Dialing Down the Grim Reaper Gene

Only about 1 in 10,000 people live to be a 100 years old. What’s their secret? I discuss this in my video Animal Protein Compared to Cigarette Smoking.

In 1993, a major breakthrough in longevity research was published about a single genetic mutation that doubled the lifespan of a tiny roundworm. Instead of all worms being dead by 30 days, the mutants lived 60 days or longer. This lifespan extension was “the largest yet reported in any organism.” This methuselah worm, a “medical marvel,” is “the equivalent of a healthy 200-year-old human.” All because of a single mutation? That shouldn’t happen. Presumably, aging is caused by multiple processes, affected by many genes. How could knocking out a single gene double lifespan?

What is this aging gene—a gene that so speeds up aging that if it’s knocked out, the animals live twice as long? It’s been called the Grim Reaper gene and is the worm equivalent of the human insulin-like growth factor 1 (IGF-1) receptor. Mutations of that same receptor in humans may help explain why some people live to be a hundred and other people don’t.

So, is it just the luck of the draw whether we got good genes or bad ones? No, we can turn on and off the expression of these genes, depending on what we eat. Years ago I profiled a remarkable series of experiments about IGF-1, a cancer-promoting growth hormone released in excess amounts by our liver when we eat animal protein. Men and women who don’t eat meat, egg white, or dairy proteins have significantly lower levels of IGF-1 circulating within their bodies, and switching people to a plant-based diet can significantly lower IGF-1 levels within just 11 days, markedly improving the ability of women’s bloodstreams to suppress breast cancer cell growth and then kill off breast cancer cells.

Similarly, the blood serum of men on a plant-based diet suppresses prostate cancer cell growth about eight times better than before they changed their diet. However, this dramatic improvement in cancer defenses is abolished if just the amount of IGF-1 banished from their systems as a result of eating and living healthier is added back. This is one way to explain the low rates of cancer among plant-based populations: The drop in animal protein intake leads to a drop in IGF-1, which in turn leads to a drop in cancer growth. The effect is so powerful that Dr. Dean Ornish and colleagues appeared to be able to reverse the progression of early-stage prostate cancer without chemotherapy, surgery, or radiation—just a plant-based diet and lifestyle program.

When we’re kids, we need growth hormones to grow. There’s a rare genetic defect that causes severe IGF-1 deficiency, leading to a type of dwarfism. It also apparently makes you effectively cancer-proof. A study reported not a single death from cancer in about 100 individuals with IGF-1 deficiency. What about 200 individuals? None developed cancer. Most malignant tumors are covered in IGF-1 receptors, but if there’s no IGF-1 around, they may not be able to grow and spread.

This may help explain why lives appear to be cut short by eating low-carb diets. It’s not just any low-carb diet, though. Specifically, low-carb diets based on animal sources appear to be the problem, whereas vegetable-based low-carb diets were associated with a lower risk of death. But low-carb diets are high in animal fat as well as animal protein, so how do we know the saturated animal fat wasn’t killing off people and it had nothing to do with the protein? What we need is a study that follows a few thousand people and their protein intakes for 20 years or so, and sees who lives longest, who gets cancer, and who doesn’t. But, there had never been a study like that…until now.

Six thousand men and women over age 50 from across the United States were followed for 18 years, and those under age 65 with high protein intakes had a 75 percent increase in overall mortality and a fourfold increase in the risk of dying from cancer. Does it matter what type of protein? Yes. “These associations were either abolished or attenuated if the proteins were plant derived,” which makes sense given the higher IGF-1 levels in those eating excess protein.

The sponsoring university sent out a press release with a memorable opening line: “That chicken wing you’re eating could be as deadly as a cigarette.” It explained that “eating a diet rich in animal proteins during middle age makes you four times more likely to die of cancer than someone with a low-protein diet—a mortality risk factor comparable to smoking.” And when they say “low-protein diet,” what they actually mean is getting the recommended amount of protein.

