Cancer-Proofing Your Body
Written by: Michael Greger M.D. FACLM on January 31st, 2013

Lifestyle medicine pioneer Nathan Pritikin was an unlikely candidate to spark a nutrition revolution. He wasn’t a doctor or dietician but an engineer. As featured in my 2-min. NutritionFacts.org video Engineering a Cure, he reversed his own heart disease with a plant-based diet and went on to help millions of others. He even saved the life of my own grandmother, which is what inspired me to go into medicine.

Pritikin’s work has continued though his research foundation. Once Dean Ornish proved that Our Number One Killer Can Be Stopped, the focus shifted from heart disease to cancer. In my 3-min. video Ex Vivo Cancer Proliferation Bioassay, I describe an elegant series of experiments in which people were placed on different diets and their blood was then dripped on cancer cells in a petri dish to see which diet was more effective at suppressing cancer growth.

As you can see in the video, even the blood of those on a standard American diet (S.A.D.) fights cancer, but the blood of those on vegan diets fights about 8 times better. The blood circulating within the bodies of vegans appears to have nearly 8 times the stopping power when it comes to cancer cell growth. That was after maintaining a plant-based diet for a year though. Subsequent studies against breast cancer showed the power of eating plants for just two weeks. Watch The Answer to the Pritikin Puzzle to see the remarkable results.

This dramatic strengthening of cancer defenses was after 14 days of a plant-based diet and exercise—they were out walking 30 to 60 minutes a day. Although Pritikin started out reversing chronic disease through diet alone, later—to his credit—he added an exercise component as well. That’s great for the patients, but scientifically it makes it hard to tease out which intervention is doing what. Maybe the only reason their blood started becoming so effective at suppressing cancer growth was because of the exercise—maybe the diet component had nothing to do with it. This had to be put to the test.

In my 4-min. video Is It the Diet, the Exercise, or Both? I describe the experiment. Three groups were compared: a plant-based diet and exercise group, an exercise only group, and a control group that did neither. The diet and exercise group had been on a plant-based diet for 14 years along with moderate exercise as simple as walking every day. The second group was exercise and hardcore exercise at that: 14 years of daily, strenuous, hour-long exercise like calisthenics, but they ate the standard American diet. Which group was better at fighting cancer?

The researchers took petri dishes brimming full of human prostate cancer cells and dripped blood from each of the three groups on different dishes to see whose blood killed off more cancer. Watch the diet vs. exercise video to see actual photomicrographs of the effects on cancer cells. Basically they found that strenuous exercise helped, but nothing appeared to kick more cancer butt than a healthy diet.

Even though diet appears more powerful than exercise in terms of rallying one’s cancer defenses it doesn’t mean we can’t do both. In fact eating certain plants may even improve athletic performance—check out my video series that starts with Doping With Beet Juice and ends with So Should We Drink Beet Juice Or Not?.
Dr. Greger: Treating an Enlarged Prostate with Diet
in Diet & Nutrition, Videos / by Vegan Magazine / on February 5, 2013 at 2:24 pm /

Benign prostatic hyperplasia, or BPH—an enlarged prostate gland—affects 80% of American men over age 55, but like many other Western chronic diseases it appears to be a consequence of our diet. The majority of American men will develop a pathologically enlarged prostate gland. The good news is that like many other epidemics of chronic disease plaguing the Western world, it can be prevented and treated with a plant-based diet.

The Mayo Clinic website reports that “Doctors aren’t sure exactly what causes the prostate to enlarge,” but then they note that “It matters where you’re from. Prostate enlargement is more common in American and Australian men. It’s less common in Chinese, Indian and Japanese men.” Common sense tells us that it’s not where you’re from, but the diet of those countries.  Americans and Australians eat a diet high in saturated fat from meat, poultry, fish, eggs and dairy.  Asians generally eat a plant-based diet made up predominantly of rice and vegetables.

How Do Plant-Based Diets Fight Cancer?
Written by: Michael Greger M.D. FACLM on February 7th, 2013

Why do centenarians—those who live to be over a hundred years old—escape cancer? As you can see in my 3-min. video IGF-1 as One-Stop Cancer Shop, as we get older our risk of getting and dying from cancer grows year by year until we hit about 85 or 90, and then cancer risk starts to drop. It seems that centenarians are endowed with a particular resistance to cancer. So what’s their secret?

Every day, 50 billion of our cells die, and every day, 50 billion new ones are born. There’s a balance. Otherwise your body would shrink or get too crowded. Sometimes we need grow, like when we’re a baby or for that growth spurt around puberty. Our cells don’t get larger when we grow up; they increase in number. A child’s hand may only be made up of about 50 billion cells and may have to add half trillion or so while growing up.

