dyslipidemia (4), pre-hypertension or hypertension (2), excess weight (4), type 2 diabetes (7), and insulin resistance (1). The remaining 13 studies included only healthy participants with no known confounding CVD risk factors.

The analysis revealed, on average:

  • an 8.35 mg/dL reduction in overall cholesterol
  • a 9.47 mg/dL reduction in LDL cholesterol
  • a 4.91 mg/dL lowering of fasting blood glucose
  • a 2.52 mmHg reduction in systolic blood pressure
  • a 1.58 mmHg lowering of diastolic blood pressure.

The study is published in MDPI.

In the U.S., heart disease is the leading cause of death across all population categories, accounting for one in every five fatalities in 2021, according to the U.S. Centers for Disease Control. It strikes women, men, and every ethnic and racial group.

Every 33 seconds, someone in the U.S. dies of cardiovascular disease.

Diet is strongly implicated in CVD. The American Heart Association stresses the importance of a lifetime of good nutrition as a strong defense against heart problems.

There has been interest in identifying especially heart-healthy foods. Among these is cocoa due to the beneficial compounds it contains.

“Cocoa is a good source of catechins and other polyphenolic compounds like flavanols known for their antioxidant and anti-inflammatory properties, which can support cardiovascular health,” said Michelle Routhenstein, MS, RD, CDCES, preventive cardiology dietitian at EntirelyNourished.com, who was not involved in the new study.

“Cocoa is rich in flavonoids,” explained Routhenstein, “including epicatechin, which is a compound that helps to support nitric oxide-rich pools in the body which help to support heart and blood vessel health.”

Jayne Morgan, MD, cardiologist and the Executive Director of Health and Community Education at the Piedmont Healthcare Corporation in Atlanta, GA listed other heart-healthy foods: “Fatty fish, olive oil, nuts, berries, nuts, beans, green leafy vegetables, whole grains.”

Nonetheless, Routhenstein described the strongest prescription for heart health:

“A nutrient-sufficient, diverse diet including fruits, vegetables, fatty fish, nuts, lean protein, and whole grains provides a broader range of nutrients and protective compounds against cardiovascular disease.”

It is important, therefore, to consider cocoa “as part of a broader heart-healthy diet rather than a standalone protective measure against CVD,” said Routhenstein.

She suggested that for someone with a sweet tooth, “enjoying a square of [at least] 70% dark chocolate with berries, or adding cocoa powder into a hot beverage can serve as a satisfying and health-conscious evening treat.”

Routhenstein cautioned, however, that consuming excess chocolate of any kind, including dark chocolate, “can lead to high sugar and saturated fat intake which can negatively impact heart health, so the amount matters.”

“Moreover, caution should still be exercised with pregnancy,” said Morgan of too much chocolate. Though some research suggests potential benefits in moderation, pregnant individuals should be especially mindful of chocolate’s added sugar and caffeine content.

Morgan said, “even a 2.52 mmHg reduction in systolic blood pressure and 1.58 mmHg reduction for diastolic blood pressure is a positive.”

At the same time, she expressed concern over both the varying amounts of cocoa consumed and the unclear sources of that cocoa.

She pointed out that the amounts of cocoa participants ingested varied widely: from 1.4 g per day to 50 g per day.

“Further,” said Morgan, “multiple sources of cocoa, from beverages to bars to candy, etc. — with varying amounts of other ingredients such as milk and sugar — create a large heterogeneity to the population.”

This also raises the issue of inconsistencies in the cocoa manufacturing processes encompassed in the studies.

Routhenstein noted, “It is important to note that the availability of epicatechin in cocoa products can be affected by processing and storage conditions, as it is sensitive to heat and can degrade if not carefully handled during manufacturing.”

The meta-study found no effect of cocoa on a diabetes’ marker, HbA1c, although it did appear to provide a beneficial drop in blood sugar.

Morgan described the improvement in blood sugar as “a reflection of the level of control of diabetes and blood sugar in the body. Persistent high levels of blood glucose can damage blood vessels of the heart as well as elsewhere in the body, leading to peripheral vascular disease.”

As for HbA1c, said Morgan, longer-duration studies are needed to draw conclusions about cocoa and diabetes.

“Diabetes is a risk factor for CVD since it heightens the risk of atherosclerotic development that increases the risk of a heart attack,” Morgan said. “Further, diabetes is associated with chronic inflammation, a cardiac risk factor, as well as obesity.”

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