Category Archives: Cancer

Eggs, Dietary Cholesterol, And Heart Disease

Dr. Greger is taking on eggs today (again):

So, do eggs and other sources of dietary cholesterol raise the risk for heart disease? Dr. Greger argues they do.

EggsScrambled2As I’ve come to understand, you have to look at the whole diet. For instance, for a given amount of saturated fat eaten, a given amount of dietary cholesterol (eggs) eaten at the same time will raise serum LDL cholesterol higher than if that dietary cholesterol was paired with a polyunsaturated fat, such as corn oil.1

Also, is any of that dietary cholesterol oxidized? Because if it is (and unless you eat it raw and very close in time to the demise of its source, some of it will be) it will contribute to the development of atherosclerosis and heart disease (and to the growth of cancer, as I just wrote). So says Fred Kummerow, a 98-year-old emeritus professor of comparative biosciences at the University of Illinois:

“Oxidized lipids contribute to heart disease both by increasing deposition of calcium on the arterial wall, a major hallmark of atherosclerosis, and by interrupting blood flow, a major contributor to heart attack and sudden death.”

And Professor Kummerow is of a mind that cholesterol is actually good for your heart! (Fortunately, our bodies manufacture all we need.)

Also, fruits and vegetables contain compounds that act as anti-oxidants, slowing further oxidation of consumed fats. You have to look at the whole diet.

You can’t judge well the effect of a single nutrient outside the context of the whole diet. It’s also risky to generalize the effects you may see of a nutrient in a small and perhaps homogeneous group. Nutrients, like dietary cholesterol, act differently in men vs. women, in old vs, young, in healthy vs. diseased (e.g. diabetes).

What is helpful, in my opinion, is to reflect upon the body of evidence. In this case, it looks like their exists a credible body of evidence to support limiting egg (and other dietary cholesterol) consumption.

1 Hypercholesterolemic Effect Of Dietary Cholesterol In Diets Enriched In Polyunsaturated And Saturated Fat, Atherosclerosis, Thrombosis, and Vascular Biology, 1994

Dietary Cholesterol Facilitates Cancer Development

AgedCheese3

The cholesterol in cheese, especially aged cheese, is prone to oxidation.

It looks like dietary cholesterol contributes to the progression of various types of cancers. I first saw it here:

Cholesterol Oxides And Carcinogenesis, Journal of Clinical Laboratory Analysis, 1991

“Experimental evidence indicates a relationship between cholesterol α-epoxide and skin cancer, and exposure of skin fibroblasts to ultraviolet radiation enduces formation of significant levels of this oxide. Colon cancer is also etiologically linked to cholesterol oxidation products. Higher than normal levels of cholestanetriol have been found in patients with colon cancer and also in those with precancerous disorders such as adenomatous polyps and ulcerative colitis. Higher than normal levels of cholesterol α-epoxide have been found in breast fluid aspirates of women with benign breast disease, with or without atypical hyperplasia of the epithelium, and this may be a factor in the increased incidence of breast cancer associated with hyperplasia. Similarly, the observed increased levels of cholesterol α and β-epoxides in prostatic fluid of men with benign prostatic hypertrophy may be associated with subsequent development of prostate cancer.

Although investigations into the role of cholesterol oxidation products in cancer are still in the early stages, evidence to date indicates a potentially significant role in the induction of some types of cancer.”

These authors wrote an entire textbook on this subject:

Biological Effects of Cholesterol Oxides, 1991

“In recent years, researchers have accumulated a growing body of evidence linking cholesterol oxides with human diseases such as atherosclerosis and cancer. This book presents what is presently known about the biological activities of cholesterol oxides and is intended to stimulate thinking in new areas of diet-heart or diet-cancer research.”

So… skin cancer, colon cancer, breast cancer, and prostate cancer are all linked to dietary cholesterol …  “dietary” meaning the kind we eat, not so much what our bodies make, because the cholesterol we eat is more vulnerable to oxidation – from exposure to air, heat, light, processing, radiation, and acids, e.g. stomach acids, and it is the oxidation of cholesterol which makes it more harmful.  According to Dr. Clark (see link below):

“Cholesterol oxidized by the body is negligible compared to oxidized cholesterol obtained from the diet.”