“Almost everyone is going to have a cancer cell or pre-cancer cell in them at some point. The question is: Does it progress?” said one of the lead researchers. That may depend on what we eat.

“[T]he question is not whether a certain diet allows you to do well for three days,” a researcher noted, “but can it help you survive to be 100?” Excessive protein consumption isn’t only “linked to a dramatic rise in cancer mortality, but middle-aged people who eat lots of proteins from animal sources…are also more susceptible to early death in general.” Crucially, the same didn’t apply to plant proteins like beans, and it wasn’t the fat; the animal protein appeared to be the culprit.

What was the response to the revelation that diets high in meat, eggs, and dairy could be as harmful to health as smoking? One nutrition scientist replied that it was potentially dangerous because it could “damage the effectiveness of important public health messages.” Why? Because a smoker might think “why bother quitting smoking if my cheese and ham sandwich is just as bad for me?”

This reminds me of a famous Philip Morris cigarette ad that tried to downplay the risks of smoking by saying that if we think second-hand smoke is bad, increasing the risk of lung cancer 19 percent, drinking one or two glasses of milk every day may be three times as bad with a 62 percent higher risk of lung cancer. What’s more, doubling the risk is frequently cooking with oil, tripling our risk of heart disease is eating non-vegetarian, and multiplying our risk six-fold is eating lots of meat and dairy. So, they conclude, “Let’s keep a sense of perspective.” The ad goes on to say that the risk of cancer from second-hand smoke may be “well below the risk reported…for many everyday items and activities.” So, breathe deep!

That’s like saying we shouldn’t worry about getting stabbed because getting shot is so much worse. Or, if we don’t wear seatbelts, we might as well have unprotected sex. If we go bungee jumping, we might as well disconnect our smoke alarms at home. Two risks don’t make a right.

Of course, you’ll note Philip Morris stopped throwing dairy under the bus once they purchased Kraft Foods.


The IGF-1 story is so pivotal that it’s one of the first video series I ever produced for NutritionFacts.org. I’m so glad I was able to release this long-awaited update. If you want a blast from the past, watch the original series starting with Engineering a Cure.

For more parallels between the tobacco industry and the food industry, see:

What about the mobile phone industry? Does Cell Phone Radiation Cause Cancer?

For more on healthy aging and longevity, see:

It’s important to note the so-called low protein intake is actually the recommended protein intake, which is associated with a major reduction in cancer and overall mortality in middle age, under age 65. But did you notice that it says not among older individuals? All of this is covered in my video Increasing Protein Intake After Age 65.

In health,
Michael Greger, M.D.

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

Best Diet for Diabetic Neuropathy

Neuropathy, or damage to the nerves, is a debilitating disorder, and diabetes is by far the most common cause. Up to 50 percent of people with diabetes will eventually develop neuropathy during the course of their disease. It can be “very painful, and the pain is frequently resistant to conventional treatments.” In fact, currently, there is no effective treatment for diabetic neuropathy. Clinicians rely on steroids, opiates, and antidepressants to try to mediate the suffering.

But, as I discuss in my video Curing Painful Diabetic Neuropathy, a remarkable study was published 20 years ago on the regression of diabetic neuropathy with a plant-based diet. There are two types of diabetic neuropathy: a “relatively painless type characterized by numbness, tingling and pins-and-needles sensations” and a second form, which “is painful with burning or aching sensations to the point of excruciating, lancinating [or stabbing] pain.” This study concentrated on the painful type of diabetic neuropathy.

Twenty-one diabetics suffering with moderate or worse symptomatic painful neuropathy for up to ten years were placed on a whole food, plant-based diet along with a half-hour walk every day. Years and years of suffering and then complete relief of the pain in 17 out of the 21 patients within days.

Years and years of suffering and then complete relief of the pain in 17 out of the 21 patients within days.

