Lowering Your Cancer Risk by Donating Blood

Back in the early 1980s, a pathologist in Florida suggested that the reason premenopausal women are protected from heart disease is that they have lower stores of iron in their body. Since oxidized cholesterol is “important in atherosclerosis, and oxidation is catalyzed by iron,” might the lower iron stores of menstruating women reduce their risk of coronary heart disease? “The novel insight suggesting that the longevity enjoyed by women over men might relate to the monthly loss…of blood is remarkable,” but is it true? I discuss this in my video Donating Blood to Prevent Heart Disease?.

The consumption of heme iron—the iron found in blood and muscle—is associated with increased risk of heart disease. Indeed, “an increase in heme iron intake of 1 mg/day appeared to be significantly associated with a 27% increase in risk of CHD,” coronary heart disease. But, heme iron is found mainly in meat, so “it is possible that some constituents other than heme iron in meat such as saturated fat and cholesterol are responsible” for the apparent link between heme iron and heart disease. If only we could find a way to get men to menstruate, then we could put the theory to the test. What about blood donations? Why just lose a little blood every month when you can donate a whole unit at a time?

A study in Nebraska suggested that blood donors were at “reduced risk of cardiovascular events,” but another study in Boston failed to show any connection. To definitively resolve the question, we would really have to put it to the test: Take people at high risk for heart disease, randomly bleed half of them, and then follow them over time and see who gets more heart attacks. Maybe it could turn “bloodletting” from the past into “bleeding-edge technology.” In fact, that was actually what was suggested in the original paper as a way to test this idea: “The depletion of iron stores by regular phlebotomy could be the experimental system for testing this hypothesis…”

It took 20 years, but researchers finally did it. Why did it take so long? There isn’t much money in bloodletting these days. I suppose the leech lobby just isn’t as powerful as it used to be.

What did the researchers find? It didn’t work. The blood donors ended up having the same number of heart attacks as the non-donor group. Something extraordinary did happen, however: The cancer rates dropped. There was a 37 percent reduction in overall cancer incidence, and those who developed cancer had a significantly reduced risk of death. An editorial in the Journal of the National Cancer Institute responded with near disbelief, saying the “results almost seem to be too good to be true.” “Strikingly,” they started to see cancer reduction benefits within six months, after giving blood just once. As the study progressed, the cancer death rates started to diverge within just six months, as you can see at 2:46 in my video, but this is consistent with the spike in cancer rates we see within only six months of getting a blood transfusion. Is it possible that influx of iron accelerated the growth of hidden tumors?


I continue this wild story in my video Donating Blood to Prevent Cancer?.

What if you feel faint when you give blood? Don’t worry. I’ve got you covered. Check out How to Prevent Fainting.

What might iron have to do with disease? See The Safety of Heme vs. Non-Heme Iron and Risk Associated with Iron Supplements.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Proof that Lifelong Cholesterol Reduction Prevents Heart Disease

“It is well accepted that coronary atherosclerosis is a chronic progressive disease that begins early in life and slowly progresses over several decades” before symptoms arise. However, the average age in cholesterol-lowering drug trials is 63; therefore, people have already been exposed to a lifetime of circulating LDL cholesterol. It’s no wonder pharmaceutical therapies typically reduce cardiovascular disease risk by only 20 to 30 percent.

We know LDL, the so-called bad cholesterol, plays “a central role” in the “initiation, development, and progression” of our number-one killer. In fact, more than 100 prospective studies involving more than a million people have demonstrated that those with higher LDL levels are at higher risk.

“It seems reasonable to assume, therefore, that if lowering LCL-C [cholesterol] levels beginning later in life can slow the progression of advanced atherosclerotic plaques…then keeping LDL-C levels low, beginning much earlier in life” might prevent our arteries from getting clogged in the first place. A reasonable assumption, certainly—but let’s not just assume.