Once we’re all grown up, though, we don’t want a lot of extra cells hanging around. We still need our cells to grow and divide, but out with the old and in with the new. We don’t want to be making more cells than we’re putting out to pasture. When you’re a kid, extra growth can be good; when you’re an adult, extra growth can mean a tumor.

How do our cells know when to tip the scale in favor of more dividing with less dying and when to come back into balance? A key signal is IGF-1, a growth hormone called insulin-like growth factor number one. IGF-1 levels go up when you’re a kid so you grow and then come back down when you’re done growing. Should your levels stay a bit too high as an adult, though, there’s a constant message sent to your cells to grow, grow, grow, divide, don’t die, keep going, keep growing. Not surprisingly, the more IGF-1 we have in our bloodstream, the higher our risk for many types of cancer.

When you’re a kid, growth is good, but too much growth when we’re all grown up can mean cancer. In my 90-second video, Cancer-Proofing Mutation, I describe Laron Syndrome, a type of dwarfism caused by congenital IGF-1 deficiency. Those affected don’t have that IGF-1 spurt in childhood so they grow up short-statured, but not having an excess of IGF-1 in their systems as an adult makes them nearly cancer-proof. This raises the question of whether one can achieve the best of both worlds by ensuring adequate IGF-1 levels during childhood and then suppressing excess growth promotion in adulthood. This can be done with a plant-based diet as I described in my last blog posts Cancer-Proofing Your Body and Treating an Enlarged Prostate With Diet, as well as in my 4-min. video The Answer to the Pritikin Puzzle.

Who is Pritikin? See Engineering a Cure. What’s the puzzle? See Ex Vivo Cancer Proliferation Bioassay. The binding protein findings I describe in the video may explain the findings in Is It the Diet, the Exercise, or Both?

For more on IGF-1, I’ve touched on it before in Dairy Hormonal Interference and Meat Hormones & Female Infertility

Vegan Men: More Testosterone But Less Cancer
Written by: Michael Greger M.D. FACLM on February 12th, 2013

Just a few days of walking and eating healthy plant foods can lower the level of the cancer-promoting growth hormone IGF-1 enough to reverse cancer cell growth in a Petri dish. This is detailed in my last three blog posts Cancer-Proofing Your Body, Treating an Enlarged Prostate With Diet, and How do Plant-Based Diets Fight Cancer?

We know decreasing animal product consumption decreases our IGF-1 levels, but how low do we have to go? How plant-based does our diet need to get? In my 2-min. video How Plant-Based to Lower IGF-1? the IGF-1 levels are compared between men and women eating conventional, vegetarian, and vegan diets.

Vegan men tended to have significantly higher testosterone levels than both vegetarians and meateaters (see graph here), which can be a risk factor for prostate cancer, the reason plant-based diets appear to reverse the progression of prostate cancer may be due to how low their IGF-1 drops (see Cancer Reversal Through Diet?).

Boosting cancer defenses within just days of eating healthy is a remarkable finding. For those interested in the whole story, I started out introducing Nathan Pritikin and the elegant series of experiments that became part of his legacy.

Researchers were able to demonstrate the mechanism by which a plant-based diet and exercise could suppress the growth of breast and prostate cancer cells and protect against prostate enlargement (more on prostate problems in Some Prostates are Larger Than Others and Prostate Versus Plants).

I also asked and answered Is It the Diet, the Exercise, or Both?

Finally, for those interested in whether lower levels of growth hormones in vegans might interfere with the accumulation of muscle mass, see my 3-min. video Plant-Based Bodybuilding.

–Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and F
Testosterone and Vegetarians

Guys are bombarded on the web now with the following formula:

Testosterone =  Meat

The corollary to this formula is that vegetarians (and vegans especially) must have lower testosterone levels than their carnivore counterparts. This kind of thinking permeates most popular health blogs and forums out there, especially on Paleo Diet and bodybuilding sites. In addition, almost every major men's health magazine, at least here in the U.S., have recipes and recommendations with meat front and center stage.  The message that guys get is clear:  if you want to be healthy and hormonal - you must eat meat.

The reasoning behind such thinking is fairly straightforward and goes something like this:

1.  Meat is full of saturated fat and the research shows that saturated fat is pro-testosterone.

2.  Vegetarian and vegan diets are higher fiber which also has been linked to low testosterone.

3.  Bodybuilding, a sport obviously highly dependent on testosterone, is completely dominated by carnivores.

I myself have discussed some these issues at length in my links on The Two F's: Fat and Fiber and Testosterone and Diet. 

