Digestion Under Stress

I’ve talked a lot in my book and blog about the effects of stress on heart disease risk, sleep and obesity, but I want to focus in this post about the effects of stress on digestion (how well our body breaks down food) and nutrient absorption (how well our body absorbs nutrients from inside the intestine, so it’s delivered to our body’s cells).  Stress may be one of the most important barriers between the nutrients you are eating and the nutrients your body is actually receiving.  As a quick refresher, the sympathetic nervous system (aka “flight or fight”) is the branch of our nervous system that mediates the stress response, while the parasympathetic system mediates the relaxation response (see diagram below).  The goal of stress reduction is to try to activate our parasympathetic system as often as we can.

What happens to a digestive system under stress?  If the ground started shaking from a massive earthquake and you needed to run for shelter within seconds or move your loved ones to safety, the last thing you would have time for is a trip to the bathroom.  Your sympathetic nervous system instantly reduces blood flow to your digestive organs, it inhibits the release of digestive enzymes, it causes your intestines to literally become paralyzed so food is no longer in motion and it closes down your anal sphincter (muscle responsible for opening and closing the anus) like a trap door to prevent a bowel movement.  This is a brilliant adaptation that reroutes your blood flow and metabolism to prioritize mental alertness and motion so you can fight, flee, and protect, rather than digest and eliminate (waste).  However, what does it mean when we eat in the midst of our typical, chronically stressed out lives?  Let’s list off the short-term adaptations I just discussed and understand how they become maladaptive under chronic stress:

  • Reduced blood flow to the intestines: Impairs nutrient absorption.  Over time reduced blood flow to the intestines may damage the lining of the gut and cause gut inflammation (see below).
  • Reduced secretion of gastric acid and digestive enzymes: Without sufficient stomach acid and digestive enzymes, you cannot adequately break down (digest) food, so as a result you get large undigested food fragments which impairs nutrient absorption, causes overgrowth of unwanted bacteria and can manifest with symptoms such as bloating, excess gas and acid reflux.
  • Reduced peristalsis:  Peristalsis is the normal rhythmic contraction of the esophagus (swallowing tube) and intestines that moves food through the digestive tract.  Stress disrupts this smooth rhythm, causing food to get stuck in various segments, leading to conditions like acid reflux, constipation, and  irritable bowel
  • Tightened sphincter: I explained how your anal sphincter is like a muscular trap door and during chronic stress the trap door stays constricted.  This means during bowel movements you are straining to get the stool from your rectum into the toilet, across a closed valve (your tight anal sphincter) and this excessive force and pressure swells up the surrounding blood vessels causing hemorrhoids (aka piles) and painful anal fissures
  • Inflammation:  80% of your immune system resides in your gut.  When you are sending undigested food fragments into your intestines and colon and feeding unhealthy bacteria, this acts as a major stimulus to your immune system to trigger inflammation.  In addition, the stress hormone cortisol actually opens up the gaps between cells in your intestinal wall, causing unwanted toxins, bacteria and food fragments to seep outside the gut and signal rampant inflammation. I’ve highlighted in several prior posts how this inflammation is implicated in virtually every major chronic illness from autoimmune diseases and diabetes to cancer and premature aging.

See the parasympathetic/sympathetic diagram below and I circled in red the effects on the digestive system under sympathetic (stress) activation.

I used to have a problem with food getting stuck in my throat. I blamed it on a narrow esophagus, but now understand that my overactive sympathetic system prevented the normal peristalsis that would allow food to rhythmically pass from my esophagus (swallowing tube) into my stomach.   Instead, my esophagus would be knotted up from me shoving food down my throat in between patients.  I had a few embarrassing episodes at meetings where I had severe choking episodes where I had to step outside the room.  Yes, you can add one more way that stress kills…by causing you to choke to death!

How Should You Eat?

Before You Eat: Whether you are religious or not, I think the act of praying or giving thanks before a meal makes perfect sense.  I try to remind myself to take 7 deep and slow breaths before I eat to calm down my nervous system.  If you want to be even more technical, you can check your pulse to see if you are at or closer to your resting pulse rate.  If you want to be high-tech, use your smartphone to check your pulse.   There are a growing list of free heart rate Apps that use your smartphone flash to monitor your pulse.  I use Instant Heart Rate by Azumio.

