Personal trainers have long praised the health benefits of toning your muscles. Now, medical researchers are looking at a similar approach for toning of your blood vessels.
Think of it as getting really buff blood vessels.
So, what's blood-vessel tone got to do with your health? The better the tone of your blood vessels -- your total circulatory system -- the less your heart has to work to pump blood. When your heart pumps your blood smoothly, without resistance from your blood vessels, your risk of heart disease drops.
Although exercise is important for muscle tone, your eating and supplement habits may have greater sway when it comes to blood vessel tone. Eating fresh wholesome foods and taking antioxidants are the best ways to maintain tiptop blood-vessel tone.
How do you say endothelium?
The concept of improving your blood-vessel tone centers on the endothelium, a thin layer of cells that line the inside of your body's blood vessels. Researchers know that endothelial cells are major players in regulating blood flow, blood pressure, and even clotting. These cells secrete a variety of chemicals that signal blood vessels to dilate and constrict, which helps regulate blood flow, as well as to activate cells involved in blood coagulation.
Healthy blood vessels are elastic and flexible, accommodating changes in physical activity and stress levels. But in endothelial dysfunction (pronounced en-doe-thee-lee-uhl dis-funk-shin), blood vessels stiffen and reduce blood flow (that is, circulation) by 15 percent or more. Your heart has to work harder to make up the difference.
Although doctors understand that endothelial dysfunction is a major risk factor for coronary heart disease, it's not easily measured outside of university research environments. Instead, you have to infer the health of your endothelium based on your eating habits.
Fast foods make for flabby tone
One of the first significant studies linking diet and endothelial dysfunction was conducted almost 10 years ago at the University of Maryland School of Medicine in Baltimore. Gary D. Plotnick, M.D., and his colleagues compared the effects of a "high-fat" fast-food breakfast and antioxidant supplements on 20 healthy men and women. They used ultrasound to measure changes in blood-vessel tone and blood flow in the brachial artery, the same artery used to measure blood pressure in the upper arm.
Plotnick found that a typical McDonald's breakfast led to a significant and rapid decline in normal blood-vessel tone and blood flow. The changes lasted for two to four hours (until about when the average person might be hungry enough for another fast-food meal). But the good news was this: taking 800 IU of vitamin E and 1,000 mg of vitamin C prevented the dangerous changes in endothelial function.
The study clearly demonstrated the benefits of vitamins E and C, and Plotnick concluded that antioxidants help maintain normal endothelial function. But Plotnick erred in describing the fast-food breakfast as one high in saturated fat. While such a breakfast provides a hefty amount of saturated fat, it is also high in trans fats, refined carbohydrates, and sugars -- all of which can have a disastrous effect on blood-vessel tone.
Healthy diets help
Endothelial dysfunction -- again, think of it as poor blood-vessel tone -- is intertwined in inflammation and male sexual impotency. A variety of lifestyle factors increase the risk of endothelial dysfunction, including smoking tobacco, being overweight, and having either diabetes or prediabetes. Elevated blood levels of cholesterol, oxidized-LDL cholesterol, triglyceride, or homocysteine (yet another risk factor for heart disease), also increase the chances of having endothelial dysfunction. And so does feeling stressed.
In a study conducted at the State University of New York, Buffalo, researchers found that a similar McDonald's breakfast increased both inflammation and endothelial dysfunction in otherwise healthy subjects. Blood levels of a variety of inflammatory markers, such as C-reactive protein and "nuclear factor kappa beta (NFkB)," rose after the meal. NFkB promotes both inflammation and endothelial dysfunction in the body, according to Emmanouil N. Karatzis, M.D., of the Red Cross Hospital in Athens, Greece.
And yet dietary changes and supplements can help you maintain normal blood vessel tone. In a follow-up study, Plotnick and his colleagues reported that many of the components of the Mediterranean diet, including fish and antioxidant-rich vegetables, improved endothelial function.
A separate study, conducted at Harvard University, found that a variation of the Mediterranean diet (e.g., avoiding dairy and starchy potatoes) and a modified food-pyramid diet (allowing for multivitamins and moderate wine intake) led to substantial reductions in both inflammation and endothelial dysfunction.
