Obesity, cancer and bacteria in the gut: Scientists explore link – latimes.com

Obesity, cancer and bacteria in the gut: Scientists explore link

By Eryn Brown

June 26, 2013, 12:21 p.m.

It’s well known that obesity is linked to diabetes, heart troubles and other health woes, but studies have also linked carrying too much weight to an increased risk of some kinds of cancer, including esophageal, colorectal, pancreatic and other cancers.

Now researchers may have figured out why being overweight is linked to a person’s chances of developing liver cancer: obesity seems to cause key changes in microbes that live in the gut, stimulating bacteria there to secrete chemicals that damage DNA and lead to the development of tumors.

MORE ON MICROBES: Bacteria at the roller derby

Writing Wednesday in the journal Nature, a team of scientists led by Eiji Hara of the Japanese Foundation for Cancer Research in Tokyo described how they induced cancers (click here for report, subscription required for full text) in mice by treating newborn pups with a carcinogen known to produce various types of tumors.

Then they fed half of the mice a normal diet and half a high-fat diet.  All of the mice on the high-fat diet developed liver cancer; the mice on the normal diet did not.  Separately, the team also gave the carcinogen to mice that were genetically obese who were not fed the high-fat diet.  Those animals, too, developed malignancies — indicating that the obesity, and not the diet itself, was causing the cancers.

The team used a bioluminscent signal to track a chemical in the mice that promotes cellular shutdown as tissues age, finding that mice with the liver cancers had more of the chemical. The senescent cells had something to do with the cancers — and certain bacteria found in the obese mice, the team found in further experiments, secreted a bile acid known as deoxycholic acid (DCA) that damaged DNA and created the senescent state.

Treating the mice with antibiotics to wipe out the DCA-producing microbes reduced liver cancers.

“It is clear that the increased levels of DCA produced by gut bacteria play key roles in the promotion of obesity-related” liver cancer, the authors wrote.

In an editorial accompanying the study, Harvard researchers Suzanne Devkota and Peter J. Turnbaugh wrote that the Japanese scientists’ work presented “a plausible link” between DCA and liver cancer.

“Microbial bile-acid metabolism may provide an under-appreciated mechanism by which our decisions at the dinner table can translate to disastrous consequences for our health,” they wrote.

The study is just the latest in a wave of work detailing how the microbes that live in each of us affect our health, for better and for worse.  To learn more about the microbiome, check out recent stories in the Los Angeles Times on the fungi that live on our feet, the microbes that live on our dogs, and scientists who are studying gut bacteria.

via Obesity, cancer and bacteria in the gut: Scientists explore link – latimes.com.


Calories and gut bacteria – interesting read…

I just started taking microbiology and so found this especially interesting. In brief – some bacteria thrive under certain situations – like if you overeat, certain bacteria thrive and help you absorb more fat. Um scary? It’ll be interesting to see where research goes with this.

There’s a food fight in your guts. Not the Tater-Tot-chucking, spoonful-of-mashed potato-flinging, melee-in-the-cafeteria type of food fight. Rather, your intestines are the site of an ancient and complex war between your own cells and trillions of bacteria—a war over what happens to your food as it moves through your body. Some of the bacteria form genuine alliances with your intestinal cells, breaking down tough plant fibers that your cells cannot handle on their own, or chopping up lengthy caterpillar molecules into more digestible packages, in exchange for a portion of the day’s calories. Other bacteria lurk and loiter, sipping the nutrient-rich broth sloshing in your intestines as they wait for their chance to overrun your guts at the expense of your health. Every day, these microorganisms squabble amongst themselves for greater access to available nutrients. And sometimes your cells fight back, working extra hard to digest the food you eat before those persistent microbes help themselves to a disproportionately large serving. Studies suggest that the diversity of bacterial species in our guts partially determines how efficiently our cells process and store food and that, Continue reading

Alcohol and Weight Loss (Debbie downer time)

Alcohol and Weight Loss. by sparkpeople

Alcohol and weight loss are enemies, but an occasional drink can have a place in a healthy lifestyle. In fact, many experts note the potential health benefits of consuming a single drink per day, including a reduced risk for high blood pressure If, however, you are exceeding one drink daily, you might be sabotaging your weight loss plans.

Alcohol is metabolized differently than other foods and beverages. Under normal conditions, your body gets its energy from the calories in carbohydrates, fats and proteins, which are slowly digested and absorbed within the gastrointestinal system. However, this digestive process changes when alcohol is present. When you drink alcohol, it gets immediate attention (because it is viewed by the body as a toxin) and needs no digestion.

On an empty stomach, the alcohol molecules diffuse through the stomach wall quickly and can reach the brain and liver in minutes. This process is slower when you have food in your stomach, but as soon as that food enters the small intestine, the alcohol grabs first priority and is absorbed quickly into the bloodstream.

When the body is focused on processing alcohol, it is not able to properly break down foods containing carbohydrates and fat. Therefore, these calories are converted into body fat and are carried away for permanent storage on your body.

Chylo..wha? HDL, LDL and what are.

Science lesson time!

Here’s how you absorb lipids – and the end products.

Larger fat molecules are mixed with bile and become micelles. This allows fats to be moved to the intestinal cells. In intestinal cells, cholesterol and lipids are packed with protein. These are chylomicrons. Chylomicrons are released into the lymphatic system. They enter the bloodstream near the heart and then blood carries these lipids to the rest of your body for immediate use or storage.

As you know, fats and water don’t mix. Because proteins are surrounding the structure, these chylomicrons allow fats to be transported through the watery blood.

As the chylomicron goes through the body cells snatch up triglycerides from the chylomicrons and as it floats around it gets smaller and smaller. Eventually it gets back to your liver.

Here lipids your liver has been assembling and ones collected from the smaller chilomicron are packaged with more proteins as VLDL or very low density lipoproteins. This configuration is then shipped through the body again and cells again remove triglycerides, causing it to shrink. As triglycerides are taken up, the VLDL becomes mostly cholesterol. Now this is LDL (low-density lipoprotein). This continues to float through your body and pieces are taken up by cells.

Your body makes HDL (high-density lipoproteins) to remove cholesterol from cells and bring it back to the liver to be either recycled or to be disposed of. If you read my previous post you can see an instance where your body would need to collect some cholesterol.

For ways to raise your HDL levels, here’s a great article from about.com.