Narrowed, aging blood vessels, which put most older American adults at risk for heart disease and strokes, are not inevitable. This fact was underscored by a newly published study of a population in the Bolivian Amazon.
Among these indigenous South Americans, known as the Tsimane (pronounced chee-MAH-nay), coronary atherosclerosis was found to be one-fifth as common than in the United States. CT scans of the hearts of 705 Tsimane adults ages 40 to 94 revealed that nearly 9 in 10 had clean coronary arteries and faced no risk of heart disease. The research team estimated that an 80-year-old in the Tsimane group has the same vascular age as an American in his mid-50s.
I'll return to the likely reasons and the lifesaving lessons we can all learn from them even now after a discussion of a half-century of improvements in the heart health of Americans.
In the early 1960s, when I began writing about science and health, American hearts were in dismal condition. Heart disease, an uncommon cause of death at the turn of the 20th century, had become the most common cause of death by midcentury.
Coronary mortality peaked in 1968, when it was not unusual for Americans to die of a heart attack in their 50s or 60s. At the time, about 40 percent of adults smoked, doctors deemed a cholesterol level of 240 milligrams per deciliter to be “normal,” and nearly half of young adults had blood pressure readings now considered high.
Had the coronary death rate continued its meteoric rise, today more than 1.7 million Americans would succumb to heart disease each year. Instead, there’s been a significant decline, to some 425,000 deaths a year, with a commensurate increase in longevity of 8.7 years between 1970 and 2010. More than 70 percent of the rise in life expectancy is attributable to fewer deaths from cardiovascular disease, primarily heart attacks and strokes.
The countless millions who have escaped a premature cardiovascular death can thank in part a half-century of public health measures and other preventive medicine initiatives that are now threatened by proposed cuts in the nation’s budget.
The fall in cigarette smoking alone had a major impact, having declined to about 15 percent of adults. (Alas, teenagers, whose smoking rates were once well below those of adults, have all but caught up.) Smoking by itself increases the risk of heart disease; it raises blood pressure, diminishes exercise tolerance, decreases protective HDL cholesterol, and increases the blood’s tendency to clot.
But when smoking is combined with other coronary risk factors, like high blood pressure, high cholesterol, obesity or Type 2 diabetes, the risks of a heart attack, stroke and an early coronary death are greatly increased.
A decline in average blood levels of cholesterol also played an important role in the drop in coronary deaths. Today only about 12 percent of American adults have high total cholesterol levels – 240 milligrams or greater, although nearly a third still have elevated levels – 130 milligrams or more – of artery-damaging LDL cholesterol.
People with high total cholesterol face nearly twice the risk for heart disease as those with ideal levels (200 milligrams or less), and a high level of LDL cholesterol – above 100 milligrams – is even more problematic. Yet even now, fewer than half of adults with elevated LDL levels are being treated to reduce it.
Recognizing and treating high blood pressure, based on the findings of a slew of studies of promising medications, has helped to save the hearts and lives of countless Americans who might otherwise have succumbed to coronary disease since its peak incidence.
Nonetheless, today one adult in three has high blood pressure, and of those only half have it under control. Another third of adults have blood pressure that is higher than normal, though not yet in the high blood pressure range. Thus, poor treatment remains a serious contributor to cardiovascular disease and deaths.
Too often, the American approach to heart disease amounts to shutting the barn door after the horse has escaped. Once in trouble with life-threatening arterial damage, patients are usually treated with stents in hopes of keeping the vessels from closing down, at a cost of $30,000 to $50,000 for each procedure.
But while having a stent in place can indeed be helpful for those in the throes of a heart attack, at least eight randomized clinical trials found that for people with stable coronary artery disease, they offer no benefit over standard noninvasive medical treatment – diet, exercise and perhaps treatment with an inexpensive statin. Yet, more than half of stable coronary patients, who may have symptoms like chest pain during vigorous exercise, are treated with stents before they’ve tried conservative therapy.
So what can we learn from the Tsimane? Are medications, treatment with stents and other costly procedures our only hope for cutting coronary mortality further? Yes, if millions of Americans continue to spurn changes in their living habits that have been shown over and over again to be protective.
The Tsimane have a forager-horticulturist lifestyle. Tsimane men are physically active for an average of six to seven hours a day – accumulating about 17,000 steps a day – and Tsimane women are active for four to six hours a day, walking about 15,000 steps a day. Smoking is rare in this population.
The Tsimane diet derives 72 percent of its calories from carbohydrates, though not the overly refined starches and sugars consumed by most Americans. The Tsimane eat unprocessed complex carbs high in fiber, like brown rice, plantain, manioc, corn, nuts and fruits.
But the Tsimane are not vegetarians. Protein accounts for 14 percent of their calories and comes primarily from animal meats that, unlike American meats, are very low in artery-clogging saturated fat.
This does not mean we must return to hunting and gathering or subsistence farming to protect our hearts. But we’d do well to adapt the Tsimane example and modify our modern high-fat, highly processed, low-fiber and high-sugar diet and our extremely sedentary lifestyle.
Most Americans today are nearly or completely inactive. Barely 20 percent of adults get the recommended minimum of 30 minutes a day of physical activity, and fewer than half of adults get enough activity to achieve any meaningful health benefits.
In fact, a new study by researchers at Columbia University Medical Center found that only 16 percent of heart attack survivors get enough activity after hospital discharge: In the first two weeks, at least 30 minutes a day of moderate aerobic exercise like brisk walking at least five days a week is recommended.