Does banning hotdogs and bacon make sense?

Which of these sources will give you the most ingested nitrites:

467 servings of hotdogs

1 serving arugula

2 servings butterhead lettuce

4 servings celery or beets

your spit

The answer is obvious ... or is it?

How often do we hear advice to avoid processed meats — like hotdogs, bacon, ham and sausages — because they contain nitrates that have been linked to cancer? There is no safe amount of processed meats, the project director for the World Cancer Research Fund report told Dr. Albert Lim Kok Hooi of The Star this month. [Dr. Hooi’s article also claimed, ostensibly based on that WCRF report, that two-thirds of all cancers could be prevented if we were all thin, ate right and didn’t smoke. It advocated plaques at the entrance of all restaurants, school and office cafeterias warning: “Obesity causes cancer!”]

A campaign* to even ban hot dogs and other processed meats from school cafeterias in Austin, Texas, has also been in the news this month, with a local registered dietitian claiming that a single hotdog each day could increase colorectal cancer by 21%.

Since this is the last week of National Hotdog Month — and American Beer Month and National Ice Cream Month, for the full summertime meal deal — and a major international scientific safety report was recently published on nitrates in foods, which received very little media coverage, let’s look at this popular food concern.

As is nearly always the case, food fears are short on science and tall on misinformation. Many may remember that scare from the 1970s, claiming that nitrates could be carcinogenic, based on a report said to have found lymphatic cancer in 13 rats. Few consumers heard the rest of the story: that the preliminary MIT research behind that scare had had no peer review prior being acted on by the FDA and USDA, and was later discredited as faulty when an interagency working group of scientists from the FDA, USDA and NIH was convened to review the scientific data. The study was also sent to outside reviewers. As a 1983 risk assessment from the National Research Council noted, normal FDA review procedures hadn’t been followed during that scare, in what had seemed justifiable at the time to protect public health and in response to consumer group petitions; but “normal peer review would have revealed the fatal flaws in the MIT data.”

In 1981, the National Academy of Sciences reviewed the scientific literature and found no link between nitrates or nitrites and human cancers, or evidence to even suggest that they’re carcinogenic. Since then, more than 50 studies and multiple international scientific bodies have investigated a possible link between nitrates and cancers and mortality in humans and found no association.

What may be more surprising to learn is that scientific evidence has been building for years that nitrates are actually good for us, that nitrite is produced by our own body in greater amounts than is eaten in food, and that it has a number of essential biological functions, including in healthy immune and cardiovascular systems. Nitrite is appearing so beneficial, it’s even being studied as potential treatments for health problems such as high blood pressure, heart attacks, sickle cell disease and circulatory problems.

Brief history

Preserving meats using various salts has been practiced for thousands of years, even Homer’s era of 850 B.C. Salt works to kill aerobic bacteria, such as salmonella and E.coli on surfaces. But inside meats that are age-cured, the anaerobic environment enables Clostridium botulinum spores to thrive. Since around the Middle Ages, saltpetre (potassium nitrate) was used in curing meats, added both for distinct flavor and to preserve meat’s color, but it also blocks the growth of botulism and prevents spoilage and rancidity. The earliest printed cookbooks from the early 1700s show it used in astounding amounts, up to 50 times levels of nitrates and nitrites in more modern recipes. Even my old copy of Mrs. Beeton’s Book of Household Management by Mrs. Isabella Beeton, published in 1859, called for liberal amounts of salt and saltpetre.

TO CURE BACON IN THE WILTSHIRE WAY.

805. INGREDIENTS - 1–1/2 lb. of coarse sugar, 1–1/2 lb. of bay-salt, 6 oz. of saltpetre, 1 lb. of common salt.

Mode.—Sprinkle each flitch with salt, and let the blood drain off for 24 hours; then pound and mix the above ingredients well together and rub it well into the meat, which should be turned every day for a month; then hang it to dry, and afterwards smoke it for 10 days.

Time.—To remain in the pickle 1 month, to be smoked 10 days.

Sufficient.—The above quantity of salt for 1 pig.

Around the turn of the century, chemists realized that the active ingredient in saltpetre was the nitrite and this enabled sodium nitrite, in much smaller quantities, to replace saltpetre. This also greatly reduced the saltiness of the cured meats, which had to be soaked in water to be palatable. Nitrite levels in frankfurters were noted to be as high as 1,400 ppm before that change. Since 1925, when sodium nitrite was shown safe for humans, it has been approved for use in cured meats in the United States, and no cases of botulism have been associated with commercially cured meats since then. You’ll find being sold curing salts of sodium nitrate and nitrite (i.e. Morton’s Tender Quick) and Prague powders (#1 of 5.25% sodium nitrite and salt for cooked meats like lunch meats, hotdogs, hams and sausages; or #2 of 6.25% sodium nitrite and 4% sodium nitrate and salt traditionally used for longer dry-cured meats like uncooked bacon and salami).

Since 1974, the use of potassium nitrate and even sodium nitrate has been barred in commercially cured meats like hotdogs and pumped bacon by the USDA, as a precautionary reaction to that earlier scare; and only scant amounts of sodium nitrite are allowed since 1978, a mere 120 parts per million. But during the curing process, most of this nitrite forms nitric oxide, which binds to iron keeping the meat’s color pink, and the amount of nitrite remaining in the cured meats we eat has been shown to be only about 10 parts per million.