Supplements for toning your blood vessels
Several supplements have been found beneficial in maintaining or restoring normal blood-vessel tone.
Vitamin E. Numerous studies have confirmed the benefits of vitamin E in improving endothelial function. This ability to maintain normal blood vessel tone may partly account for vitamin E's benefits in preventing cardiovascular diseases. In an extreme case, focusing on " acute" endothelial dysfunction in smokers, researchers found that 600 IU of vitamin E daily led to significant improvements in blood-vessel tone. A combination of 400 IU of vitamin E and 500 mg vitamin C daily enhanced endothelial function in children genetically predisposed to heart disease.
Vitamin C. By itself, vitamin C can also improve blood vessel tone. In a study of patients with heart disease, researchers found that 2,000 mg of vitamin C protected against endothelial dysfunction after a high-fat meal. Similarly, 1,000 mg of vitamin C blunted the endothelial dysfunction caused by elevated blood levels of homocysteine.
L-Arginine. This amino acid is the precursor to nitric oxide, one of the key regulators of endothelial function. Nitric oxide increases endothelial flexibility, and studies have found L-arginine supplements (6 to 15 grams daily) helpful in angina pain and congestive heart failure. Lower doses, such as 2 grams (2,000 mg) daily can help treat erectile dysfunction. L-arginine works the same way as prescription drugs for erectile dysfunction -- that is, by increasing nitric oxide levels and improve blood-vessel tone. Vitamin C may further improve the activity of L-arginine.
Garlic. Long revered for its health benefits, garlic is rich in antioxidants and increases nitric oxide production. In a study of 15 men with coronary heart disease, researchers found that 2.4 grams of aged garlic extracts reduced endothelial dysfunction by 44 percent.
Alpha-Lipoic Acid. This antioxidant has long been used in Europe to treat symptoms of diabetic nerve disease. In a recent study at the Emory University School of Medicine, Atlanta, researchers reported that 300 mg of alpha-lipoic acid improved enthothelial function by almost 50 percent, and the antioxidant also enhanced the benefits of a drug used to treat heart disease.
Flavonoids. Flavonoids are a family of more than 5,000 potent antioxidants found in fruits and vegetables. In a recent study, Mary Engler, Ph.D., R.N., found that blood-vessel tone improved after subjects consumed 1.6 ounces of flavonoid-rich dark chocolate daily for two weeks. The improvements appeared related specific to increases in epicatechin, one of the antioxidant flavonoids in dark chocolate.
In sum, the health of your total circulatory system has a major effect on your overall risk of developing heart disease. Research on endothelial function has clearly shown that eating deep-fried foods can have a disastrous effect on your blood vessel tone. In contrast, healthier foods and certain supplements can help you stay buff inside. And who wouldn't want to be buff?
Plotnick GD, Corretti MC, Vogel RA. Effect of antioxidant vitamins on the transient impairment of endothelium-dependent brachial artery vasoactivity follow a single high-fat meal. JAMA, 1997;278:1682-1686.
Whincup PH, Gilg JA, Donald AE, et al. Arterial distensibility in adolescents: the influence of adiposity, the metabolic syndrome, and class risk factors. Circulation, 2005;112:1789-1797.
Schalkwijk CG, Stehouwer, CD. Vascular complications in diabetes mellitus: the role of endothelial dysfunction. Clinical Science, 2005;109:143-159.
Ronco AM, Garrido A, Llanos MN, et al. Effect of homocysteine, folates, and cobalamin on endothelial cell- and copper-induced LDL oxidation. Lipids, 2005;40:259-264.
Rozanski A, Blumenthal JA, Kaplan J. Impact of psychological factors on the pathogenesis of cardiovascular disease and implications for therapy. Circulation, 1999;99:2192-2217.
Aljada A, Mohanty P, Ghanim H, et al. Increase in intranuclear nuclear factor kB and decrease in inhibitor kB mononuclear cells after a mixed meal: evidence for a proinflammatory effect. American Journal of Clinical Nutrition, 2004;79;682-690.