Chew Your Food and Slow Down:  You must chew your food sufficiently to activate enzymes in your mouth (salivary amylase) to start the process of digestion and also to allow adequate time for your stomach to release gastric acid to further digest food.  Undigested food particles in the stomach can cause bacterial overgrowth, leading to bloating and acid reflux.  Just for fun, see how many times you typically chew your food before swallowing.  Try to double the number of chews and aim for 20-30 if you can.  You might also be familiar with the fact that it takes an average of 20 minutes after a meal for satiety (fullness) to be felt.  Multiple studies have shown that eating slower (chewing more) leads to less food intake at a given meal and keeps you full longer after that meal.

Don’t Dine With Devices:  We often think of stress as being a negative emotional reaction such as anger or fear.  Many of us think checking our personal e-mail, facebook page, or twitter feed is a way of reducing stress in which case it should improve digestion, right? WRONG!  Pay attention to how your mind races and how you breathe when you are frantically scrolling down your e-mail list.  You might perceive this as a break from work or the kids, but your brain perceives this as stress and that will assuredly impair digestion and nutrient absorption.

Dining With Friends, Family and Co-workers: For the most part I prefer to dine with people over devices, but if you have a co-worker that only complains about work and raises your own stress levels, then like secondhand smoke he or she might be a hazard to your health.  We all need to vent, but try to bring up some topics other than work or whatever your stress cues are, and try to add a humorous spin so there is as much laughing as complaining during social meals.   It’s neat to think that by making others laugh and relax during a meal, you are actually optimizing their digestion.

Drink Water Between Meals:  It’s a common habit to drink water during meals, but water intake during eating can dilute your stomach acid and make it less effective at breaking down your food.  Recall large, undigested food fragments can lead to bacterial overgrowth in your stomach or in your intestine causing bloating, gas and shifts to less healthy bacteria in your colon.  Drinking water about 2 hours after eating is a good rule of thumb.

Avoid Meals “On the Run” When You Can 

Breakfast “on the run” is very common.  Many of my patients blend up a quick smoothie which they proceed to gulp down on their stressful commute to work.  Think about that for a second.  Your blender already partially digested the food for you and now you are quickly drinking it down under stress.  How much of the nutrients are you actually absorbing as a result of this?  It’s better to wake up a little earlier and give yourself time to eat breakfast if you are hungry.  If you’re not hungry, then don’t eat until you are and especially until you have a break when you can try to follow some of the principles we discussed.  Overall I prefer chewing my food over drinking it.  However, I do juice intermittently and like to leave some pulpy chunks of green veggies like kale that I can chew to stimulate my digestive enzymes.  I also drink it in small sips…..SLOWLY.  For lunches at work if I can’t dine with a friend or co-worker, I often turn my computer monitor off, silence my phone and flip it over and then either eat outside to fortify my meal with some  solar vitamin D, or turn my chair towards a window, away from any addictive screens. Sometimes I plug in my headphones and listen to some relaxing music while eating if I’m really on edge.

How About Our Kids?

Are you rushing your kids through their breakfast or throwing them a waffle like a frisbee while they sprint to catch the school bus?  Are their homework and books sprawled across the dinner table while they mindlessly consume whatever you put on their plate?  Or are they constantly checking WhatsApp, Instagram or some other social media platform during meals or snacks?  Their growing bodies need to extract every ounce of nutrient from their foods to allow optimal physical and mental function and development.  I know family life is busy, but please try to plan as many family meals at the table as possible.  Studies repeatedly show that family meals encourage better health, lower body weight and stronger family bonds.

If you’re having trouble managing healthy family eating with a busy schedule, join me for a stellar free live program in the Bay Area where I’ll be joined by my pediatrician wife Dr.Shally, an awesome nutritionist, Prerna Uppal, and community partners like Whole Foods and others on 3/15.  Go here for details and spread the word.

Final Words

Over 800 million people on planet earth don’t have enough food to lead a healthy life.  We take our unlimited access to food quantity and diversity for granted.

Many of us are having organic produce and groceries delivered right to our doorstep.  If you don’t have time to meditate right now (read this for some inspiration), treat your meals as a time for mindful meditation.  Savor every bite (like the children above) and acknowledge each distinct flavor.  Be thankful that your stress is one of abundant e-mails and not insufficient food.  Sit, breathe, slow down, digest, absorb and appreciate, preferably with family and friends around you.  Life is too short.  Enjoy it one slow, nutrient dense bite at a time.