Doctor’s Tip column: Diet and blood pressure
When scientists study large populations of people and look at what diseases they get and what they die from, it becomes apparent that ideal blood pressure is 110/70 or below. As blood pressure rises above that level — especially 140/90 or above — the incidence rises for heart attacks; strokes; damage to blood vessels in the eyes, kidneys, and brain; aortic and brain aneurysms; dementia; and heart failure.
In countries on a Western diet — high in animal products, refined food, salt, sugar and fat/oil — blood pressure tends to rise as people age, and the majority of people eventually develop hypertension (high blood pressure).
Although this scenario is common, it is not normal. In populations such as rural Africa and rural China, where people eat unprocessed, plant-based food low in salt (sodium), blood pressures remain in the 110/70 range, even in people in their 90s.
In the 1940s, before effective blood pressure medications had been developed, people with severe hypertension — such as FDR — usually died. Walter Kempner, M.D., at Duke University, put these severe hypertensives on a strict fruit and white rice diet with no added salt. Blood pressures in the 240/150 range came down to the 105/80 range.
Obviously, this diet was monotonous and lacked many important nutrients, but Dr. Kempner proved that hypertension is caused by what people eat, and can be treated with dietary changes.
In spite of what the Salt Institute would like us to believe, salt clearly causes hypertension, although some people respond to salt more than others. Salt causes water retention, and your body responds to this by increasing your blood pressure, in order to eliminate the excess water and salt. Your blood pressure rises soon after eating a salty meal, and if you eat too much salt on a regular basis you will likely end up with sustained hypertension.
During most of the millions of years of human evolution, humans were eating just a few hundred milligrams of salt, through their plant-based diet. We now eat about 10 times that amount. The maximum safe amount of salt for adults is 1,500 mg.
Cheese and processed foods have particularly high salt content. The primary source of salt in kids and teenagers is pizza. In young adults the main source is chicken — the poultry industry commonly injects chicken carcasses with salt water to artificially inflate their weight. In older adults, the main source of salt is bread.
People who eat animal products are more apt to be overweight, which is a major cause of hypertension. Furthermore, they are more apt to develop stiffening and hardening of the arteries (atherosclerosis), which cause their blood pressure to rise as they age.
Vegetables, fruit and whole grains on the other hand, cause the endothelium to produce nitric oxide, which makes arteries dilate. Nitric oxide also makes arteries healthier, and more resistant to atherosclerosis. Organizations such as the American Heart Association, the American College of Cardiology and the Center of Disease Control recommend that patients with hypertension first try weight reduction, limiting sodium and alcohol, exercising and eating a healthier diet.
However, what they recommend as a healthy diet is the DASH (Dietary Approaches to Stop Hypertension) diet. This diet emphasizes fruits, vegetables, and low-fat diet — some meat is also allowed, and it does lower blood pressure somewhat.
Dr. Sachs, of Harvard, was chairman of the committee that developed the DASH diet. His investigation found that the people in industrialized countries with the lowest blood pressures were vegetarians — and vegans even more so. His committee recommended the DASH diet because their goal was to create eating patterns “that would have the blood pressure lowering benefits of a vegetarian diet yet contain enough animal products to make them palatable to nonvegetarians.”
In his book “How Not to Die,” Dr. Michael Greger notes that “instead of simply telling you what the science shows and then letting you make up your own mind, experts patronize the population by advocating what they think is practical rather than ideal.”
Unfortunately, not everyone with high blood pressure is willing to change their lifestyle enough to impact it significantly. Next week’s column will discuss common blood pressure medications.
Retired physician Greg Feinsinger, MD, is author of the new book “Enjoy Optimal Health, 98 Health Tips From a Family Doctor,” available on Amazon and in local bookstores. Profits go towards an endowment to the University of Colorado School of Medicine to add prevention and nutrition to the curriculum. For questions about his column, email email@example.com.
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