How We Digest Vitamins and Minerals, and 4 Factors That Can Inhibit Absorption

We tend to lump the words "vitamins and minerals" together because these compounds, enzymes and/or antioxidants offer many health benefits together.

Yet the way these vital nutrients are digested and absorbed into the body isn't entirely the same — and some factors could stand in their way.

"Vitamins are organic substances made by plants or animals," Katherine Brooking, RD, co-founder of Appetite For Health, tells LIVESTRONG.com.

In total, there are 13 essential vitamins that are necessary in order for proper cell function, growth and development, per the U.S. National Library of Medicine.

All vitamins fall into one of two categories: fat-soluble and water-soluble.

"The fat-soluble vitamins — A, D, E and K — dissolve in fat and can be stored in your body," Brooking says. The water-soluble vitamins — C and the B-complex vitamins (such as vitamins B6, B12, biotin, niacin, riboflavin, thiamin, pantothenic acid and folate) — need to dissolve in water before the body can properly absorb them. "And because of this, your body cannot store these vitamins."

"Any vitamin C or B that your body doesn't use as it passes through your system is lost (mostly when you pee). Therefore, you need a fresh supply of water-soluble vitamins every day."

On the other hand, Brooking explains that minerals are inorganic elements that come from the soil and water and are absorbed by plants or eaten by animals.

Minerals maintain their chemical structure, while vitamins can be broken down by heat, air or acid, according to HelpGuide, a non-profit organization that collaborates with Harvard Medical School.

Similar to vitamins, minerals are also divided into two categories: macrominerals (sometimes referred to as major minerals) and trace minerals.

Your body needs larger amounts of the macrominerals (which include calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur) to grow and stay healthy, Brooking says. Yet the body only requires a small amount of trace minerals (iron, manganese, copper, iodine, zinc, cobalt, fluoride and selenium).

"Water-soluble vitamins are packed into the watery portions of the foods you eat," Brooking says. As food is broken down during digestion — or as a supplement dissolves as it makes its way through your system — these vitamins are absorbed directly into the bloodstream.

"Since much of your body consists of water, many of the water-soluble vitamins circulate easily within the body," she says. And the kidneys continuously regulate levels of water-soluble vitamins, shunting excesses out of the body during urination.

But, once fat-soluble vitamins are absorbed, they enter the lymph channels and then head into the bloodstream. In fact, the majority of fat-soluble vitamins must latch onto a protein in order to travel through the body, Brooking adds.

"Generally speaking, it's fair to say that both macrominerals and trace minerals are absorbed in the small intestine," Brooking says.

Yet the mechanism in which certain minerals absorb can differ. For example, calcium goes through two processes before it's absorbed via the intestinal lumen (an opening within the intestine) while phosphorous is mostly absorbed in the upper small intestine — and both minerals rely on vitamin D for absorption, according to Colorado State University.

Even if you're eating a well-balanced diet and taking vitamin and mineral supplements on a daily basis, certain factors may affect your body's ability in absorbing essential nutrients.

"As we age, our bodies become less efficient at extracting and absorbing nutrients from the foods you eat and the supplements you take," explains Brooking. "Eating more nutrient-dense foods, such as richly colored fruits and vegetables, can help."

Certain medications can bind with nutrients and inhibit their absorption, Brooking says. For example, antibiotics can hinder the production of vitamin K and B-complex vitamins, which in turn can eliminate the "good" gut bacteria, according to a May 2019 article in the journal ​ACTA Scientific Nutritional Health​.

Brooking explains that alcohol may encourage the swift breakdown of pills and capsules before they reach the small intestine where absorption occurs.

"It can also interfere with normal digestion by damaging cells in the stomach and intestine, as well as interfere with the release of important digestive enzymes."

"The constant stresses of daily life can take a toll on your body, depleting nutrient stores and altering your body's digestive efficiency," says Brooking.

Numerous physiological changes can occur when the body is under chronic stress, including a depletion of vitamins and an impaired immune system, per a June 2016 study in the ​Journal of Nutrition & Food Sciences​.