Originally, I was going to talk about improving absorption from a performance stand point.
I thought – improve absorption to improve performance as more nutrients are made available as building material and for energy (helping weight loss and/or muscle gain).
Simple right? But reading around the topic, I quickly realised that overall gut health is as important, if not more important, for the average person – especially an athlete.
Why Should I Care About Absorption and a Healthy Digestive System?
Athletes eat a lot; way more than the average person. That’s cool – we need more calories.
Can you really absorb and assimilate all of the protein, carbohydrates and fats that you have been eating?
Imagine consuming 4000 calories and only absorbing let’s say 2000. Wouldn’t it be smarter to fix the underlying GI issue than taking in more food to get the calories in?
That has to put a downer on anyone’s mood, especially as you have just spent hours counting the carbohydrates in your broccoli and the precise weight of chicken breasts.
Kind of seems pointless doesn’t it?
My grandma has always said “To tinker with something, you need to understand how it works first”.
The basics are always a good place to start. You wouldn’t try to fix an engine if you have never seen a car before, would you?
A really brief 101 of the GI system
Gastrointestinal system: simply is a hollow tube from your mouth to your ass with stuff in between, forming the gastrointestinal tract.
The central function of the GI system is to assimilate nutrients and also regulate their distribution, storage and disposal.
- Oesophagus carries food from the mouth to the stomach where the food presence stretches the stomach- signalling to release gastrin and HCL.
- The stomach churns food into chyme and the pyloric sphincter prevents food entering the duodenum from the stomach until correct food consistency is reached.
- Pylorus opens, allowing chyme into the duodenum.
- The stomach is acidic (HCL from parietal cells) to aid digestion, but pancreatic enzymes need a basic environment to work (HCO3 – is secreted in bile).
- The duodenum is the first absorptive region of the intestine receiving the chyme from the stomach and mixing it with bile, pancreatic juices and enteric secretions.
- The pancreas produces the most of the digestive enzymes (proteases, amylases and lipases) which are synthesized as stored as inactive precursors to avoid self-digestion.
- Pancreatic secretion is stimulated by hormonal signals, mainly CCK (triggering gallbladder bile release) which is released when (particularly fatty) food enters the duodenum.
- The small intestine is covered in villi (finger like projections) and contains enterocytes on the luminal surface of the microvilli (increasing the area for digestion and absorption).
- The final stage of digestion occurs in the brush border of the enterocytes (synthesizes and secretes digestive enzymes to apical brush border) where disaccharidases and peptidases break down half-digested sugars and peptides to small monomers and oligomers for absorption.
- Transports proteins in the apical membrane and actively absorbs sugars and amino acids into the enterocyte.
If you prefer visual learning (she has some great lecture videos).
Finally the Good Stuff! What Happens to Absorbed Food?
Nutrients and hormones are carried by the portal vein to the liver from the small intestine where it removes ingested toxins or bacterial metabolism by-products – thus permitting the liver to control nutrition and metabolism.
A healthy person needs an adequate supply of nutrients to be able to build/repair tissues and as use for chemical energy (the use of nutrients depends on what the person does).
Macronutrients (carbohydrates, protein and lipids) provide energy and organic building material for the body.
Micronutrients (milligram quantities of vitamins, minerals and essential fatty acids) are required for specific biochemical functions.
Glucose is essential for energy supply to the brain. The liver can sustain blood glucose levels from stored glycogen (glycogenolysis) and by converting amino acids into glucose (gluconeogenesis).
When Shit Hits the Fan – The Low Down on Gut Problems
The GI tract epithelium needs to be protected from damage as it faces everything we consume: the good, the bad and the weird.
The main cause of macronutrient malabsorption is celiac disease and chronic pancreatitis (enzyme deficiency).
Pancreatic exocrine insufficiency may result in malabsorption of food, diarrhoea, fat rich stools, weight loss and nutritional deficiencies.
A good example is lactase deficiency which can cause lactose intolerance. Lactase enzyme digests the milk disaccharide lactose.
No lactase means that consumed lactose sits in the intestine causing an osmotic load. More fluid remains in the intestinal lumen and which is later excreted (diarrhoea).
We have an immune response to pathogens, and so does the intestine, it also needs to prevent reacting to food antigens (foreign proteins to the body) to avoid allergies and hypersensitivities.
The body recognises that food antigens are usually harmless and generally don’t produce an immune response. The liver contributes to this and antigens injected into the portal vein also encourage tolerance.
Chronic immune activation by H. pylori (gastric ulcers) or by coeliac disease (hypersensitivity to gluten proteins), can lead to excess production of immune cells.
The gut microbiome is responsible for about 70% of the total immune response in our bodies (Hunter, 2012).
Each person is not only a bag of human cells, but also a container for many symbiotic species (Elizabeth et al., 2012).
