October 21, 2020

expert reaction to study looking at dietary flavanol intake and blood pressure

A study, published in Scientific Reports, looked at dietary flavanol intake and blood pressure.

Dr Ada Garcia, Senior Lecturer in Public Health Nutrition, University of Glasgow, said:

“Tea, apples, berries, nuts and many other plant based foods contain flavanols, these are bioactive food components well known to be associated with lower risk factors for cardiovascular disease as shown in this large and very well conducted study.  The use of more precise ways to estimate if people have consumed specific flavanols in their diet is of great importance because up to now large studies have relied mostly on measurements based on self-report such as food diaries and these have several pitfalls.  Investing in research that provides better estimates of diet intake such as the surrogate biomarkers used in this study is a great step forward to a better understanding of the interplay between  diet and disease.”

Dr Ian Johnson, Nutrition researcher and Emeritus Fellow, Quadram Institute Bioscience, said:

“This is an important, high-quality investigation of some physiological effects of dietary flavonoids in a large UK population, freely consuming self-selected diets.  Its importance lies in the use of objective quantifiable biomarkers of flavonoid intake, as opposed to estimates based on what are necessarily imprecise measures of food intake and composition.  Using this approach, the authors have been able to show that systolic blood pressure was lower in participants consuming the highest quantities of flavonoids, compared to those consuming the lowest.  This is a potentially important observation because it is consistent with the growing evidence from randomised controlled human intervention trials showing that relatively high doses of certain flavonoids can exert a blood-pressure lowering effect.

“However, for all its strengths, this observational study cannot establish a causal effect of flavonoid intake at the population level.  The authors have done their best to control for other factors that might account for their results, but they are right to state that large-scale intervention trials will be required to test the hypothesis that the observed differences in blood pressure can be explained by differences in flavonoid intake.

“Finally, it should be noted that although statistically significant, the differences in blood pressure that have been observed are relatively small.  It can be argued that effects of this magnitude do have important beneficial effects against cardiovascular disease at the population level, but in this particular population there was no evidence of protective effects of flavonoid intake against the risks of cardiovascular disease, cardiovascular related death, or of all-cause mortality.”

‘Biomarker‑estimated flavan‑3‑ol intake is associated with lower blood pressure in cross‑sectional analysis in EPIC Norfolk’ by Javier I. Ottaviani et al. was published in Scientific Reports at 10.00am UK time on Wednesday 21 October 2020.

DOI: 10.1038/s41598-020-74863-7

Declared interests

Dr Ada Garcia: “No conflicts.”

Dr Ian Johnson: “No conflicts.”