Cocoa and blood pressure: an interview with Dr Karin Ried


It was recently announced that compounds in cocoa may help to reduce blood pressure. Please could you give a brief introduction to these compounds?

The compounds in cocoa responsible for blood pressure reduction are called flavanols or polyphenols. Flavanols are also found in green tea, dark berries or red wine.

How did your research into flavanols originate?

I have an interest in nutritional medicine and cardiovascular health. I have undertaken research also with other nutraceuticals, such as garlic and tomatoes and their effect on blood pressure and cholesterol.

What did your research into flavanols show?

Our review suggests flavanol-rich cocoa products to be effective in reducing blood pressure by 2-3 mm Hg in the short term. Epidemiological studies have linked even small reduction in blood pressure with beneficial effects on cardiovascular health.

What do you think was the mechanism behind flavanols helping to decrease blood pressure?

Flavanols are responsible for the formation of nitric oxide in the body, and nitric oxide causes blood vessel walls to relax and open wider, thereby reducing blood pressure.

How much cocoa/dark chocolate was needed to be consumed in order to see this decrease in blood pressure?

Participants in the 20 studies included in our review ate 3-100g of chocolate per day, or between one piece and one bar of chocolate containing 50-85% of cocoa.

Available data to date does not allow any recommendations regarding optimal dosage. Smaller dosages may be as effective as larger dosages. Larger daily intakes may not be as acceptable and practical/tolerable as smaller daily dosages.

Your research looked at dark chocolate and cocoa powder. Do you think there would be any reduction in blood pressure for people who ate milk or white chocolate?

Milk chocolate contains smaller amounts of cocoa, the active ingredient. The beneficial effects of cocoa may be slightly compromised by the sugar content. White chocolate does not contain any cocoa-flavanols.

The research you carried out was only a short-term study. Do you think that the same relationship would be found in a long-term study?

This remains to be determined. To date, no long term clinical trials have been conducted. Although epidemiological studies and mathematical modeling suggests long term cocoa consumption to be beneficial for cardiovascular health.

Do you have any plans to carry out a long-term study?

Yes, we are seeking funding to conduct a long term trial.

The question of whether chocolate is good or bad for us is often featured in the news. What are your thoughts on this question?

Moderate regular dosages of flavanol-rich cocoa products such as dark chocolate may be part of a comprehensive lifestyle plan to optimising blood pressure.

What impact do you think your research will have?

Our research contributes to the body of evidence of cocoa’s beneficial health effects. Chocolate is always a popular topic and seems to bring a smile on most people’s faces.

Where can readers find more information?

About Dr Karin Ried

PhD, MSc, GDPH, Cert Integrative Medicine


Dr Karin Ried is Research Director at the National Institute of Integrative Medicine.

Dr Ried has over 15 years experience in medical and public health research, and research interest in complementary and integrative medicine with a focus on nutritional health. Her research projects encompass nutritional medicine, cardiovascular health, bone health, gastrointestinal health, cancer, women's health, and Traditional Chinese Medicine.

Dr Ried received a Masters Degree in Chemistry (1993) and PhD from the University of Heidelberg, Germany in the Department of Human Molecular Genetics (1997). Her PhD and early postdoctoral work in human genetics at the Centre of Molecular Genetics, University of Adelaide, culminated in the discovery of various genes, one of which is involved in the development of cancer. In addition, Dr Ried completed a Graduate Diploma of Public Health at the University of Adelaide (2001), and a Certificate in Integrative Medicine at the University of Queensland (2009).

Dr Ried is a frequent speaker at national and international conferences. Her research has been featured on national radio, television, and in the print media in Australia and overseas. She has mentored and supervised 30 early career researchers, MBBS students, Honours, Masters and summer research scholarship students. Dr Ried has been the Program Manager of the government funded capacity building PHCRED program at the University of Adelaide since 2006 and at Flinders University in South Australia between 2003-06.

Research Interests

Dr Ried’s research interests include nutritional medicine in cardiovascular health, in particular the effects of garlic extract, tomato extract or chocolate and cocoa products on blood pressure and cholesterol. Other current projects include Traditional Chinese Herbal Medicine in the management of women’s health and fertility, and the effect of omega-3 supplementation on bone health. She is Chief Investigator on several competitive grants related to integrative nutritional medicine.

Dr Ried has extensive expertise in quantitative research, in particular in systematic reviews and meta-analyses, as well as in qualitative research, including questionnaire design and survey methods.

April Cashin-Garbutt

Written by

April Cashin-Garbutt

April graduated with a first-class honours degree in Natural Sciences from Pembroke College, University of Cambridge. During her time as Editor-in-Chief, News-Medical (2012-2017), she kickstarted the content production process and helped to grow the website readership to over 60 million visitors per year. Through interviewing global thought leaders in medicine and life sciences, including Nobel laureates, April developed a passion for neuroscience and now works at the Sainsbury Wellcome Centre for Neural Circuits and Behaviour, located within UCL.


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