Sources of nitrates and nitrites

Nitrate, from any dietary source, does not accumulate in our body. Nor does nitrite.

Nitrite is formed in especially high amounts in our mouths from bacteria. Salivary nitrite accounts for 70-97% of our total nitrite exposure. Ingested nitrate (from foods and water) is converted to nitrite when it comes into contact with the bacteria in our saliva. About 25% of the nitrate we eat is converted to salivary nitrate, and up to 20% is converted to nitrite. Most absorbed nitrate is simply excreted in the urine within five hours.

In our stomach, nitrite then reacts to the natural flora and gastric contents, yielding nitric oxide, and little is absorbed. Moreover, what nitrite that is absorbed disappears quickly from our bloodstream, with the average half-life estimated to be as low as 1-5 minutes. More recently, the favorable role of nitrite and the formation of this nitric oxide in our bodies is beginning to be better understood (see below).

Nitrate undergoes a number of metabolic interconversions, absorbed in the proximal intestine and becoming part of the enterosalivary circulation, and is recirculated in the blood, recycled between the saliva and the gut. In other words, total nitrate and nitrite in our blood is almost identical to the nitrate levels, according to the scientific opinion issued by the European Food Safety Authority (EFSA), adopted on April 10, 2008.

The primary source of nitrites in our diets is vegetables, and to a lesser degree water and other foods. While it’s popularly believed that nitrates and nitrites mostly come from processed meats, they’re actually a very small source of our nitrite intakes, less than 5-10%. And nitrates aren’t present at all in commercially processed meats.

Nitrates occur naturally in vegetables and plants as a result of the nitrogen cycle where nitrogen is fixed by bacteria. Dietary studies around the world have found 70% (in UK) to over 97% (New Zealand) of human consumption of nitrates and nitrites comes from vegetables alone, regardless of organic or conventionally grown. On average, about 93% of the nitrites we get each day comes from the nitrates in vegetables.

So, to see how much nitrate people are eating and if people could be consuming too many vegetables and exceeding recommended daily intakes for nitrates, the Scientific Panel on Contaminants in the Food Chain of the EFSA by the European Commission just published its report on Nitrates in Vegetables in the June issue of EFSA Journal. They compiled 41,969 analytical results from 20 member states and Norway examining the nitrate levels in produce. Nearly every vegetable tested contained measurable amounts of nitrates, with averages varying from 1 to 4,800 ppm. For example, average levels were:

arugula 4,677 ppm

basil 2,292 ppm

butterhead lettuce 2,026 ppm

beets 1,279 ppm

celery 1,103 ppm

spinach 1,066 ppm

pumpkin 874 ppm

This compares to standard hotdogs or processed meats with average nitrite levels of 10 ppm.

By definition, cured meats must include the salts, sodium nitrite or sodium nitrate, so what about those expensive “nitrate-free” hotdogs and cured meats being sold to chemical-anxious consumers? They use “natural” sources of the very same chemical, such as celery and beet juice and sea salt. A chemical is still the same chemical, regardless of where it comes from. NO₃ = NO₃. They are no more free from nitrates and nitrites than conventional hotdogs.

So, when someone says that they avoid all foods with nitrates and nitrites (or that we should), they missed basic chemistry class.

The scientific expert panel went on to estimate how much nitrate people typically ingest, based on eating 400 grams (just under a pound, 14 ounces) of a variety of vegetables, along with water and 35-44 mg from cured meats a day. They calculated that the average person might eat as much as 157 mg nitrates a day. This is well within the Acceptable Daily Intake for nitrate, which is 3.7 mg/kg body weight/day (equivalent to 222 mg nitrate per day for a 60 kg adult) established by the former Scientific Committee on Food and confirmed by the Joint FAO/WHO Expert Committee on Food Additives in 2002.

The EFSA scientific panel noted that most people would actually consume less nitrate, as we usually eat half of our daily produce as fruits which have low nitrate levels; and processing (washing, peeling and cooking) would reduce levels more. This concurs with other estimates of nitrite and nitrate consumptions in the U.S. of 100 mg per day per person, according to the National Toxicology Program. The EFSA panel also noted that a small part of the population in some regions of the world eat only leafy vegetables which have especially high amounts, and could lead to the ADI being exceeded. But, there are no epidemiological studies to “suggest that nitrates from diet or drinking water is associated with increased cancer risk,” they wrote. Despite being the major source of nitrates, vegetables are considered part of a healthful diet and there’s no evidence to suggest vegetarians have higher risks for cancers, either. [Researchers have been suggesting since 1990 that the ADI be raised, but it hasn’t.]

The scientific panel’s review of the evidence found that the few studies suggesting a link between nitrates and cancers were of weak designs with “often very weak or even null” associations. The strongest studies and the body of evidence continue to find no increased risks.

Safety concerns

The safety of nitrates and nitrites in our foods and water has been taken quite seriously, and you could devote months to reading the hundreds of studies that have been done over recent decades examining potential health risks. The toxicology of nitrates and nitrites has been reviewed by numerous expert bodies, according to IPCS INCHEM, of the International Programme on Chemical Safety and the Canadian Centre for Occupational Health and Safety, which compiles international peer-reviewed chemical safety publications and database records from international bodies for public access.