Karatzis E. The role of inflammatory agents in endothelial function and their contribution to atherosclerosis. Hellenic Journal of Cardiology, 2005;46:232-239.
Vogel RA, Corretti MC, Plotnick GD. The postprandial effect of components of the Mediterranean diet on endothelial function. Journal of the American College of Cardiology, 2000;36:1455-1560.
Fung TT, McCullough ML, Newby PK, et al. Diet-quality scores and plasma concentrations of markers of inflammation and endothelial dysfunction. American Journal of Clinical Nutrition, 2005;82:163-173.
Raghuveer G, Sinkey CA, Chenard C, et al. Effect of vitamin E on resistance vessel endothelial dysfunction induced by methionine. American Journal of Cardiology, 2001;88:285-290.
Sarabi M, Vessby B, Basu S, et al. Relationships between endothelium-dependent vasodilation, serum vitamin E and plasma isoprostane 8-iso-PGF2a levels in healthy subjects. Journal of Vascular Research, 1999;36:486-491.
Neunteufl T, Priglinger U, Heher S, et al. Effects of vitamin E on chronic and acute endothelial dysfunction in smokers. Journal of the American College of Cardiology, 2000;35:277-283.
Engler MM, Engler MB, Malloy MJ, et al. Antioxidant vitamins C and E improve endothelial function in children with hyperlipidemia. Endothelial assessment of risk from lipids in youth (EARLY) trial. Circulation, 2003;108;1059-1063.
Ling L, Zhao SP, Gao M, et al. Vitamin C preserves endothelial function in patients with coronary heart disease after a high-fat meal. Clinical Cardiology, 2002;25:219-224.
Chambers JC, McGregor A, Jean-Marie J, et al. Demonstration of rapid onset vascular endothelial dysfunction after hyperhomocysteinemia. An effect reversible with vitamin C therapy. Circulation, 1999;99:1156-1160.
Anon. Monograph: L-arginine. Alternative Medicine Review, 2005;10:139-147.
Tousoulis D, Xenakis C, Tentolouris C, et al. Effects of vitamin C on intracoronary L-arginine dependent coronary vasodilation in patients with stable angina. Heart, 2005;91:1319-1323.
Williams MJ, Sutherland WH, McCormick MP, et al. Aged garlic extract improves endothelial function in men with coronary artery disease. Phytotherapy Research, 2005;19:314-319.
Sola S, Mir MQ, Cheema FA, et al. Irbesartan and lipoic acid improve endothelial function and reduce markers of inflammation in the metabolic syndrome. Circulation, 2005;111:343-348.
Engler MB, Engler MM, Chen CY, et al. Flavonoid-rich dark chocolate improves endothelial function and increases plasma epicatechin concentrations in healthy adults. Journal of the American College of Nutrition, 2004;23:197-204.
About the author
Jack Challem, known as The Nutrition Reporter(tm), is a personal nutrition coach based in Tucson, Arizona. Jack is one of America's most trusted nutrition and health writers, and has written about research on nutrition, vitamins, minerals, and herbs for more than 30 years. He is the author of The Food-Mood Solution: The Nutrition and Lifestyle Plan to Feel Good Againem> (Wiley, 2007), Feed Your Genes Right (Wiley, 2005), The Inflammation Syndrome (Wiley, 2003) and the lead author of the best-selling Syndrome X: The Complete Nutritional Program to Prevent and Reverse Insulin Resistance (Wiley, 2000). His next book, Stop Prediabetes Now, will be published in the fall of 2007. He writes The Nutrition Reporter(tm) newsletter and contributes regularly to many magazines, including Alternative Medicine, Better Nutrition, Body & Soul, Experience Life, and Let's Live. Jack's scientific articles have appeared in Free Radical Biology & Medicine, Journal of Orthomolecular Medicine, Medical Hypotheses, and other journals. In addition, he is a columnist for Alternative & Complementary Therapies. Jack is a frequent speaker at nutritional medicine conferences and to consumer health groups. Email him via www.foodmoodsolution.com