January 18, 2011
Blueberries Keep Blood Pressure Down
Blueberries once a week to reduce your risk of high blood pressure by 10%. Strawberries help too but not as strongly.
High blood pressure – or hypertension – is one of the major cardiovascular diseases worldwide. It leads to stroke and heart disease and costs more than $300 billion each year. Around a quarter of the adult population is affected globally – including 10 million people in the UK and one in three US adults.
Published next month in the American Journal of Clinical Nutrition, the new findings show that bioactive compounds in blueberries called anthocyanins offer protection against hypertension. Compared with those who do not eat blueberries, those eating at least one serving a week reduce their risk of developing the condition by 10 per cent.
Anthocyanins belong to the bioactive family of compounds called flavonoids and are found in high amounts in blackcurrants, raspberries, aubergines, blood orange juice and blueberries. Other flavonoids are found in many fruits, vegetables, grains and herbs. The flavonoids present in tea, fruit juice, red wine and dark chocolate are already known to reduce the risk of cardiovascular disease.
Blueberries also probably cut colon cancer risk and improve brain function in the elderly. The USDA Procyanidin Database shows higher concentration for blueberries than strawberries. So the greater benefit from blueberries is not surprising.
Blueberries reduce the risk of hypertension with 10%. According to your figures the worldwide risk for that affliction is 25%. Does this new study mean that the risk of an enthousiastic consumer of blueberries is 15% or 22.5%? I havent read the study, but I suppose it is the latter. In many studies on the health benefits of food this is not clearly indicated, thereby inflating the expectations wrt 'healthy eating'. There are many many many studies indicating health benefits of isolated foodstuffs, but in the real world the effects of 'healthy eating' have been very disappointing. After a quarter of a century of healthy-food-journalism I have lost my faith and come to the conclusion that the human stomach is rather a garbage bin in which you can throw anything. Now that is clearly an exaggerration, but closer to the truth than the imaging of a human being as a fragile being whose fate is determined by minute quantities of micronutrients and the equilibrium of those. One sobering study was in Jama where 50.000 women were controlled to follow a healthy diet for 10 years after which no differences were found. She's not very active lately, alas, but Sandy Szwarc at http://junkfoodscience.blogspot.com/ has done a lot of good work in this field.
My amazing psychic powers tell me two things about this as yet unpublished study. It will be either:
(1) A proxy study in which a small group of subjects eats a lot of blueberries and then measurements are taken of physiological responses believed to predict hypertension later in life.
(2) A consumption based survey in which consumption of blueberries appears to correlate with low blood pressure but which is actually just a marker for an overall healthier lifestyle/socioeconomic class.
Either way, the correlation between blueberry and real world long-term lowering of blood pressure will be largely notional.
The science of optimal lifetime nutrition is an immature science at best. These studies come and go. They seem more like an art form than science.
Hope we won't see any overreactions like we did years ago when the fiber craze first hit. A man ate so much fiber cereal at one sitting that he had to be hospitalized, to have a 18-inch long plug of the stuff taken out of his intestines.
Aubergine = eggplant. But I suppose eggplants are far less sexy than blueberries.