The main toxic effect, although reversible, is methaemoglobinaemia. This is a rare condition when hemoglobin is oxidized to methemoglobin and becomes unable to transport oxygen to the tissues. Symptoms don’t become apparent until concentrations of methemoglobin reach 20% and can be fatal at very high concentrations (>50%), but is readily treated.

The levels of nitrites and nitrates said to be toxic are all over the place, as criteria for toxicity vary. But in general, toxic doses in the literature range from 2,000 to 4,000 mg for nitrate and 60 to 500 mg for nitrite. We're talking extremely high levels, far beyond what we would normally get in our diet without accidental poisonings or contamination. Studies on sodium nitrite even at doses of 30-300 mg as a medication for vasodilation or as an antidote in cyanide poisoning, for example, caused no toxic effects, according to the National Academies of Science.

Dr. G.J.A. Speijers at the Laboratory for Toxicology, National Institute of Public Health and Environmental Protection at Bilthoven, Netherlands, for example, described three patients with methaemoglobinaemia who had accidentally eaten meat with toxic levels of nitrites (10,000 to 15,000 ppm). Another case of methaemoglobinaemia was caused by accidental ingestion of 700 mg of sodium nitrite in water. Babies under 3 months of age, and people with certain hereditary enzyme deficiencies, certain medical diseases with lower gastric acids, and possibly the elderly may be at higher risks for methaemoglobinaemia and toxicity, several reviews have suggested.

So, how much is believed to be safe?

As with all toxicology and governmental health recommendations, remember that “safe” levels are not measures of safety, but of safety margins. So the ADI, as defined by the FDA, Joint FAO/WHO Expert Committee on Food Additives, and the European Commission’s Scientific Committee on Food, first took the NOEL level — the level where animal tests have shown no observable adverse effect over a lifetime of exposure — and then added a 100-fold safety margin to arrive at the most conservative level for human exposure.

So, while the NOEL for sodium nitrite has been reported in research at between 5-100 mg/kg/day, the ADI is less than 0.1 mg/kg/day. There’s a very wide safety margin.

Of course, any chemical, even ordinary salt, can be lethal at toxic doses. While the lethal doses of nitrite reported in the literature vary from 1,600 to 9,500 mg, the lethal dose of sodium nitrite, as per those Material Safety Data Sheets, is estimated at 1,000 to 2,000 mg.

This would equate to eating 2,222 to 4,444 hot dogs in a single meal. Even Joey Chestnut couldn’t do that!

Cancer strikes the greatest fear

Despite what’s still popularly believed, there is no evidence that nitrate or nitrite cause cancers in animals. And there is no evidence to indicate that nitrite or nitrate ingestion is carcinogenic in humans, either. Numerous international studies have attempted, unsuccessfully, to find any consistent or causative links between cancers or congenital malformations and nitrates or nitrites in food and water. “The majority of the studies revealed no correlation, or in some cases a negative correlation,” according to Dr. Speijers.

The 1981 scientific report from the National Academy of Science also concluded that there was no evidence to suggest that nitrates or nitrites cause cancer or are mutagenic. The National Toxicology Program, a division of the U.S. Department of Health and Human Services and considered the leading authority in the world on the safety of chemicals, conducted multi-year analyses at the request of the FDA. Its May 2000 and May 2001 reports “Toxicology and Carcinogenesis Studies of Sodium Nitrite,” also found “no evidence of carcinogenic activity” due to sodium nitrite. Sodium nitrite does not cause cancer in laboratory animals, these experts concluded, even when the animals are given massive doses in their water throughout their lifetimes. Also reported in the Carcinogenic Potency Database, research to date has found no link between nitrites and cancer.

While there remains no evidence for nitrite or nitrate carcinogencity, according to the National Research Council, the confusion among consumers may come from hearing cancer concerns raised about nitrosamines. As the IPCS-INCHEM notes, the sole cancer suspicion lies in the formation of N-nitroso compounds (NOCs), whether in the stomach or within the food itself, which have been shown carcinogenic in animals when exposed to high levels. Whether these compounds form in humans in normal dietary conditions in large enough amounts to pose a health risk, however, has not been established. In fact, as it turns out, the pH of our gastric juices doesn’t support nitrosamine formation and there are other substances in our body that inhibit their formation, too.

Nitrites and nitrates can combine with natural amines from proteins to form various NOCs. But the concentrations of nitrosamines in bacon and cured meat are at undetectable levels, according to the USDA. And that’s been known to be the case for more than a decade.

There are many different types of nitrosamines and their formation depends on multiple variables, such as other ingredients, processing, storage, cooking, bacterial counts, and more. It was discovered in the 1970s, however, that simply adding ascorbates (vitamin C, ascorbic acid, sodium ascorbate, erythorbic acid or sodium erythorbate) to the salt cure inhibits nitrosation reactions which could lead to the formation of nitrosamines in processed meats. Since the 1970s, all commercially cured meats use sodium ascorbate, as well as monitor nitrosamine formation in fried bacon.