“It would be…unethical to set up a controlled clinical trial in which young adults with elevated serum cholesterol levels were treated or not treated over their lifetime”—just as we couldn’t ethically set up a study in which half the young adults are made to start smoking to see if smoking really does cause lung cancer. That’s where observational studies come in. We can follow people who already smoke and compare their disease rates to those who don’t.

It was aroud 40 years ago when the president of the American Heart Association tried to argue we should all stop smoking even though there were no randomized controlled trials. You can see a copy of the “Presidential Address” entitled “The Case for Prevention of Coronary Heart Disease” to the AHA’s 47th Scientific Sessions at 1:34 in my video. Those who smoke have a higher risk of heart attack, and the more we smoke the higher the risk. After we stop smoking, our risk drops. The same can be said for high cholesterol.

Young men 18 through 39 years of age were followed for up to 34 years, and their cholesterol levels, even when they were young, predicted long-term risk of heart disease and death. Men in their 20s and 30s who have a total cholesterol just under 200 have a “substantially longer estimated life expectancy”—around 4 to 9 years longer—than those with levels over 240.

“Evidence from observational studies, however, [is] vulnerable to confounding” factors. Eating a diet that is plant-based enough to lower cholesterol below average, for example, may add years to our lives regardless of what our cholesterol actually is. Ideally, we’d have a long-term, randomized, controlled trial.

Nature may have actually set one up for us. Each of us, at conception, gets a random assortment of genes from our mother and our father, and some of those genes may affect our cholesterol levels. Just like there are rare genetic mutations that result in unusually high cholesterol levels, there are rare genetic mutations that lead to unusually low cholesterol levels, “provid[ing] an ideal system in which to assess the consequences of low LDL cholesterol levels independently of other factors that may modify disease progression,” such as confounding diet and lifestyle factors.

Starting at 3:14 in my video, you can see what I mean. About 1 in 40 African Americans have a mutation that drops their LDL cholesterol from around 130 down toward more optimal levels. Now, this group didn’t eat healthy to get achieve that drop. It’s just in their genes. More than half had high blood pressure and there were a lot of smokers and diabetics in the group, yet those with genetically low LDL levels still had a significant reduction in the incidence of coronary heart disease even in the presence of all those other risk factors. How significant? How much less heart disease? A remarkable 88 percent of heart disease was simply gone.

The astounding finding was that the risk of heart disease in these individuals was reduced by more than 80 percent, whereas the same 20- to 40-point decrease in LDL from drugs only reduces risk around 30 percent. Makes sense, though, because the folks with the mutation had low levels their entire life. They didn’t simply start taking a pill when they were 60.

“The magnitude of the effect of long-term exposure to lower LDL-C [cholesterol] concentrations observed in each of these studies represents a threefold greater reduction in the risk of CHD,” or coronary heart disease, compared to drug treatment started later in life. (As an aside, for all of my fellow research nerds, check out that p value shown in my video at the 4:30 mark. You’d have to do arourd a quintillion studies to get that kind of result by chance!)

“Therefore, a primary prevention strategy that promotes keeping LDL [cholesterol] levels as low as possible, beginning as early in life as possible, and sustaining those low levels of LDL [cholesterol] throughout the whole of one’s lifetime has the potential to dramatically reduce the risk of CHD,” coronary heart disease.


If you don’t know your cholesterol level, you should get it checked—maybe even starting in childhood. See my video Should All Children Have Their Cholesterol Checked? to learn more.

What if you do get tested and your doctor tells you not to worry because your cholesterol’s “normal”? Having a “normal” cholesterol level in the society where it’s normal to drop dead of a heart attack (the number-one killer of men and women) is not really such a good thing. See my video When Low-Risk Means High-Risk.

Check out Optimal Cholesterol Level and What’s the Optimal Cholesterol Level? to find out where you should be.

