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Vitamin C and Cardiovascular Disease: The Roots of Controversy

By Scarc
Vitamin C and Cardiovascular Disease: The Roots of Controversy

Caricature of Linus Pauling created by Eleanor Mill and published in the Philadelphia Inquirer, May 1992.

[Part 1 of 4]

“People are not dying from too much fatty food, they’re dying from too little vitamin C.”

-Linus Pauling, Vitamin C and Heart Disease, 1977

Health-conscious readers of a certain age have likely experienced a frustrating back and forth in food trends over the past several decades, and especially in the 1980s and 1990s. First eggs were said to be bad for you because they are high in cholesterol, then it was learned that they didn’t increase cholesterol in the blood. Likewise, butter was believed to be a health risk because of its high levels of saturated fats, however, butter (especially from grass fed animals, and especially as opposed to margarine) is now argued to be a valuable source of vitamins, minerals, and fatty acids. Chocolate and red meat, too, were decried for being too fatty or, in the case of chocolate, also too sugary. Yet today, both are viewed as useful and even valuable sources of nutrition, so long as they are consumed in moderation.

These swings in consensus swept across the United States beginning in the 1970s largely in response to rising concerns over cardiovascular disease, or CVD. CVD includes a range of maladies such as angina, or heart attack, and many occur in conjunction with atherosclerosis, or the build-up of fatty plaques on arterial walls.

Today, CVD remains the leading cause of death in the United States, claiming over 600,000 lives every year. As health professionals have sought to provide guidance on balanced eating, ideas have flip-flopped on the potential dangers of many foods because, over time, it has become increasingly clear that cutting these foods out of one’s diet altogether had little to no impact on rates of CVD.

Linus Pauling was arguing in support of this point of view long before the data had been gathered to confirm it. Pauling believed that the trend toward removing eggs, red meat, and whole milk from American diets was an ill-advised scheme that restricted valuable sources of protein and nutrients from individuals who often could not afford substitutes for these staple foods. In Pauling’s view, it should have been clear to physicians and other health professionals that these dietary sources of cholesterol could not significantly impact total cholesterol levels in the blood, because cholesterol is synthesized, to a great extent, within the body due to its importance in the maintenance of cell membranes.

The real problem behind heart disease, then, was not a high-cholesterol diet. The problem behind heart disease, Pauling argued, was a widespread failure to ingest a substance that could limit the body’s natural production of life-threatening cholesterol: Vitamin C.

As early as the late 1950s and early 1960s, researchers were uncovering evidence that high vitamin C intake reduced cholesterol in vitamin C-deficient guinea pigs, rats, and rabbits. Perhaps most notably, in the 1950s a Canadian group of researchers led by Dr. G.C. Willis found that above-average cholesterol intake did not result in plaque deposits in non-human subjects’ arteries so long as the diet was paired with a high-dose vitamin C regimen.

Intrigued, Linus Pauling began a search for other champions of this view, and in 1972 he wrote to Dr. Donald Harrison at the Stanford Medical School of Cardiology inquiring into additional research that was being conducted on the interplay between vitamin C and a reduction in the risk of cardiovascular disease. Harrison responded that, although the results were not yet published, he had found lower levels of cholesterol in the livers of guinea pigs that had been fed non-trivial doses of vitamin C.

By 1976 many had come to accept that vitamin C played some role in the regulation of cholesterol metabolism and thus in the progression, or lack thereof, of atherosclerosis and CVD. In addition to Harrison’s studies at Stanford, preliminary work conducted by researchers at Pennsylvania State University found that ascorbic acid and ascorbic acid sulfate (two forms of vitamin C) significantly reduced atherosclerosis caused by cholesterol plaques in rabbits.

However, at about this time, other research projects had suggested the opposite, and indicated that increased intake of vitamin C might in fact increase the risk of heart disease by inhibiting the absorption of copper in the intestinal tract. As a result of this inhibited absorption, the ratio of zinc to copper in the blood would stray from what is ideal and ultimately result in hypercholesterolemia: an imbalance in zinc and copper metabolism that is implicated in coronary heart disease.

These findings created a scenario in which the Pauling camp was squared off against many physicians over the confusing and opposing views that large doses of vitamin C both reduced and increased one’s risk of cardiovascular disease.

Throughout the 1970s, Pauling’s broad argument in favor of the fundamental importance of vitamin C to optimum human health was based on the idea that when primates lost the gene for vitamin C synthesis about forty million years ago, systematic physiological imbalances arose that continue to carry negative health consequences for humans today.

Pauling was quick to point out that all animals require vitamin C to live and that most synthesize it naturally. Yet humans – primates who do not synthesize their vitamin C naturally – typically obtain far less of it in their diet (when adjusted for body weight) than do other primates and non-synthesizing animals like guinea pigs. In addition, animals of this sort, when fed moderate to low levels of vitamin C, showed increased risk for development of arterial plaques of cholesterol.

What was less clear was whether or not this same effect was occurring in humans. Physicians opposed to Pauling’s view based their arguments on the idea that humans are physiologically different in important ways from the animals used to model the effects of vitamin C deficiency in the laboratory. Pauling scoffed at this notion and firmly believed that vitamin C deficiency in humans was the true cause of CVD. But even he could not fully explain exactly why vitamin C should be directly related to heart disease.

Over a decade later, in 1989, when a scientist named Matthias Rath came to the Linus Pauling Institute of Science and Medicine, Pauling would finally find what he believed to be the key to explaining how and why vitamin C was so important to the well-being of the human heart.

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