Gastroenterologists in the UK also discovered in 1989 that the healthy human stomach itself secretes appreciable amounts of ascorbic acid in gastric juice which prevents endogenous (in our bodies) nitrosamine formation when we ingest nitrates and nitrites. Our bodies appear designed to safely eat levels of nitrates and nitrites typically in foods and water.

So, just as there is no credible evidence for higher rates of gastrointestinal cancers among vegetarians who eat lots of vegetables and high-nitrate diets, there has been no evidence of higher rates of cancers because people eat larger amounts of meats or processed meats.

“The public perception is that nitrite/nitrate are carcinogens but they are not,” said Dr. Nathan Bryanm Ph.D., with the Institute of Molecular Medicine at the University of Texas in Houston. “Many studies implicating nitrite and nitrate in cancer are based on very weak epidemiological data. If nitrite and nitrate were harmful to us, then we would not be advised to eat green leafy vegetables or swallow our own saliva, which is enriched in nitrate.”

Nitrites good for you?

As the EFSA report explained, nitrogen is the most abundant chemical element in the earth’s atmosphere. It’s a key component of essential biomolecules such as amino acids, vitamins, hormones, enzymes and nucleotides. Found in all living tissues, nitrogen is an fundamental part of the nitrogen cycle, which continuously interchanges nitrogen between organisms and the environment. Since nitrite is produced naturally in our bodies and also naturally comes from our foods, it shouldn’t be surprising that it is not only safe, but a necessary and normal part of human physiology.

As studies failed to support the premise that dietary nitrate is detrimental to human health, the benefits and function of nitrites began being recognized. In 1994, Dr. Jon Lundberg, M.D., Ph.D., of the Karolinska Institutet in Stockholm, and Dr. Nigel Benjamin of Peninsula Medical School in Exeter, England, independently noted that the human stomach holds large amounts of nitric oxide. Knowing that it weakens microbes, they suspected it might be killing germs in the stomach, too.

As researchers at the University of Aberdeen described nearly ten years ago in the British Journal of Nutrition, the oxides of nitrogen, that are formed in the acidic stomach after swallowing salivary nitrites, have antimicrobial action against a wide range of gastrointestinal pathogens, such as —

• Yersinia enterocolitica

• Salmonella enteritidis

• S. typhimurium

• Shigella sonnei

• E. coli O157:H7

• Helicobacter pylori

• Candida albicans

The antibacterial action increases with nitrate concentrations, they found. Gastric pH rises after food is eaten to levels that are not bactericidal against foodborne pathogens unless nitrite is present. So, nitrites appear to have a biological function to help protect us against stomach infections and foodborne illnesses. Dr. Benjamin also noted that cavity-causing bacteria die in high-nitrite environments and suggested that nitrite may play a role in preventing cavities.

The role of nitrites, saliva and nitric oxide in our body continues to be researched, most notably by fascinating experimental studies being conducted at the Karolinska Institutet and the National Institutes of Health in Bethesda, MD.

Nitrites are being studied for possible pharmacological roles in various medical treatments, including in hypertension, heart attacks and sickle cell. Doctors at Karolinska Institutet, for example, are looking at the role of nitrites for intubated intensive care patients (who don't swallow their saliva) in preventing ischemia-reperfusion injury, gastric ulcers, and cerebral vasospasms after subarachnoidal hemorrhage, and in neonatal pulmonary hypertension. A 2005 thesis by Dr. Håkan Björne, M.D. described this in detail.

Nitric oxide and S-nitrosothiols have been shown to have vasodilator properties (playing a role in regulating blood pressure) and modulate platelet function in the human body. Nitrite has been studied as a vasodilator in mammals for over 125 years, said professor Bryan. In 2003, scientists at the NIH conducted a physiological study to explore the circulatory role of nitric oxide, made in the body naturally from nitrite. Their small study of 18 healthy volunteers showed that intravenous nitrite could improve blood flow 175%, by opening blood vessels and increase oxygenation to tissues, making it “a potential new treatment for diseases like high blood pressure, heart attacks, sickle cell disease and leg vascular problems.” According to lead author, Dr. Mark Gladwin, M.D., senior investigator in Critical Care Medicine at the Department of the NIH Clinical Center:

Nitrite levels have been shown to be low in patients with high blood pressure... Nitrite helps get more blood to regions of the body with low oxygen, such as kidneys, the heart, the brain and muscles. This has potential as a new therapy that was previously overlooked. It's a powder sitting on the shelf and everyone has it.

Along these same lines, a 2005 study by scientists with the National Heart, Lung, and Blood Institute with investigators supported by the National Institute of Diabetes and Digestive and Kidney Diseases at Louisiana State University Health Sciences Center, found that sodium nitrite infusions led to the production of nitric oxide which increased blood flow and protected the hearts and livers in mice undergoing experimental heart attacks and liver injuries, reducing heart muscle and liver tissue damage.

All of this experimental research is preliminary but does illustrate that in the past 15 years, “we’ve gone from considering all of these things to be toxic and carcinogenic to realizing that [nitrites are] playing a fundamental homeostatic role,” said Dr. Ferric Fang, M.D., professor of laboratory medicine and microbiology at the University of Washington in Seattle. They’re a normal, natural part of a healthy body and not chemicals to fear.

So, hotdogs and processed meats are condemned as junk food because they contain nitrates, which they don’t, while vegetables are declared health food because they’re free from the same chemicals, which they’re not. It may be awhile before people will get to the point of calling bacon and hotdogs health food.

