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WCRF/AICR
Global Network

Issue 6 - July 30, 2008

Exploring Pineapple's Role In Preventing Colon Cancer

Laura Hale, M.D., Ph.D.Laura Hale, M.D., Ph.D., began working with compounds found in pineapple while completing her doctoral degree in immunology at Duke. Now an Associate Professor of Pathology and Director of the Laboratory of Oral Vaccine Development at Duke University, Dr. Hale’s research is uncovering pineapple’s possible role in preventing colon cancer.

In studying how certain cells bond and interact with one another, bromelain was the standard compound used to treat cells. Dr. Hale found that bromelain, a mixture of protein-munching enzymes in pineapple, was stripping cells of surface proteins involved in cell bonding (adhesion) and activation. That led to lab studies investigating how bromelain affects certain immune cells.

Applying bromelain, “was like the cell getting a haircut. It chopped off molecules and it turns out those molecules come back, but some come back fast and others come back slow.”

Stopping IBD Inflammation

After completing her doctorate, Dr. Hale focused on inflammatory bowel disease (IBD), which causes inflammation of the gastrointestinal tract, usually the  large intestine (the colon). Patients with IBD, especially the type that affects the colon (ulcerative colitis) have a significantly increased risk of developing colorectal cancer. Studies suggest that ulcerative colitis is related to a faulty immune system. Certain immune cells attack the body’s healthy cells and cause inflammation, which then may lead to colorectal cancer.

When Dr. Hale read a journal letter recounting how patients’ ulcerative colitis improved after taking bromelain, it pulled her past and current work together. The physicians who wrote the piece did not know why bromelain was helping, says Dr. Hale, but she had a theory. The bromelain could be chopping off the adhesion molecules, thereby not allowing the immune cells to adhere and turning off the immune response that causes colitis. “It was kind of a radical idea.”

The idea led Dr. Hale to launch a series of studies involving bromelain. In one lab study, she and her colleagues examined the effect of bromelain on cell surface molecules. They studied a range of white blood cells, and found bromelain stripped the cells of certain molecules involved with adhesion and activation. A later study showed that when mice ate bromelain, it remained active throughout the gastrointestinal tract. (Most enzymes like this are broken down in the digestive tract.)

PineappleInside the Pineapple

The standard bromelain used in studies comes from the bromelain-rich pineapple stem. The fruit also contains bromelain, but the proportion of the protein-digesting enzymes is different. When she talked about her work, said Dr. Hale, “I’d tell people bromelain comes from pineapple and their response would be, ‘what happens when I eat pineapple?’ I didn’t know.” Other questions also arose, such as how the activity of the individual enzymes differed and how fruit preparation may affect bromelain.

In an AICR-funded study, Dr. Hale is testing the fruit itself. Her two-part study is examining the anti-inflammatory effects of pineapple juice on cells in a test tube and on mice with ulcerative colitis. Working with the colitis-mice will allow Dr. Hale to conduct long-term animal studies on bromelain for the first time. She and her colleagues are measuring cancer development in mice drinking pineapple juice with water (which the mice find tremendously tasty, notes Dr. Hale).

The goal is to find treatments that help IBD patients and prevent them from developing colon cancer. Bromelain is one of several promising options Dr. Hale is investigating. “My goal is to identify whatever will work, and get it to the patients.”

 For information on the research about colorectal cancer’s links to diet, physical activity and weight management, AICR offers Reducing Your Risk of Colorectal Cancer.

CautionThe evidence suggesting that bromelain may help prevent colon cancer is still preliminary, says Sarah Wally, a registered dietician at AICR. While the research continues, AICR reiterates its recommendation not to rely on supplements to protect against cancer until more is known. Many supplements can interact with medications. Bromelain can have a blood thinning effect and may cause problems if taken with anticoagulant medications.

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News Roundup

Bitter Tasting Kids and BMIs

One factor that may play a role in childhood obesity could lie on the tip of your tongue, according to new researchLeave AICR.orgpublished in the July issue of Obesity. The study looked at the ability to taste a compound referred to as PROP, which is found in many vegetables, such as broccoli and spinach. Tasting PROP is determined by our genes. Researchers have long theorized that PROP tasters may shy away from eating many vegetables because of the bitterness, and thereby consume foods that may lead to weight gain. Yet studies linking PROP tasters to higher BMI are inconsistent. In the new study, after testing if 81 preschoolers could taste PROP and measuring their BMIs, the authors found that PROP tasters were significantly more overweight compared to non-tasters. The study focused on low-income children, who may not have parents with the resources to find vegetables the child might like, the authors note. The result could be the child eating less healthy but more preferable foods. Although the study found no differences in reported dietary intake, this may have been due to study design and is a further area to explore, the authors conclude.

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Eating by the Clock

Sometimes it seems the day ends without us taking the time to count how long we spent eating and drinking. Luckily, the U.S. Department of Agriculture has totaled the numbers for us in a continuous surveyLeave AICR.org that began in 2003. According to a new analysis using 2006 data, Americans ages 15 and older spent 67 minutes in an average day eating and drinking as the main activity. Add another 16 minutes eating and 42 minutes drinking beverages (everything but water) as a secondary activity – for example, while working, watching TV, or playing sports. There was no connection between BMI and if people ate more as their main or secondary activity. As for the men versus women: It’s a tie, with men and women spending about the same amount of time.

>In 2006, men and women spent about the same amount of time eating and drinking
Source: USDA ERS website

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Mediterranean for Cancer Prevention

Long studied for its link with heart health, the Mediterranean diet now has a large study suggesting the diet may prevent cancer as well. Published in the British Journal of CancerLeave AICR.org, the study looked at overall cancer incidence in more than 25,000 Greeks. After a median follow up of almost 8 years, the authors found that people who followed the Mediterranean diet – characterized by healthy fats, fish, whole grains, legumes, and hearty portions of fruits and vegetables – had a significantly lower incidence of cancer than those who least followed the diet. The more people adhered to the diet, the lower the cancer risk. It was the diet as a whole, not the individual components, that was linked to lower risk, note the authors.

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