Bloodletting: The Magic Bullet for the Diseases of Superabundance
Outdated notions about bloodletting make it the object of physicians’ scorn — and gross-out everyone else. It was how benighted medieval surgeons rebalanced bodily humors, and it hastened George Washington’s death. Overzealous bloodletting made Washington an early victim of the VIP syndrome, in which celebrity results in therapeutic misadventure.
In contrast, the modern history of bloodletting suggests it is the best remedy for certain diseases that become more common with a rising standard of living, the diseases of superabundance.1 These include metabolic syndrome, heart attacks, and coronary heart disease. Unfortunately, today’s refinement of bloodletting, therapeutic phlebotomy, is now a niche therapy.
The modern history of bloodletting begins with the Industrial Revolution. Industrialization created unprecedented wealth and the first disease of superabundance, called “plethora.”2 This was characterized by “increase of bulk” and “indulgence in the pleasures of the table” and was most common in people who “took little exercise.” 2 These characteristics describe metabolic syndrome as well.
In the first half of the 19th century, only the wealthy enjoyed superabundance. In the 21st century, though, too many indulge in superabundance, and the couch potato is a stereotype. The result is an epidemic of obesity, type 2 diabetes, and metabolic syndrome. Interestingly, physicians at the time of the Industrial Revolution noted that plethoric patients were the most likely to benefit from bloodletting.
Their observation gained experimental support in the 21st century from a controlled, randomized study of patients with metabolic syndrome, which found that two episodes of bloodletting of volumes similar to those removed during voluntary donations significantly decreased blood pressure and glucose concentrations.3
A high standard of living allows more people to eat a diet rich in saturated fats, the type found in red meat. These are solid at body temperature, whereas the unsaturated fats found in vegetables are liquid. The chemistry that makes saturated fats solid causes them to rigidify red blood cells, which are normally the most deformable biomaterial known. Rigid blood cells increase the thickness, or viscosity, of blood, which is reversed by bloodletting.
Sir William Osler, an exceptional observer and perhaps the greatest physician in history, was a strong supporter of bloodletting.3 In the 1921 edition of his classic textbook, The Principles and Practice of Medicine, he wrote:
The reproach . . . that a “bloody Moloch [a pagan god who demanded extravagant bloody sacrifice] presides in the chairs of medicine” cannot be brought against this generation of physicians. . . . We employ [bloodletting] much more than we did a few years ago, but more often late in the [pneumonia] than early. To bleed at the very onset in robust healthy individuals in whom the disease sets in with great intensity and high fever is good practice. Late in the course marked dilatation of the right heart is the common indication.3
Although pneumonia is not a disease of superabundance, it is associated with elevated blood viscosity because of the increased concentration of large proteins such as antibodies that the body produces to fight infection. This increases the pressure needed to pump blood. The resultant back pressure causes the heart to dilate. Decreasing blood viscosity by bloodletting improves blood flow to the lungs and the heart muscle. As a result, the function of the cardiovascular system improves. This boosts the delivery of oxygen and nutrients to the entire body, causing the therapeutic response in selected patients observed by Osler and other physicians since Hippocrates.
It may surprise many that a renowned 20th-century cardiologist, Chairman of Medicine at Tulane University School of Medicine for 28 years, AMA Scientific Achievement Award recipient, and long-time editor in chief of the American Heart Journal, George E. Burch, M.D., advocated and prescribed bloodletting in the second half of the 20th century.3 In 1979, he wrote:
It is well known that . . . a highly viscous fluid requires more work of the pump to circulate than does a less viscous liquid. Furthermore, the flow of highly viscous fluid is reduced. . . . Nevertheless, physicians fail to bleed patients with active coronary disease and myocardial ischemia [compromised blood flow to the heart muscle]. It has been shown that blood-letting . . . definitely improved the clinical state of these patients. . . . 3
After centuries of use, Burch was the first to articulate why bloodletting works: it lowers blood viscosity, thereby improving blood flow. At that time, medicine was too preoccupied with cholesterol to notice.