Why isn’t this common knowledge? How do groups that advise eating a high-cholesterol, high-animal food diet, like Paleo and Atkins, reconcile this?

A few more…

Promotion Of Carcinogenesis And Oxidative Stress By Dietary Cholesterol In Rat Prostate, Carcinogenesis, 2004

Researchers gave mice a diet supplemented with 1% cholesterol. For relativity’s sake, in humans, 1% of a 2000-calorie diet is 20 calories or about 2 grams of cholesterol. That’s about 6 or 7 times the recommended limit of 300 mg/day. So, these mice were getting a lot of cholesterol.

  • Rats on the high cholesterol diet developed adenocarcinoma in the ventral prostate more frequently (26% versus 4%).
  • Rats on the high cholesterol diet demonstrated a higher incidence of atypical prostatic hyperplasia (24% versus 4%).
  • These results indicated that long-term feeding of a 1% cholesterol diet promoted carcinogenesis and tissue oxidative stress in rat prostate.

Promotion Of Colon Carcinogenesis Through Increasing Lipid Peroxidation Induced In Rats By A High Cholesterol Diet, Cancer Letters, February 1996

Here, rats that were exposed to a carcinogen and then fed a high-cholesterol diet developed colon cancer at a significantly higher rate than those not fed a high-cholesterol diet. The authors speculated that “cholesterol may potentiate the carcinogenicity of [a carcinogen] in rats via an increase of lipid peroxidation and decrease in the activity of peroxidase in the target organ.”

Effect Of Dietary Oxidized Cholesterol On Azoxymethane-induced Colonic Preneoplasia In Mice, Cancer Letters, October 1992

Here, rats were getting just 0.1% cholesterol (about 220 mg on a 2000-calorie diet).  And “a dose-response relationship was observed in both mouse strains between the level of dietary cholesterol or oxidized cholesterol and formation of preneoplastic aberrant crypt foci. These anomalies were enhanced to a greater extent by oxidized cholesterol. This data shows a very strong effect of cholesterol in enhancing the development of preneoplastic lesions in chemically induced cells.

And finally… as I was searching for studies that addressed dietary cholesterol and cancer, I ran across this review article:

The Cholesterol Story: Are Your Fighting Heart Disease? John Clark, M.D, 2009

Clark says the same as the studies above, referencing them too:

“A high cholesterol diet depresses natural killer cells activity by 75%, making cholesterol a dangerous food if you want your immune system to fight off viruses responsible for pandemic flu, cancer or autoimmune diseases.  In fact, oxidized cholesterol increases the risk of skin cancer, colon cancer, ulcerative colitis leading to cancer, breast disease leading to cancer, and prostate hyperplasia leading to cancer.”

It’s just 8 pages, almost 3 of which contain over 300 references. He backs his claims meticulously.  Nonetheless, it’s quite readable. He accompanied it with some videos.  I have to say, his lecture is one of the most accessible I’ve come across on this topic.  Comprehensive, explanatory, and refreshingly lacking in the ego you see in lectures at universities and teaching hospitals … where, it seems, the number of acronyms filling a sentence is proportionate to the intelligence and credibility of the deliverer, or so the deliverer thinks.  (Note: Clark’s site is religiously affiliated.)

Clark concludes with a nod to a low-fat, whole food, plant based diet, a diet that eliminates all oxidized cholesterol. (Only animal food contains cholesterol, and that cholesterol, owing to its treatment before consumption, is oxidized to some degree.)

Folic Acid Supplements Increase The Risk For Cancer, Especially Lung Cancer

FolicAcidFortification2I’m going to couple my last post (Taking Vitamin E Supplements Increases The Risk For Prostate Cancer) with this post about the link between folic acid and cancer. Because people are also still taking folic acid supplements in this country (take a look at your multivitamin), even though this combined analysis of 2 large, randomized, double-blind, placebo-controlled trials (the gold standard of scientific investigation):

Cancer Incidence And Mortality After Treatment With Folic Acid And Vitamin B12, Journal of the American Medical Association, November 2009

… found:

“Conclusion: Treatment with folic acid plus vitamin B12 was associated with increased cancer outcomes and all-cause mortality in patients with ischemic heart disease in Norway, where there is no folic acid fortification of foods.”

