Monday, January 20, 2014

Health Research Recap (Week of 1/13/2014)

Those of you who think you may have Celiac disease but don't want to reintroduce gluten for weeks in order to damage your intestinal tissue enough to get a proper diagnosis via a biopsy may be in luck.  A new blood test is showing promise and can detect the disease after only 3 days of gluten exposure and results only took a day to obtain.  The test accurately predicted Celiac disease in people with the condition and did not show Celiac disease in people who do not have it.  However, the test needs to b researched on a larger scale before it will enter clinical use and a negative on the test does not necessarily mean someone is not sensitive to gluten, only that they do not have Celiac disease.  This test underscores how Celiac disease research really is in it's infancy, exposing a person to something that is thought to be severely damaging them in order to get a diagnosis is obviously not optimal, but it's all we have right now.

Researchers have found that humans and other primates burn 50% fewer calories than other mammals.  This likely accounts for the slower development seen in primates as compared to other mammals.  When humans are born, they are born fragile, take a year or more to be able to walk clumsily, and take upwards of 17-18 years to fully mature.  Compare this to a deer that takes minutes to stand and walk and is fully mature by age 5.  Of the primates, humans develop the slowest and our slow development is thought to be why our brains are more advanced and why we live to older ages than other primates.  Another interesting finding of this study is that primates in captivity expend the same number of calories as their wild counterparts.  This supports an earlier study showing modern human hunter gatherers burn basically the same number of calories as their more sedentary Western counterparts.  In other words, your 3 hours of exercise each week is having little effect on how much energy you are burning.

A study looking at both increased physical activity as well as decreased sedentary time found that this two pronged approach led to improved ratings of health and quality of life.  The study found that people who more active rated their health and quality of life as better than people who were less active.  In addition, those who reported sitting more rated their health and quality of life lower than those who sat less.  The results of the study underscore the importance of dealing with physical activity time(Often thought of as exercise) and sedentary time as two separate variables.  In other words, exercising is important, but sitting less throughout the day is equally important and long periods of sitting cannot be counteracted by simply exercising a little more.  Even just breaking up periods of sitting with getting up every once in a while can be a successful strategy to reduce sitting time.

Another study found that sitting for more than 11 hours a day increased all cause mortality by 12% in postmenopausal women. In addition, sitting for that long also increased the odds of dying from coronary heart disease, cancer, and cardiovascular disease by 27%, 21%, and 13%.  Sitting for long periods of time causes many negative physiological changes including reduced muscle mass as well as altered metabolism through changes in genetic expression, particularly with fat metabolism.

In obesity news, drinking diet soda causes overweight and obese people to consume more calories from food throughout the day.  Nothing new here, just phrased differently than this one, which basically says if you're going to drink soda it doesn't matter if you drink diet or sugar sweetened soda.  How about you just don't drink soda?

Aerobic exercise has been shown to protect against diabetes, and strength training has been shown to help manage Type 2 diabetes, the effects of strength training in preventing Type 2 diabetes in women have not been sufficiently studied.  A new study fund that strength training is beneficial in reducing the risk of type 2 diabetes in women and that a combination of strength training as well as lower intensity modalities such as aerobic training and yoga yielded the best results.

A new study in Type 2 diabetes identifies changes in "junk" DNA as being a causative factor in the disease.  The researchers found that sections of the "junk" DNA may be causing the genes responsible for producing insulin to be expressed improperly.  For years researchers threw away the "junk" DNA because they thought it was just that, junk.  This is because this part of the DNA does not code for proteins.  However, this area is now thought to be pivotal in diseases like cancer and Type 2 diabetes because this section of DNA is responsible for the way coding DNA is expressed.  While I believe these researchers are right for looking in this area, they are looking for genetic variants that make someone more likely to develop Type 2 diabetes.  While I believe this is worthwhile, I feel we should be looking at lifestyle factors that contribute to these changes so we can avoid them.  If genetic variants were the end all be all people would not develop Type 2 diabetes, they would be born with it.  "Junk" DNA is now known as the epigenome which can be changed via lifestyle, which I will discuss in one of my upcoming blogs in the series The human's guide to being human.

In a perfect segue from diabetes to gut bugs, a French/Swedish team of researchers has undercovered a way by which dietary fiber prevents obesity and diabetes.  It turns out the bacteria in your gut ferment these fibers in to the short-chained fatty acids propionate and butyrate that act on the intestine and causes it to produce glucose.  When glucose is produced in this way, even in the presence of a high fat/high sugar diet, a range of protective benefits occur via the brain.  This includes reduced hunger, increased energy expenditure, and reduced glucose output by the liver.  When mice who lack the ability to synthesize glucose in the intestine from these products of microbial fermentation are fed fiber, these protective benefits do not occur.  This points to fiber intake as being a very important factor in preventing the metabolic syndrome, and illustrates another way that your gut bugs are important to your health.

Yet another study looking at gut bugs found that high intakes of prebiotic fiber activate a receptor in the gut that dampens inflammation.  When your gut bugs ferment fiber, they produce a short chained fatty acid called butyrate.  When butyrate is produced in sufficient quantities, it activates a receptor in immune cells that reside in the colon, causing them to produce anti-inflammatory molecules and also signal other cells of the immune system to do the same.  This receptor is also found in fat cells and provides a protective benefit to the heart, but so far butyrate has only been shown to activate this receptor in the digestive tract.  Niacin has been shown to activate this receptor throughout the body, including the digestive tract, and can produce the same effect as butyrate in cells found there, even in a low fiber diet.

Looks like scientists have found a way to make fiber even better.  By creating a new "designer" fiber, researchers have come upon a way to slow the fermentation of fiber, allowing it to reach the more distal colon where common colon problems, including colon cancer and diverticulitis, often occur.  I could see this as a way to quickly turn around problems in the descending colon before they become bad, but this won't be a replacement for a high fiber diet.  It is also unlikely to be useful if your goal is to eat a mostly processed food diet and supplement with a little "designer" fiber.

A study looking at the benefits of probiotic use in infants has provided support for the use of a lactobacillus strain in infant GI disorders.  The study found that infants who were fed the probiotic strain L. reuteri DSM 17938 for their first 3 months of life had shorter bouts of crying, fewer regurgitations, and were constipated less than children not given the probiotic.  In addition, there was an approximate $120 average savings per family who used the probiotic over the 90 days due to reduced hospital visits.  There was an additional $140 savings to the community as well.

Finally...Jeff Leach, who is part of the Human Gut Project, is going to perform some pretty interesting self experimentation in the upcoming year.  He is going to follow several different diets for weeks and test have his gut microbiome to see how, and how quickly, his gut bugs change under different dietary conditions.  He is also going to live as a hunter gatherer and see how his environment affects his gut bugs as well.  I can;t wait to follow this one.  Here's a great write up in Science on the Human Gut Project.