Study: Lots of Vegetables Can Lower Lung Cancer Risk

Matthew B. Schabath, Ph.D. led a team at the University of Texas in a case-control study that followed 1,674 patients with lung cancer with 1,735 matched healthy controls. From July 1995 through October 2003 they were surveyed to ascertain aspects of their health and diet. In their study released today in the Journal of the American Medical Association, researchers announce a correlation was found between plant-based foods and reduced lung disease. This is from an article describing the study on Intelihealth:

A diet higher in plant-derived compounds known as phytoestrogens is linked with a lower lung cancer risk, according to a study in the September 28 issue of JAMA.

Phytoestrogens are plant-derived nonsteroidal compounds found in soy products, grains, carrots, spinach, broccoli, and other fruits and vegetables, according to background information in the article. They have weak estrogen-like activity.

The three main classes of phytoestrogens are isoflavones, lignans, and cumestrans. A fourth group of plant-derived steroidal compounds believed to have estrogenic properties are the phytosterols.

Phytoestrogens have been shown to have a protective effect against some solid tumors, but there has been little epidemiologic research focused on dietary intake of phytoestrogens and lung cancer risk.

This is especially interesting in light of yesterday's article in The New York Times which questioned the ability of diet to play a role at all in stopping cancer.


Study: Soda Linked to Gullet Cancer

In the New Scientist, Shaoni Bhattacharya has news of a link between cancer of the esophagus and soft drinks from the Digestive Disease Week conference in New Orleans:

Mohandas Mallath, head of the digestive diseases department at Tata Memorial Hospital, India, and colleagues found a "very significant correlation" between the rise in consumption and esophageal cancer globally. The effects took about 20 years to come through, they believe.

The trend was seen in other countries where fizzy drinks have risen in popularity, such as the UK and Australia. But in countries where soft drinks have not caught on like Japan or China, there has been no increase in the cancers affecting the esophagus, the tube linking the mouth and stomach.

For more news about studies linking diet and cancer, be sure to read Dr. Fuhrman's post from yesterday.


NY Times Questions Diet as Cancer Prevention

In The New York Times today, Gina Kolata raises the question: can a healthy diet prevent cancer? After surveying the results of recent case control and cohort studies, she concludes that the benefits of a healthy diet are "hypothetical and elusive" when it comes to preventing cancer.

There's a lot of great research in Ms. Kolata's article, but unfortunately the studies she cites examine only modest dietary changes, over relatively short periods, in adults. A broader look at the research reveals a very different picture, and a convincing case that diet is an important tool in preventing cancer, especially in children and young people.

Understanding Different Kinds of Studies
There are different ways of studying the relationship between nutrition and cancer.
Epidemiological studies look at populations with varying characteristics for comparison. These have shown overwhelmingly that there is a connection between diet and cancer.
Case control studies compare two groups: one with the disease in question, and one without. (Past food intake is determined by questionnaires.)
Cohort studies follow two groups over time, looking for differences that appear years later.

As the Times acknowledges, hundreds of epidemiological studies show in any number of convincing ways that there likely is a connection between diet and cancer. In The China Study, for instance (which the Times earlier called "the Grand Prix of all epidemiological studies" and "the most comprehensive large study ever undertaken of the relationship between diet and the risk of developing disease") researchers compared the varying diets in various Chinese towns, and found that as the amount of animal products increased in the diet, even in relatively small increments, so did the emergence of the types of cancers that are common in the West. The researchers noted that most cancers increased in direct proportion to the quantity of animal products eaten and decreased relative to the amount of fruits, vegetables, and beans consumed. Areas of China with exceptionally low intakes of animal products were virtually free of the cancers and heart disease that develop in most people living in Western countries.

The China Study is one of many epidemiological studies showing a diet-cancer connection. Among those aged 50-75, cancers of the digestive tract, breast, and prostate are 20 times higher in the United States than in Laos, Cambodia, and Thailand. The huge geographic variability in the incidence of these cancers suggests dietary factors as the main cause. When people from a low-risk country migrate to the United States, their cancer rates increase considerably, and their offspring get cancer at the same rate as other Americans. This demonstrates that the lower incidence of these cancers in Asia is not due to a lower genetic susceptibility in Asians, but rather to the lack of exposure to Western lifestyles.