There was a 21% increased risk for getting cancer and a 38% increased risk of dying from cancer. Lung cancers dominated. Patients who experienced increased risk were taking 800 micrograms/day (mcg/d) of folic acid.1 (They also took 400 mcg/d of vitamin B12 and/or 40 mg/d of vitamin B6.)

The recommended allowance (or DRI: Dietary Reference Intake) for folic acid in this country is 400 mcg/d. So they were taking twice the DRI. Yet they fell short of the tolerable upper intake of 1000 mcg/d.

In our body, folate is used in DNA replication; it’s needed for cell growth and repair. Cancer cells also use it for growth. “High doses of folic acid may speed cell division and increase tumor progression in preneoplastic lesions.”

Two items of note:

  1. Participants in these studies lived in Norway where there is no fortification of foods with folic acid. The US embarked on a mandatory fortification program in 1998 – flour and grain products here contain added folic acid. That’s in addition to the folic acid added to our breakfast cereals, often 400 mcg/serving. (A bowl of cereal and a typical vitamin pill can easily put you at 800 mcg. Eat anything made with folic-acid-fortified-flour and you’ll surpass their intake.)
  2. One mechanism put forth for the increased cancer rates was reduced activity of our immune system’s natural killer cells in the presence of high levels of folic acid.2 Coincidentally, high intakes of omega-3 (about 1 gram/day) were also seen to reduce the amount and activity of natural killer cells.

Taking vitamins is not as innocent as supplement manufacturers lead us to believe. But people still think a vitamin pill is harmless.

1 Folate found naturally in food hasn’t been shown to be harmful. Green leafy vegetables are a great source.
2 Unmetabolized Folic Acid in Plasma Is Associated with Reduced Natural Killer Cell Cytotoxicity among Postmenopausal Women, Journal of Nutrition, 2006

Taking Vitamin E Supplements Increases The Risk For Prostate Cancer

Note that this Vitamin E, the same type and strength used in this study that found taking it increased the risk for prostate cancer, is USP Verified. Less than 1% of dietary supplements are USP Verified. USP does not, however, vouch for a product’s safety or efficacy. The FDA doesn’t either. No regulatory body does.

People are still taking vitamin E supplements, either separately or as part of a multivitamin pill. They should know that this landmark study:

Vitamin E and the Risk of Prostate Cancer, The Selenium and Vitamin E Cancer Prevention Trial (SELECT), Journal of the American Medical Association, 12 October 2011

… found:

“Conclusion: Dietary supplementation with vitamin E significantly increased the risk of prostate cancer among healthy men.”

The study was big (35,533 men from 427 study sites in the United States, Canada, and Puerto Rico), and long (7 years: 2004 to 2011). It was designed to test whether taking vitamin E or selenium would prevent prostate cancer. Epidemiological studies suggested they might. Neither were found to prevent prostate cancer. And in the case of vitamin E, just 400 IU’s/day were found, to many people’s surprise, to increase the risk. The increased risk was statistically significant.

“Results: This report includes 54 464 additional person-years of follow-up and 521 additional cases of prostate cancer since the primary report. Compared with the placebo (referent group) in which 529 men developed prostate cancer, 620 men in the vitamin E group developed prostate cancer (hazard ratio [HR], 1.17; 99% CI, 1.004-1.36, P = .008).”

“The risk of prostate cancer at 7 years of median follow-up was increased by 17% in men randomized to supplementation with vitamin E alone, a difference that started to appear about 3 years after randomization. … The increased rate of prostate cancer in the vitamin E group was seen as early as 2006 and continued until the present analysis (HRs ranged from 1.12 to 1.17) suggesting that the current results are not an outlier observation due to multiple looks at the data.

Despite the lack of a mechanistic explanation, the findings show that vitamin E supplementation in the general population of healthy men significantly increases the risk of being diagnosed with prostate cancer.

This study only looked at prostate cancer. It couldn’t comment on other cancers. And it also couldn’t say if lesser doses were safe. 400 IU’s raises the risk for prostate cancer, but does 200 IU’s? 50 IUs? The following excerpt is going to hinder future studies that try to answer those questions:

“Furthermore, the fact that the increased risk of prostate cancer in the vitamin E group of participants in SELECT was only apparent after extended follow-up (allowing for additional events) suggests that health effects from these agents may continue even after the intervention is stopped.”