So what do the studies show?  Well, first of all, saturated fat is definitely pro-testosterone and it is true that higher fiber diets have some linkage to lower testosterone. I myself have discussed some these issues at length in my links on The Two F's: Fat and Fiber and Testosterone and Diet. 

CAUTION:  Saturated fat slows down blood flow, something always less than desireable for sexually active males, and can destroys arterial health under most circumstances: read my link on The Potential Dangers of Saturated Fat for more details.

However, what I also bring up, and this is generally ignored by the bodybuilding and Paleo communities, is that vegetarian diets tend to have ample pro-testosterone monounsaturated fats. Even more importantly, vegetarian (and vegan) diets are also high in certain phytochemicals, which have some evidence for increasing testosterone, as I document in my link on Antioxidants and Testosterone.  Whole grains, fruits, vegetables, beans, legumes, nuts, seeds are the bulk of what most vegetarians eat and they are all packed with antioxidants, anti-inflammatories and other constituents that will protect and in some cases even stimulate those all-important Leydig cells.

Need to boost your Nitric Oxide naturally through food, drink and supplements? Check out Lee Myer's book here: The Peak Erectile Strength Diet

Or do you need the most comprehensive testosterone book in Amazon? Here it is: Natural Versus Testosterone Therapy

So who is the winner?  Well, to date there has only been one study that directly examined this question.  The researchers were primarily interested in comparing IGF-1 levels in vegans, vegetarians and meat-eaters, but also monitored a variety of other androgen-related hormones, including testosterone, as well. What they found was that vegetarians and vegans had average testosterone 6% and 16% higher than the carnivores, respectively. This, by the way, was after adjusting for important variables such as age and smoking status.[1]

The one variable that the researchers did not adjust for was BMI (body mass index) and when they did that, the vegetarians and meat-eaters had virtually equal testosterone and vegans were higher than everyone by about 6%.  Again, this flies in the face of almost everything you read on the web:  supposedly vegans and vegetarians do everything backwards and are loading up on toxic grains, fiber and all the things that will their slam manliness. In fact, though, the truth is that their testosterone levels are perfectly health and may even be higher on average than carnivores.  Either way, there is no evidence that vegetarians are suffering from a lack of androgens.

And this really is common sense.  Vegetarian diets have been studies extensively and there have been no signs that vegetarians have low testosterone whatsoever.  Furthermore, vegetarian (or very close) diets have been adopted by hundreds of millions of people around the globe and there are simply no signs of mass symptoms of low testosterone in these populations. In fact, one could actually argue quite the opposite:  cultures and societies that eat low quanitites of meat are known for their active sex lives later in life.  (See my book, the Peak Erectile Strength Diet, for other reasons that many plant foods boost erectile strength.)

It should also be noted that those in the study were in early middle age, which means that had lived long enough to accumulate damage to the Leydig cells, the hypothalamus and other key tissues that control and govern testosterone.  Therefore, it is possible that younger meat-eating males may have slightly higher testosterone but build up damage from some of the pro-inflammatory or other aspects of a meat-based diet.  We just don't know the answer to those kind of questions yet.

One very revealing aspect of the above study was that vegetarians and vegans both had very robust levels of SHBG, again significantly higher than the meat-eaters.  SHBG, Sex Hormone-Binding Globulin, is the protein tthat does just what its name implies:  it chemically bonds to most of the testosterone in your body.  Now that sounds bad, but researchers have noted that generally as SHBG increases so does total testosterone.

The Okinawans are another example that plant-based diets outperform meat-based diets in the long run.  The traditional Okinawans were actually not strict vegetarians, as they did eat some pork and fish.  However, the great bulk of their diet was always vegetarian and they ate relatively little fat, including saturated fat. Interestingly enough, they also consumed significant soy, which has fairly high levels of various phytoestrogens.

Yet, as I document in my link on How to Avoid Andropause, the average 70-year-old Okinawan has testosterone of 439 ng/dl, a very respectable number, and a direct contrast to the 346 ng/dl average level of the typical 70-year old American. [62] Just as remarkable is the fact that the typical Okinawan 100-year old has testosterone of 298, which is above the level considered hypogonadal. By any standards, Okinawans have delayed andropause by a couple of decades and are a further sign that the carnivore lifestyle is anything but superior when it comes to preserving and protecting one's testosterone levels..

What about the fact that bodybuilding is dominated by the carnivore lifestyle?  Bill Pearl says that after going vegetarian, he had the same amount of muscle that he did when he won his Mr. Universe titles.  Kenneth Williams, a vegan bodybuilder, placed third in the 2004 Natural Olympia bodybuilding competition.  And, of course, Mike Mahler is long time vegetarian and strength coach extraordinaire. The fact is that, if you desire, one can easily build a massive physique while on a vegetarian or vegan diet.