Fat, particularly animal fat, has been implicated as a cause of cancer, while the consumption of fruits and vegetables had been shown to protect against cancer. For instance, Boyd et al reported on this in a 1993 study published in the British Journal of Cancer, as did Steinmetz et al in a 1996 article in the Journal of the American Dietetic Association, and La Vecchia et al in a 1998 article in the European Journal of Cancer Prevention. Studies on laboratory animals also implicate omega-6 oils and saturated fat intake as cancer promoters. (Examples include Hursting et al in a 1990 Preventive Medicine article, Zhao et al in Nutrition and Cancer in 1991, Fay et al in Cancer Research in 1997.)

The Times article draws heavily on the many recent cohort and case-control studies that have been something of a fly in the ointment. They have created confusion and doubt, because with a few exceptions, they have not confirmed the findings of the epidemiological studies.

Case control studies have shown an association with animal fat consumption and cancer, but this was not considered convincing evidence, as patients with cancer have a tendency to exaggerate their prior fat intake on diet recall questionnaires.

The cohort studies are more respected because they follow separate groups over a long time period. The cohort studies have not shown a clear-cut relationship between dietary fat (even saturated fat) and cancers of the breast, prostate, and colon or have only shown a moderate relationship. The Nurses Health Study showed that American women who reduced their fat intake did not see a decreased incidence of breast cancer.

Why do the epidemiologic and cohort studies show different results? Do these conflicting results mean that saturated fat is not a significant risk factor for cancer? Is a high-fiber diet that includes large amounts of natural, unrefined plant foods such as fresh fruit, raw nuts and seeds, vegetables, and beans not protective? Is this huge amount of data collected in the China Project and other convincing epidemiological studies wrong?

Cohort Studies: Measuring Too Little, Too Late
Because all the epidemiological studies can't be wrong, there are two possibilities. The first is that these cohort studies followed adults who are past the age when diet plays a significant role. The middle-aged adults who attempted to eat more carefully to prevent cancer were already past the age when diet has its most powerful effect. In China, for example, the dietary pattern observed was present during gestation, infancy, childhood, and beyond.

The second possibility is that the lower ranges of saturated fat intake tested were not sufficiently low to be protective. The dietary variation from one group to another may not have been enough to show a significant difference. (For instance, people eating lots of pasta and chicken, but not lots of leafy green vegetables, beans, nuts, etc. would be considered to be eating a low fat diet, but they would not be eating the diet that the evidence suggests would be optimal for cancer prevention. As I explain elsewhere, they key to a healthy diet is nutrient density.)

The bottom line is that these studies on adults in Western countries are not very accurate. They follow adults who made only modest dietary changes later in life, and who were likely past the age when dietary influence can have a profound effect on cancer occurrence.

Childhood Diet is Key
The piece of the puzzle that The New York Times missed is the research relating to diets during childhood. There is a mountain of evidence that suggests diet among children, especially very young children, can have a strong effect on the likelihood of later cancer. A lot of the reason why I wrote the book Disease-Proof Your Child was to put that research together all in one place.

When you examine what children eat and its effect on cancer, epidemiologic, case control, and cohort studies all fall much more in line with the idea that a healthy diet can reduce the likelihood of cancer.

This makes some sense: the growing body, with its dividing cells, is at greater risk when exposed to all types of negative and toxic influences. With loosely spooled DNA, children are literally more exposed.

Researchers have noted many examples of events in youth that cause cancer decades later. For example, the largest groupings of cancer spikes among those who survived the Hiroshima and Nagasaki bombings occurred 40 to 45 years after exposure (according to Pierce et al in a Radiation Research article published in 1996.)

Also in Japan, a forty-one-year National Nutrition Survey detected a massive drop in dietary fiber after World War II. An average intake of 27.4 grams per day in 1947 was reduced to 15.8 grams by 1963. Fat intake increased form 18 grams in 1950 to 56.6 grams in 1987. Twenty-three to 24 years after the heightened consumption of animal products began, there was a correlating increase in colon cancer. Those with the highest consumption of plant fiber in childhood had the lowest incidence of colon cancer.

In a 1998 study published in the European Journal of Cancer Prevention, Caygill et al found that incidence of breast cancer correlated strongly with body weight---several decades before the cancer occurred. Those who were overweight as young women were more likely to get breast cancer. Some researchers conclude that dieting later in life may be too late.

