These days there are so many nutrition studies being vomited out to the public by the media that it’s just too much to swallow. And that’s a good thing, since they are junk food for your brain.
There is a really big problem with nutrition research that makes it unreliable. It has to do with several variables that are ignored in virtually every study, unless it is specifically looking at these issues, which is rare.
The first issue deals with studies which assess the nutritional value of food. These studies analyze the composition of foods by breaking them down in the laboratory and measuring the quantities of the nutritional components, such as how much fats, protein, carbohydrates, and various vitamins and minerals it has.
It stands to reason that this type of analysis should consider whether the food is cooked or raw. Cooking can inactivate some vitamins and other heat sensitive nutrients, as well as some phytotoxins found in many plant-based foods, especially in beans. Cooking also helps to break down some complex carbohydrates and protein.
Of course, cooking is actually a chemical reaction process, and temperature matters. There are different products created by heating foods to boiling at 212 degrees F, versus roasting or baking at 350 degrees F.
For example, cooking carbohydrates above 248 degrees F causes the production of acrylamide, a nerve toxin and carcinogen. These products of cooking are not considered in most nutrition research, despite their impact on health. See Cooked to Death.
Nutrition research into food components usually considers whether the food is cooked versus raw, even if they do ignore the products of cooking that are added to the food.
What is not usually considered is what happens to the food once it leaves the plate or bowl and enters your mouth. How much of the nutrition in the food is processed and absorbed by your body after it passes your lips is anyone’s guess.
Digestion involves the further breakdown of food, and it begins with chewing. If you don’t chew your food well, and instead gulp it down in chunks, then you will minimize the exposure of food to all the digestive enzymes downstream that help you further digest it. Chewing is not only important for preventing choking, which is a real problem, especially for people who don’t have all their teeth, or take too large a bite. So you really need to begin your food’s journey down the alimentary canal with a good chew.
Chewing for a long time also adds lots of saliva to the food, which is the first exposure your food gets to a digestive enzyme. The enzyme is called ptyalin, and it attacks carbohydrates, converting starch to shorter chained sugars. This enzyme, however, needs an alkaline environment to work, and saliva is alkaline, so it works in your mouth. But once the chewed carbs get into the stomach, the environment becomes acidic, and this inactivates the ptyalin. So the longer the food is in your mouth, the more effectively you can break down carbs before they get to the stomach.
Once in the stomach, carbs have to wait while protein gets its first exposure to enzymatic digestion with the enzyme pepsin. Stomach acid is necessary for pepsin activation, which gets to work on these proteins. Meanwhile, the carbs and fats in the food are churning in the stomach along with the protein, waiting for things to breakdown enough to pass out of the stomach into the small intestine. (Large chunks of food must stay in your stomach long enough to get small enough to get through the sphincter that separates the stomach from the intestines, which is another good reason to chew your food thoroughly.)
In the intestines, stomach acid is neutralized by bile coming from the gallbladder, which lowers the acidity to allow other enzymes from the pancreas to work on the carbs, fats and protein. This digestion continues, but it clearly depends on how fast the food travels down the intestines, how well the food is mixed with the digestive enzymes, and how much enzyme your pancreas secretes into the intestines. It is affected by how healthy your liver and gallbladder are (the liver creates the bile that is stored in the gallbladder), and how healthy your pancreas is.
Further down the intestines, the resulting digested nutrients are finally able to be absorbed. This process is also dependent on the health of the intestinal lining, and on the blood supply to the intestines. This is why you need to rest after you eat. The process of digestion is hampered when you are physically active and shunting blood from the intestines to the muscles.
This is also why fast food is actually slow to digest. Food eaten on the run enters a digestive system that is on hold. If you are stressed while eating, your stress hormones slow digestion. And this can cause digestive upset, including gas.
And this raises the other issue ignored by nutrition research. The gas is produced by bacteria and yeast that live inside the intestines. They are your constant dinner guests, and they get first dibs on your food.
In fact, what you absorb from your intestines are actually the products of the microbial fermentation and digestion of that food. Your body helps to break the food down into sugars, amino acids, and fatty acids, and these are food for the microbes that call your guts home.
As a result, we end up absorbing the chemical products of bacterial and yeast fermentation and digestion. These are not considered in nutritional assessments of the food. For example, potatoes do not contain alcohol, but when you eat potatoes, the sugars are converted into alcohol by microbial fermentation, which shows in blood alcohol levels.
So you really don’t know what you are eating until you consider what your bacteria and yeast are serving you. We absorb these products and must metabolize and eliminate them from our bodies.
In fact, most of these bacterial products are volatile and you can smell them in the breath. And amazingly, the majority of the metabolites in your blood are from intestinal microorganisms.
Researchers have used breath analysis to study these and understand the impact of gut bacteria on our overall health.
Nutritional research into food nutrient availability ignores this microbial aspect of our digestion. This adds uncertainty to the nutritional value and impact of food.
Admittedly, it would be difficult to study this microbial variable, since it depends on the types of bacteria and yeast inside you, which can change with time. But microbial digestion of our food means that what we ultimate get from our meal is anyone’s guess.
As you can see, digestion is not the same between people, or even for the same person at different times. Each of the steps of digestion introduce inefficiencies in the process that impacts how much of the nutrition in the food you will absorb. Add to that the products of microbial digestion, and you can see how nutrition information is a guess, at best.
Of course, we can further disturb digestion with some drugs, especially Proton Pump Inhibitors, or PPIs. These drugs are given to people who experience excessive stomach acid, and impairs the ability of the stomach to produce acid. One major problem with this is that stomach acid is important. It serves to help activate pepsin to digest protein, but it also helps to kill bacteria in the food. Stomach acidity is high, and most bacteria don’t like that. So acid helps to control bacteria entering your body from the food.
And there’s more. Keep in mind that the bacteria in the intestines need to be managed, too. Stomach acid keeps these bugs from entering the stomach and going up your esophagus and into your throat. From there, these bacteria could enter the lungs and nasal sinuses and cause real problems. These are outcomes of a disease called Small Intestine Bacterial Overgrowth, or SIBO, and is a common side effect of using PPIs.
You can see why there is an increasing awareness of the role of intestinal bacterial in human health and disease. We live with bacteria, and they affect us. The digestive process feeds us and them. And what we get out of our food depends on which species of bacteria also came to dinner.
You can also now see how doing a laboratory analysis of a food product will not tell you what it really offers you in terms of nutrition, or in terms of microbial metabolic waste management. Reality is far more complex than a test-tube. And this is why nutrition research is usually unreliable.
If you’re fed up with bad research and its confusing results, then stop listening to the “experts” and start listening to your body. Your bacteria will also have a say. Ultimately, you will need to experiment with foods to see what foods make you feel the best. But keep in mind that your food preferences may change as your microbial guest list changes. And after taking antibiotics, all bets are off.
This all may be tough to swallow, so chew on this information for a while and mull it over until your mind digests it completely. Bon appétit.
References:
Breath volatile metabolome reveals the impact of dietary fibres on the gut microbiota: Proof of concept in healthy volunteers https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(22)00232-8/fulltext
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