But, at the very least, said Dr. Gladwin, perhaps we should feel less guilty about eating hotdogs at the ball park.

There’s still plenty of summertime left and lots of regional hotdog specialties and BLTs left to enjoy, along with those garden vegies. With a little more science under our belts, hopefully everyone can enjoy it all with a lot less worry.

© 2008 Sandy Szwarc. All rights reserved.

* Led by The Cancer Project, of the vegan organization, Physicians Committee for Responsible Medicine, directed by Dr. Neal Barnard, M.D.. This group has been censured by the American Medical Association, unfavorably reviewed by the National Council Against Health Fraud, and an investigative Newsweek article revealed it actually had fewer than 5% physician members, as well as ties to animal rights groups.

Addendum: A reader sent this example of The Cancer Project's hotdog scares targeting children here.

Click here for complete article (and single page version).

JFS Exclusive: What’s the evidence cancers are our own fault?

We haven’t been able to turn on the television or radio or open a newspaper without being hit with news of the Second Expert Report just issued by the World Cancer Research Fund and American Institute for Cancer Research. The Report is called “Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective,” and is said to have found the most convincing evidence yet that being fat causes six cancers. Cancers, we’re told, “are mostly preventable” by following their diet and lifestyle recommendations.

Its press release, “Landmark report: Excess body fat causes cancer,” was reported around the world as if a script. The evidence “is clearer than ever. Even small amounts of excess body fat, especially around the middle, can make cancer more likely,” Dr. Emily Senay told viewers on the CBS Early Morning Show. “Never before has the evidence been more compelling and the advice more specific,” said Charles Gibson during ABC World News Tonight.

The Report issued the most stringent cancer-preventive recommendations of yet any organization, including limit red meat, high-caloric foods, alcohol, refined carbohydrates and salt; avoid sugary drinks, fast foods and processed meats; eat mostly a plant-based diet with at least 5 servings of fruits and vegetables a day; be active and stay as thin as possible within the ‘normal’ range of weight.

This Report may have impressed or frightened some because of its size, the numbers of experts involved, and the bold assertive claims that it was “the most comprehensive review ever published on the evidence linking cancer risk to diet, physical activity and weight.” But wade through the 517 pages and you will discover that not one of the key recommendations were supported in clinical studies. In fact, the Report not only failed to provide what most scientists would consider convincing evidence, its conclusions were often the opposite of the evidence.

Rather than take the word of experts or the media, let’s see for ourselves.

Meta-study

While CBS News said the authors had “analyzed more than 7,000 clinical trials” and USA Today called it “a landmark report,” it was nothing more than a giant meta-analysis.

“This is a technique for trying to get a convincing result by combining the results of a lot of unconvincing studies,” said Dr. John Brignell, Ph.D., a British scientist and engineer, publisher of Number Watch, and author of The Epidemiologists — Have they got scares for you!

This may be the world’s biggest example of the foibles of meta-analyses: pooling weak studies — all of which use different techniques, populations, time periods, measures and statistical models; few of which account for confounding factors such as socioeconomic status or smoking — hoping to create a significant effect. Or, trying to build a convincing case by the sheer number of studies. The authors chose which studies to include in their review and these were not all randomized clinical trials as many consumers may believe, but almost entirely epidemiological ones. As we know, these studies dredge through characteristics among populations looking for correlations, in this case to cancers. Of course, epidemiological studies can pull out thousands of meaningless associations that often contradict each other and this Report is filled with confusing contradictions.

Close examination also reveals that this Report repeatedly excluded from its review stronger studies which contradicted the panel’s recommendations. It also included only a handful of randomized controlled clinical trials, even when well-designed trials were available. There had actually been nearly half a million studies in their original literature search, but they pared it down to the ones they determined to be relevant. Only 2,471 cancer-related dietary studies were referenced in this paper (with another 1,363 related to process, opinion summations, or body composition/obesity theories), and many of those studies were repeats in several chapters. There were nowhere close to 7,000 studies referenced.

Methodology — defining the evidence

The authors with the World Cancer Research Fund Global Network acknowledged that they were the first cancer group to “create awareness of the relationship between diet and cancer” as highlighted in its first Report in 1997, and they worked from that predetermined belief and “what is already known.”

As they wrote in the Introduction:

The Panel is aware of the general consensus shared by scientists, health professionals, and policy-makers on the relationships between food, nutrition, physical activity, body composition, and the risk of cancer... It is abundantly clear that the incidence of all the common cancers in humans is determined by various potentially controllable external factors.... it means that cancer is, in large part, a preventable disease.”

They admitted that the methods used in this Report were new and others had been developed in their first Report. One of their tasks in this Report, they said, was to develop a method that “enabled evidence of relationships between diet, physical activity, body fatness, and associated factors, and cancer to be judged as causal, with varying degrees of confidence.”

But, correlations are never proof of causation. This needs to be repeated over and over again, said Dr. Brignell, because it’s one of the greatest contributions to confusion, scares and deliberate deceptions. Randomized, controlled clinical trials have long been recognized in the scientific process as the gold standard for determining causation. Countless times, interventional trials have proven beliefs based on epidemiological studies to be false.