Dr. Jerald Silverman of the Comprehensive Cancer Center at Ohio State University used a grant from the American Institute for Cancer Research to study mice who are very susceptible to breast cancer. He fed some a high-fat diet. Other groups he switched to low-fat diets at various stages of their lives. The study showed the same things we see in human studies: those mice fed the high-fat diet had more cancer, and more of the cancer spread to the lung. The earlier the change to the healthier lower-fat diet, the better the mice fared.

Breast cancer is not the only cancer that has been shown to behave in this way. Colon cancer has a weak association with obesity in adults. But high body weight in adolescence correlates much more strongly with eventual colon cancer, according to Must et al in their follow up to the Harvard Growth Study, which was published in the New England Journal of Medicine in 1992.

Engeland et al tracked 1.1 million Norwegian women, and found that women who were heavier and taller as youngsters were 56 percent more likely to develop ovarian cancer. Their results were published in the Journal of the National Cancer Institute in 2003. Similarly, Harvard Medical School researchers have found that women who reported being overweight by age eighteen were twice as likely to be diagnosed with ovarian cancer later in life.

Numerous studies report links between high caloric intake in childhood and cancer. Frankel et al reported in the British Medical Journal in 1998 that they studied 3,834 subjects for more than half a century, and found a positive association between calories consumed during early life and later mortality from every cancer other than those related to smoking. With every additional MJ/day (238 calories) there was a 20% increased risk of mortality from the most common cancers. Fewer calories consumed during childhood provided protection against all three common cancers. The researchers noted that their findings were consistent with similar animal studies and human studies showing correlation between height (which can be at least partly caused by high caloric intake, especially from high-growth foods like dairy) and cancer, and concluded that their study "confirms the importance of optimal nutrition in childhood."

Just as there are studies showing that diet during childhood can increase the risk of cancer, there are other studies demonstrating that certain foods can reduce that risk. For instance, Sullivan published research in Family Practice News showing that teenagers who eat more high-fiber, high-antioxidant foods such as fruits, vegetables, and nuts have a lower occurrence of benign breast disease, the precursor marker of breast cancer.

In countless studies, early puberty has been repeatedly associated with breast cancer. But what causes early puberty? Lots of research implicates childhood diet.

In 1998, the UK Department of Health's Working Group on Diet and Cancer of the Committee on Medical Aspects of Food and Nutrition Policy made public their cohort study showing that higher consumption of produce and protein-rich plant foods such as beans and nuts is associated with a later menarche, and the higher consumption of protein-rich animal foods--meat and dairy--is associated with an earlier menarche and increased occurrence of adult breast cancer.

Similarly, a 1999 study published by Berkey et al in the American Journal of Epidemiology followed children from birth and found that the girls who consumed more animal products and fewer vegetables between the ages of one and eight were prone to early maturation and puberty. The strongest predictor of early puberty was a diet rich in animal protein before the age of five. Many studies have shown convincingly that estrogen levels in children can be managed through diet.

Cho et al followed 100,000 women between the ages of 26 and 46, and found that the younger the woman was, the greater effect diet could have on later breast cancer incidence. Those results were published in the Journal of the National Cancer Institute in 2003.

These are just some of the ways that a healthy diet, especially for young people, can reduce cancer risk. As I describe in Disease-Proof Your Child, an excellent diet can also reduce exposure to pesticides and hormones--which have been shown in studies to have links to cancer. The book also explains how a diet rich in the healthiest foods can have a dramatic effect in reducing asthma, ear infections, allergies, cardiovascular disease, and autoimmune disorders.

Pomegranates for Your Prostate

The Daily Mail mentions a small study involving cancer in mice that has been conducted at the University of Wisconsin.

A total of 24 mice were divided into three groups. One was given normal water to drink, while the others had their water supplemented with 0.1% or 0.2% of pomegranate juice.

The doses were chosen to mirror how much juice a typically healthy person might be willing to consume daily.

The results were dramatic, the scientists said. Cancer progression was significantly slowed in mice receiving the higher pomegranate dose.

The study was mentioned on VegSource, which also links to a study from March showing pomegranates may help prevent heart disease, too.

