A new study, published in the Journal of Nutrition (November 2007, Volume 137, Pages 2405-2411) titled “Quercetin Reduces Blood Pressure in Hypertensive Subjects”, is said to be the first to report the blood pressure-lowering activity of this flavonol. The study found that a supplement of quercetin (naturally occurring component of onion) led to significant reductions in the blood pressure of 22 people with high blood pressure.
Red Onions contain quercetin a flavonol found to lower high blood pressure
The randomised, double blind, placebo-controlled, crossover study, considered to be the gold-standard for experimental interventions, adds to an ever-growing body of reported health benefits for quercetin. The flavonol was previously linked to reduced risk of certain cancers. Building on science from animal studies reporting a potential hypotensive (blood pressure lowering) role for the flavonol, researchers from the University of Utah recruited 19 men and women with pre-hypertension (average BP 137/86 mmHg) and 22 hypertensives (average BP 148/96 mmHg). The subjects were randomly assigned to receive a daily supplement of quercetin or a placebo for 28 days. Lead author Randi Edwards and co-workers report that the hypertensives receiving the quercetin supplement experienced reductions in systolic and diastolic BP of 7 and 5 mmHg, respectively, compared to placebo. No BP changes were observed in the pre-hypertensives as a result of either intervention.
Specific whole foods of the allium family such as onions and garlic have a long history of being associated with cardiovascular benefits. This new evidence further clarifies one way onions support heart health by working to lower elevated blood pressure in people with high blood pressure.
Publishing in the journal Nutrition Research scientists showed that a combination of garlic and vitamin-C are effective in helping those with marginally elevated blood pressure to get it down. They reported that while garlic alone provided some benefit, vitamin-C alone did not. But when the two are combined a significant reduction in blood pressure was noted. They pointed out that the blood pressure of their subject decreased when garlic and vitamin-C were delivered together and increased when the supplements were taken away. (Nutrition Research; Volume 27, Issue 2, pages 119-123, March 2007)
Foods rich in highly colored pigmens of red, orange, and yellow are rich sources of carotenoids
Lutein is a yellow-to-orange pigment or phytochemical found mostly in plants and works as an antioxidant in your body to reduce the damage done by free radicals. Lutein is a carotenoid and is related to vitamin A. Other carotenoids include beta carotene, alpha carotene and zeaxanthin.
The first research to show a positive connection between the carotenoid lutein to heart health came in a 2001 issue of Circulation (vol. 103, pp. 2922- 2927). Now researchers from Sweden have found yet another strong link. Publishing in the February 2006 issue of Nutrition, Metabolism and Cardiovascular Disease (doi: 10.1016/numecd.2006.02.2006) the researchers pointed out that people suffering from coronary artery disease are consistently found to have low levels of the carotenoids lutein, zeaxanthin and beta cryptoxanthin. Conversely, they found that the healthy persons in the control group had significantly higher levels of these carotenoids in their blood. They think it’s connected to immune function because of higher levels of natural killer cells (NK cells) in the people with higher levels of these carotenoids. “This finding suggests a specific link between certain carotenoids, oxidative stress, and immune perturbation imbalance in Cardiovascular Disease,” said lead researcher Caroline Lidebjer from the University Hospital at Linkoping, Sweden.
Though the research on whole foods – including whole grains, fruits, vegetables, and fish – may and their relevance to cardiovascular health currently overshadow studies on minerals, new research on minerals is happening. Here are some examples:
Magnesium: Is it an anti-inflammatory mineral?
Research published in the journal Nutrition Research (vol. 26, pp 193-196) indicates that it is. Using a blood chemistry marker associated with heart disease and inflammation known as C-reactive protein (CRP) researchers showed that magnesium has anti-inflammatory actions in the body. Elevated C-reactive protein CRP is a consistent indicator of chronic inflammation because it is one of the bodies “signalling molecules.” The higher and longer the inflammation exists, the higher the CRP values. “Previous research has indicated that dietary magnesium may be a key component in the association between diet and inflammation” proffers lead study author and Medical University of South Carolina professor Dana King. “The key finding in this study is that magnesium intake from supplements has an impact on the likelihood of having elevated C-reactive protein.” People with dietary magnesium intake below the required daily allowance (RDA) were found to have a 40% higher risk of elevated CRP.
Zinc is an anti-inflammatory mineral too!
Because zinc has long been known as an important building block of natural antioxidant enzymes made in the body, such as glutathione, peroxidase, and super oxide dismutase, it is thought of as a “protector mineral.” Two recent studies further support zinc’s critical importance. The September 2005 issue of the Journal of Nutrition (vol. 135, pp 2114-2118) reported that zinc deficiency was associated with increased risk of cardiovascular disease through inflammation. New research published online in the March 2006 issue of the journal Free Radical Biology in Medicine (doi:10.1016/j.freeradbiomed.2006.03.017) further supports the oxidation/inflammation risk of deficiency.
Depleted soils and industrialized farming have combined to reduce the mineral content of many foods previously rich in essential minerals. Minerals are a key link in the Chain of Life and assuring deficiencies don’t exist is a smart health move for all.
A large scale review of studies of calcium intake and risk of hypertension and pre-eclampsia during pregnancy suggests this is an important discussion for women to have with their obstetrician. The review, published in the Cochrane Database of Systematic Reviews (2006, issue 3), quotes lead author Dr. G. Justus Hofmeyr, “The findings of the review are that calcium supplementation reduces the risk of hypertension for pregnant women who have inadequate dietary calcium.” In support of these findings, independent pre-eclampsia expert Dr. John Repke, Chairman of Obstetrics and Gynaecology at Penn State University College of Medicine commented “Calcium supplementation may be of some benefit in reducing morbidity (death) associated with pre-eclampsia and it does no harm.”