Numbness noticeably improved, too, and the side effects were all good. They lost ten pounds, blood sugars got better, and insulin needs dropped in half. And, in five of the patients, not only was their painful neuropathy apparently cured, so was their diabetes. Their blood sugars were normal, and they were off all medications. Their triglycerides and cholesterol also improved, as did high blood pressure. In fact, it was gone in about half the hypertensives—an 80 percent drop overall in need for high blood pressure medications within three weeks.

Now, this was a live-in program, where patients’ meals were provided. What happened after they were sent home? The 17 folks were followed for years, and the relief from the painful neuropathy continued or improved even further for all except one person. How did they get that kind of compliance? According to the researchers, “Pain and ill health are strong motivating factors.”

Diabetic neuropathy is one of the most painful and frustrating conditions to treat in all of medicine, and 75 percent of patients were cured within days with a natural, nontoxic, and, in fact, beneficial treatment: a diet composed of whole, plant foods.

How could nerve damage be reversed so suddenly? It wasn’t necessarily the improvement in blood sugar control, since it took about ten days for the diet to control the diabetes, whereas the pain was gone in as few as four days. “There are several mechanisms by which the [‘total vegetarian diet’]…works to alleviate the problem of diabetic neuropathy as well as the diabetic condition itself.” The researchers’ most interesting speculation was that it could be the trans fats naturally found in meat, dairy, and refined vegetable oils that could be causing an inflammatory response. They found a significant percentage of the fat found under the skin of those who ate meat or dairy consisted of trans fats, whereas those on a strictly whole food, plant-based diet had none.

The researchers stuck needles in the buttocks of people eating different diets and found that nine months or more on a strict plant-based diet appeared to remove the trans fat from their bodies (or at least their butts). Their pain, however, didn’t take nine months to get better—it got better in days.

More likely, it was due to an improvement in blood flow. “[N]erve biopsies in diabetics with severe progressive neuropathy…have shown small vessel disease within the nerve.” There are blood vessels within our nerves that can get clogged up too. The oxygen levels in the nerves of diabetics were found to be lower than even the levels of de-oxygenated blood. This lack of oxygen within the nerves may arise from blockages within the blood vessels depriving the nerves of oxygen, presumably leading them to cry out in pain.

Within days, though, improvements in blood “rheology,” or the ease of blood flow, on a plant-based diet may play a prominent role in the reversal of diabetic neuropathy. Plant-based diets may also lower the level of IGF-1 inside the eyeballs of diabetics and decrease the risk of retinopathy (diabetic vision loss) as well. But, “the most efficient way to avoid diabetic complications is to eliminate the diabetes, and this is often feasible for those type 2 patients who make an abiding commitment to daily exercise and low-fat, whole-food vegan diet.” 

Why didn’t we learn about this in medical school? The “neglect of this important work by the broader medical community is little short of unconscionable.”


What about reversing diabetic vision loss? See my video Can Diabetic Retinopathy Be Reversed?.

Did you think trans fats were only in partially hydrogenated junk food? See Trans Fat in Meat and Dairy. Ideally, we’d reduce our intake as low as possible, which I discuss in Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero.

The best way to prevent diabetic complications is to prevent the diabetes in the first place:

And then to reverse it:

In health,
Michael Greger, M.D.

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

The Best Diet for Chest Pain

The Dean Ornish program that led to improved arterial function and the dramatic drop in angina attacks—a 91 percent reduction in reported frequency of angina—is not just about putting people on a plant-based diet. It also involves recommendations for moderate exercise and stress management. We know exercise alone can improve endothelial function, so how do we know diet had anything to do with it? This is the subject of my video Plant-Based Treatment for Angina.

Going back to Ornish’s first publication, he put cardiac patients on a plant-based diet, with no added exercise—just diet and stress management—and got the same 91 percent reduction in angina attacks within just 24 days. And Dr. Esselstyn was able to improve angina using a plant-based diet as the only lifestyle intervention. There are published case series going back to the 1970s documenting this. One study participant, Mr. F.W., had chest pain so severe he had to stop every nine or ten steps. He couldn’t even make it to his mailbox. He started on a strictly plant-based diet, and, a few months later, he was climbing mountains with no pain.