Despite bringing on the diseases of superabundance, industrialization must be considered to have been a boon to health. It allowed improved nutrition and made better sanitation and workplace safety necessary. In the United States, these contributed to an increase in life expectancy from the low to mid-fifties 100 years ago to the upper 70s to low 80s today.
Contrary to expectations, people fortunate enough to live to an advanced age 100 years ago didn’t die of heart attacks, the most common cause of death today.1 Osler didn’t mention them in the 1921 edition of his textbook but did discuss angina, the chest pain caused by a partial blockage of one of the coronary arteries that supply the heart. He noted it was rare but becoming more common, with one case a year expected in large metropolitan hospitals. It was, he wrote, a disease of the “better” classes.
Based on mortality data, the epidemic of heart disease in the United States can be pinpointed to one event: the introduction of trans fats to the diet in 1911.1 In 1912, a heart attack was diagnosed in a living patient for the first time. Beginning in 1913, the number of deaths due to heart disease rose continuously until the mid-1960s. This increase was interrupted only by rationing necessitated by the two world wars, reinforcing the observation that heart disease is a disease of superabundance.
The epidemic of heart disease followed a similar pattern in the United Kingdom. Trans fats were introduced there in 1909. In 1913, angina pectoris was addressed for the first time in the third edition of Diseases of the Heart, written by the father of British cardiology, Sir James Mackenzie. The continuous increase of heart attacks in the U.K. is estimated to have begun between 1922 and 1924. The delay compared to the U.S. reflects the greater deprivation caused by WWI.
Trans fats are produced by chemically modifying liquid vegetable oil to make a solid, inexpensive alternative to animal lard. Like fats from red meat, consumption of trans fats stiffens red cells and elevates blood viscosity. Trans fats are estimated to have caused 100,000 excess deaths annually in the United States at one time. As a cause of self-inflicted harm, trans fats are exceeded only by warfare, air pollution, and cigarette smoking.
Like the other diseases of superabundance, the best prevention for a heart attack is bloodletting or blood donation.3 In a Finnish study published in 1998, men who donated blood had an 88% reduction in the risk of heart attack. Of 2529 men who did not donate blood, 316 suffered a heart attack, compared to only 1 of 153 donors. This study must be replicated.
Bloodletting fell into disfavor before antibiotics were used to treat pneumonia and long before the diseases of superabundance became common. Why this happened is still debated.2 In an extended public debate about the efficacy of bloodletting in the mid-19th century, William Putney Alison, a senior Edinburgh physician, was incredulous that every physician since Hippocrates could have been wrong about the efficacy of bloodletting; his opponent, John Hughes Bennett, a young pathologist, insisted that bloodletting was never effective and “ultimately only a big mistake.”2
Bloodletting doesn’t change the appearance of pneumonia through the microscope. At most, improved blood flow without antibiotics provides symptomatic relief and could reduce the mortality of pneumonia slightly. The instruments used to measure red blood cell rigidity and blood viscosity are still primarily research tools. Without evidence from those, the benefit of bloodletting and improved blood flow may be too subtle for any but the keenest observers to appreciate. In retrospect, it is clear that a callow youth, unaware of the limitations of the microscope, won a too complete victory over an experienced clinician whose observations were accurate but who lacked data.
When suboptimal nutrition and anemia were common, physicians needed to increase blood viscosity. In the age of superabundance, the mission of physicians should be to decrease blood viscosity. The father of chemotherapy, Paul Ehrlich, envisioned that the best therapeutic was like a magic bullet, one that hit the target without causing collateral damage. Bloodletting is a magic bullet for the diseases of superabundance.
1. Sloop GD. How eating too well hurts you, or managing the diseases of superabundance. Medium. July 1, 2019. Accessed September 8, 2021. https://bigdaddypathologist.medium.com/managing-the-diseases-of-superabundance-2d998e0537e4.
2. Carter KC. Change of type as an explanation for the decline of therapeutic bloodletting. Stud Hist Philos Biol Biomed Sci. 2010;41: 1–11.
3. Sloop GD, ed. Blood Viscosity: Its Role in Cardiovascular Pathophysiology and Hematology. Nova Biomedical; 2017.