The authors didn't use established epidemiological techniques but created their own method for proving causation from correlations, which they described:

The Panel endorses the view of the panel responsible for the previous report, that causal relationships between food and nutrition, and physical activity can be confidently inferred when epidemiological evidence, and experimental and other biological findings, are consistent, unbiased, strong, graded, coherent, repeated, and plausible. Individually, none of these factors is likely to be sufficient to infer a causal relationship with confidence.

How did they define associations as being causal? They created three grades of evidence:

· Convincing: Associations deemed as strong enough evidence to call ‘convincing’ of a causal relationship included: “at least two independent cohort studies...and a plausible biological gradient (‘dose response’) in the association. Such a gradient need not be linear or even in the same direction across the different levels of exposure, so long as this can be explained plausibly.”

· Probable: They defined associations as being strong enough to label as ‘probable’ of a causal relationship if it included: “at least two independent cohort studies, or at least five case control studies” and they could find a biological plausibility.

· Limited: The label of “limited, but suggestive” included associations “too limited to permit a probable or convincing causal judgement, but where there is evidence suggestive of a direction of effect. The evidence may have methodological flaws, or be limited in amount, but shows a generally consistent direction of effect. This almost always does not justify recommendations.” It included “at least two independent cohort studies or at least five case control studies.” And evidence labeled “limited, no conclusion” was that so limited no conclusion could be made.

But, as we’ll see, none of the relative risks reported in the epidemiological studies they used were strong enough to be valid, as defined by the National Cancer Institute (October 26, 1994), and credibly due to anything more than chance, statistical bias or the effects of confounding factors. Yet, they were sufficient evidence of causation in this Report.

The first line of evidence

According to their press statement, “the evidence that excess body fat increases the risk of developing cancer is much stronger now than ever before.” Expert panel member Phillip James, whose promotion of obesity issues is well known, as chairman of the International Obesity Task Force, said: “The most striking finding in the report is that excess body fat increases risk for numerous cancers. That is why body weight is the focus of our first recommendation.” So, their first recommendation was not just to be within the “normal” weight range of BMI 18.5-24.9, but to “be as lean as possible” within that range.

“The first lines of evidence suggesting that cancer is a largely preventable disease” are international variations and trends in cancers, these experts said. In Chapter One, twelve countries were profiled, including descriptions of the rates of cancer deaths, life expectancies and body mass indexes. But look at this data — do you see any support for their claims that BMIs near 18.5 means less cancer or longer life?

On the contrary, as BMIs slightly rise in each country, so do the average ages and life expectancies among the populations, but there is no relationship between cancer deaths and BMIs. The average BMIs in Egypt (with the lowest cancer deaths), for instance, are about the same as in Australia (with one of the highest cancer deaths) — but people live about 13 years longer in Australia. Average BMIs in India are the lowest they exampled, but men and women in the U.S. live 14 to 17 years longer. The Report supplied no support that the entire world needs to be on a diet to prevent cancer.

We can’t review each of the thousands of studies used in this Report — most of you have lives. So, we’ll look at some of the deadliest cancers and foods highlighted in this Report.

Breast cancer

These cancers are the fifth leading cause of death in women and the leading cancer-related death in women. The Report notes that this diagnosis is made more in high-income countries, and age is the most significant risk factor, with individual risk factors varying by age of menarche, childbearing and menopause.

Concerning body fatness, they used 43 cohort studies and more than 100 case-controlled studies but found the data “inconsistent.” Look closely at the relative risks of BMI for breast cancers reported in these studies — they all hug a relative risk of 1.0 (a null finding) on either side, and none approaches 3, essential to be considered tenable in epidemiological studies.

In discussing possible biological explanations, they suggested hormones might be a predominant mechanism, and described the theories by which fatness could prevent premenopausal breast cancer due to the role of progesterone and estrogen. Their selectivity was evident, however, when they rebuffed the preventive role of fatness, saying “there is no single well established mechanism through which body fatness could prevent premenopausal breast cancer.”

The panel concluded: “There is a substantial amount of consistent epidemiological evidence with a dose response relationship, but the mechanistic evidence is speculative. Greater body fatness probably protects against premenopausal breast cancer [but] the evidence that greater body fatness is a cause of postmenopausal breast cancer is convincing.” Interestingly, they say the same things about height (the other part of the BMI equation) as being a cause for breast and ovarian cancers. Fatness isn’t even mentioned as a risk factor for ovarian cancer, the seventh most common cause of cancer death in women.

Look again at their chart. Not one relative risk of BMI to breast cancers deviates sufficiently from 1.0 to be beyond what could happen by chance or statistical error. Convincing as a cause?

Lung cancer

Lung cancer is the single most common cancer and is the deadliest form of cancer in the world. The Report attributed smoking as being related to 85% of lung cancers and occupational exposures to carcinogens next. In lung cancers, they found the evidence linking dietary vegetables, red meat, processed meats, total fats and butter, like physical activity, to be limited and inconsistent. Evidence for dietary supplements was sparse and inconsistent. Body fat was found to be associated with a lower risk, but they discounted this relationship as possibly confounded by cigarette smoking.