You could draw many assumptions from a study like this, and none of them, given this data, would support taking vitamin E supplements.

But this doesn’t stop people from taking vitamin E, “just to be safe” or “as an insurance policy against when I don’t eat right” or “to top off” their diet.  They say taking vitamins doesn’t do any harm and could help.  How do they know there is no harm?  And where is the evidence that these pills help us live longer? Or in better health?

I just came from Dr. Weil’s site, where he continues to advise taking 400 to 800 IUs vitamin E daily and says (as of 29 October 2012, a year after this study was published), in response to the question, “Are there any risks associated with too much vitamin E?” … “Except for an anticoagulant effect, vitamin E has no known toxicity or side effects.”

See my related post: Folic Acid Supplements Increase The Risk For Cancer, Especially Lung Cancer

New NYTs Article Uncouples Diet-And-Cancer Relationship. Huh?

DietCancerLinkAMythArticles such as this, which relegate the importance of diet in the prevention of cancer to a status of “myth”, are unfortunate:

An Apple a Day, and Other Myths, George Johnson, New York Times, 21 April 2014

The relationship between diet and cancer is, as Harvard’s Dr. Willett said, complex. That doesn’t mean it’s nonexistant. Just last week a study in the Journal of the National Cancer Institute found that consumption of a high fat, particularly high saturated fat diet was associated with an increased risk for breast cancer.

Johnson’s article itself mentions a point I’ve been driving home for years:

“Cutting back on milk and other dairy products might possibly lower the risk of prostate cancer.”

People like to read good things about their bad habits. Eating hot dogs, donuts, and chicken nuggets just got the green light!

Cancer On The Rise Around The World

Update: I’m adding this map of Global Meat Consumption because I believe it informs on the chart of cancer incidence below it:

GlobalMeatConsumption3
Source: GeoCurrents

Here’s The Economist’s Daily Chart on Cancer Incidence, from February 11:

GlobalCancerIncidence

Places with the highest cancer incidence are Australia/New Zealand, North America (United States), and Western Europe (Spain). Countries with the highest meat consumption are the same – Australia/New Zealand, the United States, and Spain. Per capita meat consumption in these countries is 10 times higher than countries with the lowest incidence of cancer.

The Economist says:

“[Globally], in 2012 14.1m new cancer cases were diagnosed and 8.2 million people succumbed. That is 11% more cases and 8% more deaths than in 2008. By 2025 the number of new cases is expected to reach 19.3m.”

That expected increase in cancer incidence coincides with an expected increase in meat consumption, especially in places that don’t eat much meat today:

“Demand for livestock products will nearly double in sub-Saharan Africa and South Asia, from 200 kilocalories per person per day in 2000 to some 400 kilocalories in 2050.”

I think there may be a relationship.

Breast Self Exams, Evidence?

I was reading Gary Schwitzer’s blog this morning. He offers, as usual, excellent public health perspective. His latest post was about breast self examination (BSE). The title sums up his post nicely:

“Check ‘em Tuesday” and CoppaFeel campaign strong on promotion, weak on evidence

Do BSEs save lives? The evidence isn’t there. Gary cites Dr. Margaret McCartney in the British Medical Journal:

Teaching women to examine their breasts regularly has been shown not to reduce deaths from breast cancer and actually increases the chances of a benign biopsy result.

Publicity campaigns that claim to be “against cancer” seem to get past much critical challenge, to our collective disadvantage. Public health messages should be based on evidence.

If we fail to critically evaluate campaigns on cancer, we create the appearance of doing something useful while potentially distracting from what might really help. In doing so we potentially harm the very women we’re purporting to help.”

Testicular cancer is the most common cancer in men 15 to 40 years old. And almost all men, by the time they reach the age of 80 will have prostate cancer. You would think that groups which believe self exams are helpful, with campaigns urging women to:

  • “Check ‘em and share pics.”
  • ONCE you’ve checked ’em, post ’em.
  • Put your snaps on Facebook or on Twitter and Instagram using the hashtag #checkemtuesday

… would urge men to do the same. Here are some guides for men in performing self exams.

Testicular:

Prostate:

And a brief wiki with photos on How To Check Your Prostate.

The “Check ‘em and share pics.” part gains new perspective.