What if your doctor tells you your LDL is large and fluffy? See my video Does Cholesterol Size Matter?.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

All Children Should Have Their Cholesterol Checked Between Ages 9 and 11

Coronary artery disease does not magically appear. The disease begins “during early childhood and progress[es] unrecognized for several decades to its often final and unexpected endpoint of chest pain, disability, or premature death.”

As I discuss in my video Should All Children Have Their Cholesterol Checked?, “we need to remind ourselves that atherosclerosis begins in childhood as fatty streaks” in the arteries, which “are the precursors of the advanced lesions that ultimately” kill us. By the time we’re in our 20s, 20 percent of the inner surface of the artery coming off the heart is covered in fatty streaks, as you can see at 0:58 in my video. Fifty years ago, pathologists began raising the question of whether heart disease is best handled by cardiologists or by pediatricians.

“By their 30s, many young adults already have advanced coronary atherosclerosis,” so, in reality, intervention during our 30s and beyond “is actually secondary prevention, because advanced atherosclerosis is likely already present.” Indeed, intervention is just trying to mediate the ravages of the disease rather than prevent the disease itself.

What’s more, we are exporting the problem around the world. A study of young, thin, apparently healthy individuals found 97 percent of their collected arteries had atherosclerosis, which you can see at 4:52 in my video. So, even in developing countries like Brazil, where they’ve acquired our eating habits, we’re seeing an epidemic of heart disease and sudden death.

“Moreover, the risk factors that correlate with the extent of such early lesions are the same risk factors that correlate with myocardial infarction [or, heart attacks] later in life.” In other words, it’s the same disease but in the early stages. So, pathologists, the ones doing the autopsies on all these young people and seeing all this coronary artery disease, “began urging many years ago that preventive measures should be instituted earlier in life.”

We’ve known that fatty streaks exist in young children for more than a century, but it wasn’t until 1994 that a task force convened by the government came up with a “radical” idea: “The strategic key, and the greatest opportunity in preventing [cardiovascular disease] CVD, is to prevent the development of CVD risk in the first place.”

In my video Heart Disease Starts in Childhood, I noted that fatty streaks, the first stage of atherosclerosis, were found in the arteries of nearly 100 percent of kids by age ten who were raised on the standard American diet. In recognition of this fact, the latest Academy of Pediatrics’ recommendation is for all kids to get their cholesterol tested starting between the ages of 9 and 11.

Of course, this has drug companies salivating at the thought of slipping statins into Happy Meals, but “long-term drug intervention is costly and may be associated with adverse effects.” So, the conversation is about lifestyle modification.

In my video How Many Meet the Simple Seven?, I revealed the breathtaking statistic that only about 1 in 2,000 U.S. adults met the seven American Heart Association criteria for a heart-healthy lifestyle. What about American teenagers? Of the 4,673 adolescents aged 12 to 19 who were studied, zero made the cut. Not one teen “exhibited ideal levels of all 7 cardiovascular health behaviors and health factors.”

Most teen boys and girls don’t smoke, and most aren’t overweight. What was the main sticking point? Almost no one ate a healthy diet. Indeed, less than 1 percent of young men and women met a minimum of healthy diet criteria.

This sorry state of affairs is what’s behind a “controversial valuation that the current generation of US children and adolescents may be one of the first generations to be less healthy and have shorter life expectancy than their parents.”


If you think atherosclerosis by age ten is bad, check out my video Heart Disease May Start in the Womb.

Adverse effects with cholesterol-lowering drugs? See Statin Muscle Toxicity. I don’t think most people realize—doctors and patients alike—realize how relatively ineffective these drugs are. Watch, for example, The Actual Benefit of Diet vs. Drugs.

Cholesterol can do more than just build up and block off our arteries. In fact, Cholesterol Crystals May Tear Through Our Artery Lining.

What’s the Optimal Cholesterol Level? Does Cholesterol Size Matter? Watch the videos to find out.

Let’s take a step back, though. What about all the “cholesterol skeptics”? Check out How Do We Know That Cholesterol Causes Heart Disease?.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations: