This is an odd and interesting bit of research. It relates to reaborption of nitrogen . . . and presents the possibility that more protein is conserved than previously thought. First dietary nitrogen 101: Nitrogen is a major component of amino acids. Amino acids are needed to form proteins. We can synthesize some amino acids ourselves, but others need to be obtained through diet. Dietary protein provides nitrogen and amino acids from plant or animal sources which are resynthesized into human proteins. Unused nitrogen is converted into Ammonia and Urea and excreted.
Can nitrogen be reabsorbed from the intestines?
The answer is a shocking “maybe.” A new nutritional study (published ahead of print in the Journal of Nutrition) has found that nitrogen appears to be reabsorbed. This makes little sense at first glance. Until we consider the vast populations of microorganisms that reside in the gut. Until recently, they were all thought of as “germs” that needed to be quashed. That has changed. We are learning more and more about how important they are for our health and even our survival.
The study is titled:
Nonprotein Nitrogen Is Absorbed from the Large Intestine and Increases Nitrogen Balance in Growing Pigs Fed a Valine-Limiting Diet.
Valine is an essential Amino Acid, so these animals were fed a protein-deficient diet. Then researchers administered urea or casein into the cecumof pigs. Let’s consider this research a step toward greater understanding of how nitrogen may be recycled in living animals. Not a new way to increase protein for strength. (Although who knows. It might work.) The urea was synthesized using Nitrogen-15. Dietary nitrogen is Nitrogen 14. Using nitrogen-15 lets the team know where the cecum-delivered nitrogen ended up.
Researchers found that more than 80% of the cecum delivered nitrogen was absorbed. Some of it was excreted in urine, but some was retained. This is a shocker. I know. Humans cannot synthesize protein using nitrogen. So WTF? The researchers propose that urea traveled through the bloodstream and into to the small intestine. Bacteria (some of which can make amino acids using urea or plain nitrogen) in the small intestine then used the extra urea to make amino acids. Amino acids produced by bacteria could then be absorbed the host (animals).
More research would need to be done to confirm that this happens. But it is very interesting. Humans vary in the types of bacteria they host. Bacterial populations vary according to diet, environment, chance (?) and who knows what else. Do people get extra protein from bacteria? Does this happen under normal circumstances (i.e. not piped in through the back end.)? One thing is sure: there is a lot to learn.
Columbus DA, Lapierre H, Htoo JK, & de Lange CF (2014). Nonprotein Nitrogen Is Absorbed from the Large Intestine and Increases Nitrogen Balance in Growing Pigs Fed a Valine-Limiting Diet. The Journal of nutrition PMID: 24647394
Exercise and weight are closely related. We all know that exercise burns calories and helps maintain body weight. Exercise has a lot of other health benefits. And maintaining a healthy body weight is important too. But ever wonder how gut microbes, exercise and weight interact? If you are like most people you will be thinking about such things as you wander the grocery store aisles, forgetting why you are there in the first place. Or you may wonder about how physical activity changes gene expression. Or how inactivity changes gene expression. You may wonder, as you pass the yogurt section, “what is with this probiotic stuff?” We’ll talk about probiotics another time.
Exercise weight and bacteria.
Exercise and weight are inter-related. But it looks like there is another player involved. (At least one and probably many.) It looks like exercise has influence over the bacteria that live in your digestive tract. Most of us have been taught that bacteria are bad. But they are not all bad. We need some species to help us digest food, access vitamins, stay healthy and defend us against evil germs. New research shows that the kinds of bacteria in the digestive tract differ depending on level of physical activity. The study was of mice. Mice may have been chosen for the project because it is more agreeable to pick up their poop and analyze it. You can scoop them into a flour sifter to remove the litter. And because you can easily control their diets. And keep them in cages with few complaints.
The researchers wanted to know how exercise, obesity, diabetes and gut microbes interact. The mice were placed in a cage with an exercise wheel. OR placed in a cage with an exercise wheel that didn’t work. After five weeks of exercising or not exercising animals were dosed with a common environmental contaminant. The chemical (PCBs) are known to impair glucose handling. They may also increase risk of diabetes. And a lot of other health problems. After dosing doots were collected. Little rodent poops are often called “doots” by the research community.
Mice who exercised had different kinds of bacteria in their doots. Bacteria from the digestive tracts of sedentary mice had a dramatic loss of proteobacteria and a hugely dramatic loss of Erysipelotrichaceae. The guts of exercising mice had many different kinds of bacteria.
What does this mean for us humans?
This research fits a piece into a larger puzzle. How are exercise and weight and bacteria related? People who are overweight have different gut bacteria profiles. The profiles change when a person loses weight. There are still many other puzzle pieces to fit And many that are missing. But it looks more and more that we need to move to keep our bodies running the way they should. And that things may go badly if we don’t.
Choi JJ, Eum SY, Rampersaud E, Daunert S, Abreu MT, & Toborek M (2013). Exercise Attenuates PCB-Induced Changes in the Mouse Gut Microbiome. Environmental health perspectives, 121 (6), 725-30 PMID: 23632211
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