The commensal (a non- harmful co-existence) flora bacteria (good and bad) of the gut are essential and play a variety of important roles in human health and disease.
The abundant and diverse microbial members play critical roles in the maintenance of human health by liberating nutrients and/or energy from otherwise unusable dietary substrates, promoting differentiation of host tissues, stimulating the immune system and protecting the host from pathogen invasion (Elizabeth et al., 2012).
The disappearing microbiota theory tries to explain the modern day rise in allergic and autoimmune disease. It suggests that modern developments (like antibiotics, clean water, toxins etc.) have contributed to a shift in the species and types of microorganisms in the gut (Hunter, 2012).
This change has tinkered with our symbiotic relationship with our gut microflora and health benefits that they provide (Hunter, 2012).
The microbiome is implicated in IBS and it can extend beyond metabolic disorders to include disorders elsewhere in the body (Hunter, 2012).
For example, some by-products can include neurotransmitter like molecules (GABA and ammonia) which can interfere with mental functions.
Bad bacteria deprives a person’s body by metabolising nutrients that otherwise would be utilized by the digestive system and converted to energy; bad bacteria also produces extra intestinal gas- which can eventually lead to mucosal destruction causing malabsorbtion.
Symptoms: abdominal pain, gas and bad breath.
Defects in Intestinal Barrier Function are Associated with GI Tract Diseases.
The ability of the intestinal epithelium to function as a barrier between the external and the internal environment is very important in human health (Camilleri et al., 2012).
An increase in gut permeability allows the passage of bacterial antigens and activates the innate immune system.
Increased gut permeability is associated with inflamed bowel disease (IBD) and celiac disease and functional bowel disorders like IBS.
* Increase in permeability usually occurs before the development of colonic disease; prevent it and you could theoretically prevent bowel diseases (Camilleri et al., 2012).
Abnormal intestinal permeability is not necessarily sufficient to induce disease as other defects also need to take place (Camilleri et al., 2012).
The barrier (not always physical) consists of:
- HCL and pancreatic juices degrade bacteria and antigens.
- Commensal bacteria.
- Water, glycolyx and a mucus layers.
- Paneth cells secreting antimicrobial substances.
- Enterocytes secreting IgA.
- Tight junctions.
According to Camilleri et al, during stress and inflammation, mast cell mediators (TNF-α, tryptase, NGF and interleukins) may affect epithelial cell permeability by affecting tight junction proteins or uptake through the cell by disturbing the barrier to antigens and bacteria.
Mast cells also release serine proteases which can cause further tight junction breakdown and increased permeability.
Microbes can directly modify tight junction protein expression and localisation (through the release of soluble proteins, toxins or substrates) increasing gut permeability (Camilleri et al., 2012).
Microbes can also alter epithelial permeability indirectly through effects on host immune cells and cytokine release which can both decrease (TNFα, IFNc) or increase (TGFβ, IL-10).
Turning Your Gut in to a Bulletproof Cement Mixer – Fixing Damage and Turbocharging Normal Gut Function
“First, go see a doctor so that they can diagnose and treat any serious underlying conditions that you might have!”
Diarrhoea can be symptomatic of serious underlying GI diseases such as IBD, colorectal cancer or increased gut permeability (get it checked out).
1) Chew your food, don’t just scarf it down.
2) Digestive enzymes- not only if you have a low level naturally.
Taking them after big meals can alleviate bloating discomfort and I take them on my massive cheat-carb-weekend-orgy-days (absorb and assimilate more of your food).
The enzymes enable food to be broken down to small monomers at physiological temperatures (enzyme catalysis).
3) Drink enough water – constipation due to dehydration-can alter the balance of bacteria, causing intestinal inflammation.
4) Understand medicines impact on gut health.
Antibiotics kill good and bad bacteria.
Prostaglandins (PGE2 and PGI2 synthesized by COX-1) regulate intestine mucosal integrity, so their inhibition causes GI disruption.
NSAIDS inhibit the COX enzymes (used as anti-inflammatories and to reduce pain and temperature) by inhibiting prostaglandin synthesis.
Prostaglandins (lots of different ones) have various functions; one is to cause an inflammatory response.
The anti-inflammatory action of NSAIDS is due to COX-2 inhibition.
Older NSAID are non-selective (inhibit COX-1 and 2 enzymes) – aspirin, ibuprofen, paracetamol.
5) Consider HCL supplementation for low gastric acid in the stomach (and a lot of people do) and for performance gains.
Poliquin explains that indirect symptoms can include lack of results from training, inability to lose fat, and fatigue.
- The slowing of the body’s basal metabolic rate associated with hypothyroidism.
- Autoimmune disorders where the antibody production against parietal cells which normally produce gastric acid.
- The use of antacids or drugs that decrease gastric acid production.
- A symptom of H. pylori infection which can decrease the secretion of acid to aid its survival.