Instead, they reported that pooled meta-analyses of cohort data suggested fruits might lower risk and concluded: “The evidence is ample and consistent. A dose-response relationship is apparent from both cohort and case control studies and there is evidence for plausible mechanisms operating in humans. The evidence that fruits protect against lung cancer is convincing.”

However, among the studies not included anywhere in this Report, for instance, was the massive study led by Dr. Walter C. Willett, M.D., at Harvard School of Public Health in the Journal of the National Cancer Institute reviewed here. Examining the data on 71,910 women and 37,725 men followed for 15 years, Willett and colleagues found no relationship between fruits and vegetables and cancer.

Look at their chart. Not one relative risk of fruit to lung cancers deviates sufficiently from 1.0 to be beyond what could happen by chance or random fluke. Convincing of cause?

Pancreatic cancer

While this is the ninth most common cause of cancer deaths, age-adjusted incidences have been stable since the 1970s, they reported. The Report found the evidence for all of the foods they considered, including red meat and fruits, or body fatness to be inconsistent and any correlations not beyond chance. Ample evidence examining coffee, for instance, “fails to show an association. It is unlikely that coffee has a substantial effect on the risk of pancreatic cancer,” they concluded.

Look at their graph. Do you see any appreciable differences between their admittedly untenable associations with coffee, and those between fruits and lung cancer above, which they claimed were ‘convincing’ evidence of preventing cancer? Of course not.

Stomach cancer

Stomach cancers are the second most common cause of death from cancer. Age-adjusted rates for these cancers are dropping and in 2002 were half of what they were just 30 years ago. The bacterium H.pylori and various infectious agents are associated with stomach cancers and the increased availability of refrigeration has likely aided the decline of these cancers, they reported.

In fact, in contrast to the Report’s conclusions that all cancers are largely preventable by diet, exercise and weight control, it actually stated that “approximately 1 in 4 cancers in low-income countries are estimated to be attributable to infection. In 2002, this represented some 1.9 million cancers or close to 1 in 5 of all cancers worldwide.” The role of diet comes in — not from eating too much, but — in ensuring people get enough to eat to prevent nutritional deficiencies which “can lead to immunodeficiencies and increased susceptibility to infections.”

In reviewing epidemiological studies surrounding fruits and vegetables, they reported nonsignificant relationship to stomach cancers, with none of the studies finding relative risks reaching relevance. The evidence for legumes, soy products, chili and other foods were limited and inconsistent. That included processed meats, smoked meats, and grilled or barbecued meats.

And what about salt, most popularly linked to stomach cancers? They reported that a “meta-analysis of case-control data showed an [untenable] 18 percent increased risk per gram of sodium per day; the meta-analyses for total salt indicated increased risk but were not statistically significant.” As they acknowledged, even in the higher-quality studies, confounding factors could explain the differences seen as “salt is inversely related to the availability of refrigeration in a population, and so to socioeconomic status, which is itself related to stomach cancer risk.” No food was related to this cancer, either.

Liver cancer

These tragic cancers are almost always fatal and are the third most common cause of death from cancer. Aflatoxins (which contaminate organic grains and legumes stored in moist, hot conditions) have long been recognized as a direct source of liver cancer and increase risks up to seven-fold. Hepatitis B and C infections are also a cause of liver cancer and about 80% of liver cancers develop in cirrhotic livers, they reported.

Not surprisingly, they found that any evidence for a role of fruits and vegetables, as well as body fatness, was sparse and inconsistent. Even no study of alcohol consumption they reviewed had been able to find statistically significant results. “The cancer disease path may be different in people with cirrhosis,” they noted, but studies were difficult to interpret. No food was related to this cancer.

Prostate cancer

This is the sixth most common cause of death among men. They reported that age-adjusted rates were increasing “largely because of the increased availability for screening for prostate specific antigen (PSA) in men...leading to the detection of many prostate cancers that are small and/or would otherwise remain unrecognized and which may or may not develop further into higher stage disease.” It is mainly a disease among high-income countries and risks increase with age, they said.

They found the evidence linking prostate cancer with legumes, soy products, processed meats, milk and dairy products, vitamin E or beta-carotene to be sparse or limited and inconsistent. Concerning foods containing lycopene, however, with no support they concluded: “There is a substantial amount of consistent evidence, in particular on tomato products, from both cohort and case-control studies. There is evidence for plausible mechanisms. Foods containing lycopene probably protect against prostate cancer.”

Not included in their review, however, were any of the studies examining lycopene and cancers discussed in a recent post, such as one conducted by the U.S. Food and Drug Administration (FDA) Center for Food Safety and Applied Nutrition which found no association between lycopene and any cancer evaluated. The Report also didn’t include the large study at the National Cancer Institute and Fred Hutchinson Cancer Research Center among 28,000 men enrolled in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. This ongoing, randomized NCI trial found no association between serum lycopene and total prostate cancers or aggressive prostate cancers.

Colorectal cancer

Cancers of the colon and rectum are the fourth most common cause of death from cancer and incidences are highest in industrialized, high-income countries. The Panel determined “that food and nutrition have a highly important role in the prevention and causation of [colorectal] cancers.” While they said that as many as 10% are the consequence of recognized hereditary conditions and another 20% occur in those with family histories, inflammatory bowel diseases and certain medications have also been shown to increase risks. Nevertheless, these cancers are most preventable by appropriate diets, they said.

