If you’ve struggled with high blood pressure, then you know your first line of defense is your diet, but for obvious reasons it can be hard. And for many people it simply doesn’t work.
Now, a first-of-its-kind study has revealed a new way to reduce high blood pressure through nutrition. And it may be strong enough to lower blood pressure for folks who’ve tried other natural approaches without success.
In recent years many studies have suggested that flavanols can improve cardiovascular health, including blood pressure. But this has never been shown on a large scale, in a population study.
During a population study, epidemiologists ask people to fill in a food frequency questionnaire. This is called “self-reporting.” The researchers then check the answers against food composition tables to work out how much of a particular nutrient people are consuming and whether this nutrient is linked to a health benefit.
The Problem with Population Studies
People are known to virtue signal by claiming to eat more of what is considered healthy and less of what is unhealthy. What’s more, dietary habits change over time. People can't always remember what or how much they've been eating of certain foods. For these reasons, the information derived from population studies can be widely off the mark.
Food composition tables are equally misleading. There isn’t the same amount of vitamin C in every orange or the same amount of beta carotene in every carrot. Depending on the climate, soil, growing conditions, storage, preparation, and individual bioavailability, the amount of any nutrient we end up ingesting and utilizing from our food can vary by huge amounts.
A cup of tea, for instance, can contain between one mg and 600 mg of total flavanols. Yet in most analyses, this will be standardized to 125 mg per cup. This is obviously going to produce findings nobody can depend on.
These current methods of estimating consumption make it impossible to provide accurate guidance on how much to eat of the foods that contain these compounds, or even if they're worth eating at all. Something much more dependable is needed.
Brand-New Biomarkers Developed
A large group of scientists from the U.S. and Europe devised a method that doesn't rely on either self-reporting or composition tables. Instead, it measures how much of a specific nutrient is taken up in the body by examining a urine sample.
The team started by testing for flavanols.
This was no simple task because flavanols break down in the body to other molecules. It took the research team almost ten years to develop two biomarkers that could be measured. Then, all they had to do was put them to the test.
The researchers enrolled 24,152 men and women living in one area of England. All had urine samples measured for the biomarkers and blood pressure taken.
Significantly Lowers Blood Pressure
After taking into account a large number of factors that could affect the results, researchers found those people in the highest ten percent of biomarker-estimated flavanol intake had a systolic (top) pressure reading that was between 1.9 and 2.5 mmHg lower, and a diastolic (bottom) reading that was one percent lower than those in the lowest, ten percent group.
The association between flavanol intake and blood pressure was strongest among participants at higher risk of developing cardiovascular diseases, in particular, older participants and those with existing hypertension.
This study demonstrates for the first time in an objective way, and on a large scale, that flavanols can lower blood pressure. Lead author Gunter Kuhnie was extremely satisfied with the outcome of the trial.
"We are delighted to see that in our study, there was...a meaningful and significant association between flavanol consumption and lower blood pressure.
"The methodology of the study is of equal importance. This is one of the largest ever studies to use nutritional biomarkers to investigate bioactive compounds.
"In contrast to self-reported dietary data, nutritional biomarkers can address the huge variability in food composition. We can therefore confidently attribute the associations we observed to flavanol intake."
Which Flavanol-Rich Food is Best?
Flavanols are found in apples, berries, cocoa products, red wine, tea and leafy greens. But it's not yet possible to say how much of these dietary items to eat to provide a blood pressure-lowering benefit. The huge variability in the content of individual foods still remains, and the biomarker test is a long way from being included as part of a routine health assessment.
From their study the authors suggest those participants in the top ten percent of flavanol intake consumed between 146 and 618 mg/day. They admit that "further efforts are needed to obtain a more precise number if these data are expected to be used for the development of dietary recommendations..."
Prof. Kuhnie did suggest, however, that green or black tea was "the best source" of flavanols. For tea drinkers like me, this is wonderful news. But how much tea to drink is another question entirely.
"The problem is," Prof. Kuhnie explained, "that people take their tea very differently. If you had a very strong tea, one or two cups a day would be enough. But if you have weak tea, you would need ten or twelve cups."