Direct symptoms can include belching, bloating after eating, indigestion and constipation due to undigested food, bad breath, acne, malabsorption and food allergies.
HCL supplementation can be used by athletes to help aid the digestion of mammoth food intake by increasing stomach acidity for optimal digestion, to break down and absorb vital proteins and nutrients.
Pepsinogen (a precursor enzyme) is converted to pepsin (protein digesting enzyme) in HCL presence which converts proteins to amino acids.
Improved absorption and digestion of proteins will support protein synthesises when trying to increase muscle mass.
It can also help with energy levels if you’re feeling chronically fatigued as you should increase nutrient absorption.
Insufficient HCL can cause macronutrients to pass into the small intestine and putrefy instead of being digested (nice).
6) Make note of what makes you feel like you just have been hit by a car.
Which foods send you sprinting towards the toilet or make you bloated or give you nasty protein farts?
Also the “perfect diet” might not be as perfect as you think.
Foods that are giving you stomach problems should be avoided as you will not be absorbing them correctly and they can cause health problems eventually (food sensitivities can cause various digestive disorders).
This is especially important if you are eating large amounts.What if you have food allergies against whey, egg white, oats and chicken? That’s 90% of your diet down the drain.
7) Bacteria are the bosses -charm the pants of the good bacteria. Gut bacteria can be changed with lifestyle changes (stress and food), drugs and supplements.
- Have good bacteria friendly diet (being eastern European helps) helps to take in the right amount of good fats and eat more fermented foods.
- Take prebiotic and or probiotic supplements. Prebiotics are fuel for good bacteria, while probiotics are the good bacteria itself (acidophilus and bifidobacteria supplements).
8) Learn how to manage stress (sort your emotions out and learn how to relax). We’re not built to handle stress for prolonged periods of time- It’s a complicated area that needs extra snooping around.
- The stress hormone cortisol can affect the stomach by messing with the pH levels and causing hypothyroidism (one of the Achlorhydrias causes).
- Stress can affect your gut health by lowering your metabolism, messing with your adrenal glands, causing gastric ulcers, increase inflammation and can cause a decrease in HCL secretion.
Infection is the main cause of increase in intestinal permeability, but stress may also be a factor (Camilleri et al., 2012).
- According to Camilleri et al, the mechanism of increased permeability is via mast cells which stimulate T-lymphycytes to produce inflammatory cytokines (including interferon-C) leading to an increase in colonic permeability.
- Studies in humans have demonstrated that acute pain stress activates mast cells resulting in an increase in histamine, tryptase and prostaglandin D2 release.
- Chronic physiological stress might well account for the increased mast cells recorded in the colon of IBS patients who are often anxious and depressed.
- Both GI infection and chronic stress in susceptible individuals appears to lower epithelial cell function.
9) Fibre can help especially when on a ketogenic diet.
10) Increase your antioxidant intake to help fight free radicals and inflammation – from food or supplements (vitamin e, alpha lipoic acid, NAC, the amino acid cysteine which is coincidentally found in whey protein etc.).
11) Glutamine supplementation can restore intestinal permeability and decreases bacterial translocation. Glutamine deficiencies can cause epithelial cell permeability increase (Camilleri et al., 2012).
This article isn’t supposed to strike fear into your hearts and make you go buy all of the supplements listed.
It’s supposed to 1) show how complicated the human body really is 2) be educational and 3) hopefully to teach you how to become a mad scientist.
Drop me a comment below and tell me what you think or tell me how much I suck (I’m sure I’ve missed or misunderstood something).References used (Click here to expand)
Most websites included throughout.
You Are What You Absorb by John Meadows (an awesome piece of work and a lot of the recommendations are from there).
You Don’t Know How to Digest by Nate Green and Robert Yang.
Various lecture notes.
The Gastrointestinal System at a Glance Book by Satish Keshav, Director, Centre for Gastroenterology, Royal Free Hospital and University College Medical School, London.
P. Hunter (2012). The changing hypothesis of the gut. Science & Society. EMBO reports (2012) 13, 498–500; published online 15 May 2012; doi:10.1038/embor.2012.68
M. CAMILLERI, K. MADSEN, R. SPILLER, B. G.VAN MEERVELD & G. N.VERNE (2012). Intestinal barrier function in health and gastrointestinal disease. Neurogastroenterol Motil (2012) 24, 503–512 doi: 10.1111/j.1365-2982.2012.01921.x
Elizabeth K. Costello, Keaton Stagaman, Les Dethlefsen, Brendan J. M. Bohannan, David A. Relman (2012). The Application of Ecological Theory Toward an Understanding of the Human Microbiome. Science 336, 1255 (2012); DOI: 10.1126/science.1224203.
“Stupid garbage compactor …” Photo by JD Hancock.
Image Intestinal epithelial cells regulate immune-cell function by David Artis.
Toilet timeline image .
Skinny image by Jon Bel.
Stress photo by William Brawley.
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