Nutrient Absorption & Metabolism
A Primer On Nutrient Absorption & Metabolism
The human body is well-equipped to break the foods we each into tiny particles and absorb them into the bloodstream, where they can be used to drive growth and cell metabolism.
But sometimes, this process isn’t as efficient as we’d like, and the supplements we’re spending our money on aren’t being absorbed efficiently.
This guide will cover how nutrients and supplements are broken down, absorbed, and metabolised by the body. We’ll offer some tips on how you can improve absorption to get the most out of your supplements.
An Overview On Digestion & Absorption: How Does It Work?
There are a wide variety of different types of compounds we take into the body — the majority of these compounds are too big to be absorbed. They must first be broken down into smaller parts.
In order to disassemble these compounds into smaller pieces, we need a diverse set of techniques to be able to break fats, proteins, and carbohydrates down. The body uses enzymes, acids, and beneficial bacteria to achieve this.
An enzyme that can break down fats may do nothing to break down a protein — which has a completely different shape and structure. We need a different enzyme specifically made for proteins to chop it into smaller bits for absorption.
Digestion and absorption require multiple different stages to thoroughly homogenise the food and supplements we each so we can absorb them. Here’s an overview of the entire process:
- Chewing breaks large pieces of food or nutrients into smaller pieces. This increases the surface area of the meal to help break it down at a faster rate.
- An enzyme in saliva called amylase gets to work immediately to convert large, complex carbohydrates into simple, absorbable sugars.
- Once in the stomach, concentrated hydrochloric acid destroys the bonds in various fats, carbohydrates, and proteins, causing them to break apart.
- In the small intestine, other enzymes secreted by the liver and pancreas target fats, proteins, and carbohydrates to chop them into their simplest forms.
There Are Two Pathways For Nutrient Absorption
There are two separate pathways when it comes to absorption of food and supplements — there’s a path for fat-soluble compounds and a path for water-soluble compounds.
1. Water-Soluble Nutrient Absorption
Water-soluble nutrients are generally the easiest to absorb. The blood is water-based, so these nutrients can pass directly from the digestive tract into the bloodstream. They’re absorbed through tiny protruding cells in the intestinal wall called the microvilli. Nutrients then travel through the villi and into a section of the bloodstream directly in front of the liver.
This means that all water-soluble nutrients and supplements are forced through the liver before heading to the rest of the body. The liver does a quick “once-over” to metabolise as much as it can. This is referred to as “first-pass metabolism.” Once everything leaves the liver, it enters systemic circulation where it’s spread throughout the rest of the body via the bloodstream.
2. Fat-Soluble Nutrient Absorption
Fat-soluble nutrients, like vitamins A, D, E, and K, and supplements like CBD or Boswellia require an extra step before they can be absorbed. This is because this type of compound won’t naturally dissolve into the blood. It needs to first enter a network consisting of a fatty substance called lymph — which flows throughout the body in parallel to the bloodstream. This system is called the lymphatic system. Unlike the bloodstream, lymph doesn’t have a pump to move it around the body. Instead, it moves through a series of one-way valves activated by the muscles as you move around during the day.
After entering the lymphatic system, nutrients travel up the network of lymph fluid and are gradually deposited into the bloodstream in a section of the aorta (the primary arteries feeding into the heart). These fat-soluble substances are able to dissolve in blood at this point by binding to transporter proteins.
How to Boost Nutrient Absorption
Everybody absorbs nutrients differently — some do a much better job than others.
Factors like your age, weight, digestive health status, microbiome, and genetics all play a factor in how we absorb certain nutrients.
If we’re not absorbing nutrients effectively, we may only be getting a small fraction of the benefits of a certain supplement. For example, if we’re only absorbing 20% of the magnesium we consume, we may not be getting the benefits we think we’re getting from the standard dose. Our options are to either take more magnesium with each dose or taking steps to optimise the amount we do absorb.
Here are five quick tips to improving your ability to absorb nutrients and supplements:
1. Learn What Nutrients to Pair Together
Some nutrient combinations can increase absorption — others compete with each other and reduce absorption. It’s wise to understand what nutrients should and shouldn’t be taken together.
Taking supplements apart involves waiting about 2 hours between doses to give them time to absorb and avoid competing with each other.
Here’s a quick list of health supplements that pair well together to boost absorption:
- Vitamin C & iron
- Turmeric & ginger or black pepper
- Vitamin C & calcium
- Fat-soluble vitamins (E, D, & K) & a source of fat (oils or butter)
- Vitamin D & vitamin K
2. Use Probiotics
Our microbiome plays a pivotal role in our ability to digest nutrients. They improve absorption by breaking compounds down into smaller parts and maintaining the health of the intestinal wall. A healthy microbiome also helps resist infection by other microorganisms that can damage the microbial and make it even harder to absorb food and nutrients.
Probiotics work through a similar philosophy to overseeding your front lawn. It increases the amount of bacteria that enter the gut, some of which take root and form new colonies of helpful bacteria.
It’s a good idea to take probiotics around the same time each day to keep the microbiome strong and healthy so it can do its part in optimising our absorption.
3. Avoid Drinking Tea With Your Supplements
Tea has a long list of health benefits — but it’s not all good.
A group of compounds in green, black, and oolong tea called catechins offer powerful antioxidant support, but they also tend to bind and neutralise nutrients. They’re also highly astringent, which means they cause the cells in the digestive tract to huddle together — making it more difficult for food and nutrients to pass through them.
We strongly recommend drinking tea, but just remember to wait about 30 to 60 minutes after you’ve taken your supplements before you have your next cup.
4. Keep Stress Levels To A Minimum
High-stress levels are a common cause of poor digestion. The stress response causes several core changes to the body. One of these changes is a complete shut-down of digestion. The idea is that we don’t need digestion to fight or run away from danger, so it’s shut down to conserve the energy for our muscles and brain instead.
Stress significantly reduces the amount of nutrients we absorb — which is why it’s important that we find ways to manage our stress levels — especially when it comes time to eat.
Try and avoid eating on the run or eating while you work. Take the time to sit, relax, and enjoy your meal. You’re going to get a lot more from it as a result. The same goes for supplements. Try and take your supplements at a point in the day where your stress levels are at their lowest. For most people, this is the first thing in the morning when you wake up.
5. Drink Warm Water
We need water to digest the foods and supplements we eat. Nutrients can only pass through the microvilli and into the bloodstream by being carried by water. Without it, nutrients just sit in the gut unabsorbed. If they sit for too long, harmful bacteria tend to feast on it instead, which can cause problems with gas, bloating, and inflammation in the digestive tract.
It’s best to opt for lukewarm filtered water to help with absorption. Iced water can actually have the opposite effect, slowing down digestive inertia and making it harder for the body to absorb the supplements we consume.