Let’s look.

Dietary fiber is the dietary change most commonly believed to protect against colorectal cancers. Based on 107 epidemiological studies, they said that most found lower risks — but none were significant, including pooled analyses. “Therefore no effect can be attributed specifically to fibre,” they wrote. So what did they conclude in their recommendations? They pretty much ignored their own findings: “A clear dose-response relationship is apparent from generally consistent cohort studies, supported by evidence for plausible mechanisms, but residual confounding could not be excluded. Foods containing dietary fibre probably protect against colorectal cancer.”

This Report failed to include in its review five randomized clinical trials of dietary fibre that have been conducted. Not one has found fibre to be effective at reducing the recurrence of polyps or the occurrence of colorectal cancer. JFS recently reviewed these studies and others on dietary fiber and whole grains.

The Report found no evidence for a relationship between colorectal cancers and vegetables, fruits, fish, cheese and sugars. The evidence was all inconsistent and limited, even by their own admissions. Evidence for animal fats was limited, with the 5 cohort studies they reviewed and a meta-analysis all showing nonsignificant associations, they reported.

Concerning red meat, they found most of the 16 cohort studies they considered showed higher risks, but they only cited relative risks below relevance, such as 15% and 43%. Similarly, they claimed an equally untenable 21% higher risk had been reported in a meta-analysis of cohort data on processed meats, but they included very few studies, most of which were more than a decade old.

Despite no epidemiological evidence showing a tenable connection, they concluded that both red meat and processed meats are a “convincing cause of colorectal cancer.” The risks of processed meats were so severe, that they recommended people eat “very little if any.”

Oh really?

Here again, larger, stronger and newer studies were not included in this Report, including the largest meat study to date. For example, researchers at Harvard examined 14 studies on 725,258 people in North America and Europe investigating meat and fat and associations with colorectal cancer risk. As they reported in the Proceedings of the American Association of Cancer Research in 2004: “Greater intake of either red meat (excluding processed meat) or processed meat was not related to colorectal cancer risk.” This study was found nowhere in the list of references in this Report.

Also not included was the May 2000 or the May 2001 analyses “Toxicology and Carcinogenesis Studies of Sodium Nitrite,” by the National Toxicology Program, a division of the U.S. Department of Health and Human Services and considered the gold standard for determining cancer risks, which found “no evidence of carcinogenic activity” due to sodium nitrite. As also reported in the Carcinogenic Potency Database, the research to date has found nitrites do not cause cancer. While it’s popular among consumers to think that nitrates and nitrites mostly come from processed meats, in actuality they are a very small source of our intakes (less than 5%). Nitrates occur naturally in vegetables and plants as a result of the nitrogen cycle where nitrogen is fixed by bacteria. Dietary studies around the world have found 70% (in UK) to over 97% (New Zealand) of our daily consumption of nitrates and nitrites comes from vegetables. Nitrites used in cured meats, by the way, prevent the growth of botulism-causing bacteria and prevent spoilage that could make people sick. Since it was added to cured meats in 1925, there’s been no cases of botulism from commercially cured meats.

And concerning fatness, in the Report’s review of epidemiological studies, the associations they found weren’t even close to tenable — relative risks from a meta-analysis of an insignificant 15%. Yet, they concluded: “There is abundant and consistent epidemiological evidence with a clear dose-response relationship, and evidence for plausible mechanisms that operate in humans. The evidence that greater body fatness is a cause of colorectal cancer is convincing.”

Convincing of cause?

None of the recently reviewed studies, which showed no association between BMI and colorectal cancers, were included in the Report. These included the National Institutes on Health’s “Annual Report to the Nation on the Status of Cancer, 1975-2003,” which found that the incidences of colon and rectal cancers (despite increased surveillance) have been dropping among both men and women, as weights rise. Nor did the Report include the study by the Kansas Cancer Registry which found “obesity is associated with lower incidence rates of colorectal cancer.” Nor did it include the study of colonoscopy results for more than 3,000 adults conducted at 13 Veterans Affairs medical centers across the country.

We could go on, but you get the idea. Overall, none of the 17 cancers reviewed in this Report found even statistically meaningful associations with foods (sugars or sugary drinks, fats, meats, fruits, vegetables, legumes, vitamins, alcohol or processed foods) or body fatness.

Nor did it find evidence that losing weight, avoiding practically every food and beverage imaginable (except moldy, diseased foods), and eating their idea of a healthy diet prevents cancers. Did we mention that the Report also didn’t even consider the largest, longest randomized clinical dietary intervention trial ever conducted on ‘healthy’ eating? We already know what that one found, too.

Alan Caruba at the National Anxiety Center had it right when he made us laugh at all of this. As he wrote this week in USA Daily:

Eating Food Will Kill You

It is now a proven fact that eating food—any kind of food—will kill you. No one who has eaten food in the past is alive today and everyone currently eating food will die. Therefore, those noble people who seek to save us from eating every kind of food that the earth provides should be hailed and saluted for their efforts to keep us alive.

I say this as the son of a woman who taught the art of haute cuisine for over three decades and authored several cookbooks. That poor woman died at age 98 and I am convinced it was all that fabulous food that killed her. Ridiculous? YES!

© Sandy Szwarc. All rights reserved.

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