When I first went to Dr. Fuhrman he told me to put a little bit of pomegranate juice--as well as ground flax, nuts, and fresh fruit--on my morning oatmeal. Especially if that fruit is blueberries, that makes for a delicious breakfast.

Study: Omega-3 Fatty Acids Prevent Cancer in Mice

The New Scientist has word of a study suggesting mothers can reduce their daughters likelihood of developing breast cancer by getting lots of omega-3s during pregnancy and breast-feeding:

Elaine Hardman at the Pennington Biomedical Research Center in Louisiana looked at the effects of mothers' diets on mice predisposed to develop breast cancer. Female mice whose mothers ate a diet rich in omega-6 fatty acids and which ate the same diet themselves after weaning all developed tumours by six months. The diets of most people in western countries are much richer in omega-6 oils than omega-3s.

In mice whose mothers ate a diet richer in omega-3s, or mice fed this diet only after weaning, tumour rates fell to 60 per cent. In female mice fed the omega-3-rich diet and whose mothers ate it as well, the rate fell to just 13 per cent, Hardman told a meeting of the American Association for Cancer Research this week.

Kentucky's Chronic Disease

Laura Ungar reports in today's Louisville Courier-Journal about the terrible state of things in Kentucky. The state is among the worst in the US when it comes to cancers, heart disease, diabetes, and other chronic diseases that are influenced by diet, exercise, and quitting smoking.

The title of her article is Bad Habits Give Birth to Chronic Diseases. The title implies the good news: changing habits can reverse chronic disease.

Ms. Ungar points out that the nature of fighting disease is shifting. It used to be that people got sick (with infections, etc.) and doctors cured them. The prevalant diseases at the moment, however, are not curable by doctors, but instead are best prevented with a long-term healthy approach.

Kentuckians would be much healthier if their major diseases were caused by germs.

Then a vaccine or antibiotics might prevent or cure what ails us.

But in the Bluegrass State, we suffer from such chronic illnesses as lung cancer, colorectal cancer, cardiovascular disease and diabetes � which are much more difficult to control because they are linked to harmful habits long accepted in Kentucky.

And we start down this road at a young age with habits that too often continue into adulthood.

The state ranks worst in the nation for teen tobacco use and above the national average for high school students who are obese. Adults smoke at the highest rate in the nation and exercise at the lowest rates. Many residents eat high-fat diets without enough fruits and vegetables, which combine with sedentary lifestyles to help make Kentucky the seventh-fattest state in America.

The article also quotes a nursing professor:

"It's ridiculous. It's just way out of whack," Ellen Hahn, a University of Kentucky nursing professor, said of spending on prevention. As a society "we don't value prevention. We just wait until a crisis happens and throw money at it."

Dairy, Fast-Growing Kids, and Cancer

Scientific studies have consistently repeated the observation that most common cancers are associated with stimulated growth in childhood, especially growth fueled by a diet heavy in growth-promoting animal products. This protein- and fat-rich diet is enabling today's children to exceed the height predicted by their parental genetics. But children who mature early and grow taller than expected by parental height have been shown to be at higher risk of breast, prostate, colorectal, leukemic, ovarian, and endometrial cancers.1

Animal models have displayed this phenomenon for decades.2 We now have the data to conclude that the same is true for humans. Growth can be equated with aging; slower growth leads to slower aging and longer life. We used to think rapid growth in our children was a beneficial phenomenon. "Drink your milk. It will help you grow big and strong," parents parroted to their children. Over the years, however, scientists have noted that animals that grow faster and mature quicker, die younger. Now we find that drinking "growth promoting" cow's milk in early childhood may have negative effects. Humans are designed to be raised on human milk in the first few years of life, not cow's milk. Human milk makes for slower growth. Cow's milk is specially designed for baby cows, and it supplies the nutrients to facilitate the rapid growth natural to cows.

Epedimiological studies consistently show low death rates from breast and prostate cancer where dairy consumption is very low.3 In areas of the world where breast-feeding is routinely continued past the second birthday, the intake of cow's milk is exceedingly low. It is likely that this combination of more breast milk and a much later introduction of cow's milk explains the results of these studies linking very low intake of dairy to lower incidence of breast and prostate cancer.

This passage is from the chapter entitled "Understanding the Causes of Cancer and Other Illnesses" from Joel Fuhrman M.D.'s new book Disease-Proof Your Child.

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