We know plant-based diets can reverse heart disease, dissolving away plaque and opening up arteries—in some cases without drugs or surgery—but that doesn’t happen in 24 days. “[T]he improvements in anginal symptoms are too rapid in onset and [too great] in magnitude to be explained by the gradual regression” of the atherosclerotic plaque. So, maybe it’s this improvement in function as well as structure.

What is it about plant-based diets that improves our arteries’ ability to dilate? Is it macronutrient differences? Simply the lack of the deleterious effect of meat? Maybe it’s the drop in cholesterol. Endothelial function improves if we lower our cholesterol low enough, by any means necessary. One study took PET scans measuring blood flow to the heart before and after three radically different ways to lower cholesterol. The first method used drugs, and the second used a low-fat diet—a really low-fat diet with less than 2 percent of calories from fat. And the third? No diet at all—that is, 90 days without food; the researchers had a central line placed to basically drip enriched sugar water straight into the subjects’ bloodstream for three months. These researchers were not messing around. The treatment protocol didn’t include any exercise or stress management, either. They wanted to isolate out the effect of cholesterol lowering on cardiac blood flow.

The study participants started out with miserable cholesterol levels and with diminished blood flow to their hearts, so-called perfusion deficits, areas of the heart muscle that aren’t getting adequate blood flow. After cholesterol lowering, their cholesterol levels were still terrible, but, with the improvement, there was an improvement in blood flow and their angina attacks were cut in half. When they stopped the treatment and their cholesterol went back up, the blood flow to their heart muscle went back down. So, cholesterol lowering itself appears to improve blood flow to the heart, and the researchers think it’s because when cholesterol goes down, endothelial function improves.

There’s a new category of anti-angina drugs, but before committing billions of dollars of public and private monies to dishing them out, maybe “we should take a more serious and respectful look at dietary strategies that are demonstrably highly effective for treating angina and that have also been shown to reduce subsequent cardiac morbidity. To date, these strategies have been marginalized by the ‘drug pusher’ mentality of orthodox medical practice; presumably, doctors feel that most patients will be unwilling or unable to make the substantial dietary changes required…While this may be true for many patients, it certainly is not true for all. And, in any case, angina patients deserve to be offered the very-low-fat diet alternative”—the Ornish or Esselstyn diet alternative— “before being shunted to expensive surgery or to drug therapies that can have a range of side effects and never really get to the root of the problem.”

In response, a drug company executive wrote in to the medical journal, “Although diet and lifestyle modifications should be a part of disease management for patients with cardiovascular disease and diabetes, many patients may not be able to comply with the substantial dietary changes required to achieve a vegan diet…” So, of course, everyone should go on their fancy new drug, Ranolazine. It costs thousands of dollars a year to take it, but it works. Collectively, the studies show that at the highest dose, Ranolazine may prolong exercise duration as long as… wait for it… 33.5 seconds!

It does not look like those choosing the drug route will be climbing mountains anytime soon.


See a comparison of the arterial function of vegetarians versus omnivores in my Plant-Based Diets and Artery Function video. How about comparing the Arteries of Vegans vs. Runners? If those on plant-based diets aren’t getting a regular, reliable source of vitamin B12, though, their artery health can suffer. See Vitamin B12 Necessary for Arterial Health.

Cholesterol may do more than just impair the function of our arteries. Check out the images in my video Cholesterol Crystals May Tear Through Our Artery Lining. For even more, watch How Do We Know that Cholesterol Causes Heart Disease?andOptimal Cholesterol Level.

Does Cholesterol Size Matter? Watch the video to find out.

Three things increase our cholesterol level: Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero. What about moderation? Well, how moderate do you want your disease? See Everything in Moderation? Even Heart Disease? to learn more. And, be sure to check out How Not to Die from 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, year-in-review presentations: