Water vs. Fat-Soluble Vitamins

There are 13 vitamins in all, and you need every single one, no exceptions. Your body must have them in small amounts for normal growth, metabolism (creating energy in your cells), and health. You need vitamins to make enzymes and hormones — important substances your body uses to make all the chemical reactions you need to live. You must get your vitamins from your food or from supplements — your body can’t make them.

What are Water-Soluble Vitamins?

Water-soluble vitamins include vitamin C and all eight B-vitamins (B1, B2, B3, B5, B6, B7, B9, and B12), and they dissolve in water.

Our body is about 70% water, so the water-soluble vitamins absorb directly into our blood and circulate freely into the water-filled compartments of the body.

Our kidney’s remove excess water-soluble vitamins, which is why they’re needed in small, frequent doses. Unless you take truly massive doses of water-soluble vitamins, it’s difficult to overdose; however, the excess does put extra strain on your kidneys and makes for some expensive urine. 

What are Fat-Soluble Vitamins?

The fat-soluble vitamins include Vitamins A, E, D, and K. They dissolve in fat but not water and typically require protein carriers for transport through the body. They are primarily stored in the cells associated with fat and the liver. Because these vitamins are stored for longer periods of time, you don’t need a supply of them every day, and getting too much may cause problems.

As with the water-soluble vitamins, the function of one fat-soluble vitamin often depends on the presence of another. For example, vitamin E protects vitamin A from oxidation. In vitamin E deficiency, vitamin A absorption and storage are impaired.

Also, three of the four fat-soluble vitamins (A, D, and K), play important roles in bone remodeling and work together to promote bone health.

Fat-soluble vitamins also interact with minerals; an example is vitamin D and calcium (a mineral).

Take Vitamins With or Without Food?

Water-soluble vitamins (B-vitamins and vitamin C) can supposedly be taken on an empty stomach, but I’ve found this can lead to heartburn or an upset stomach. If that happens, taking the vitamins with food may alleviate the discomfort. Also, take any B-vitamins before 3pm or they may interfere with your ability to fall asleep at night. 

Take your fat-soluble vitamins (Vitamins A, D, E, and K) with dietary fat. These vitamins require fat for optimal absorbtion and to be transported throughout the body.

Capsules vs Tablets

Some advantages of capsules: Sealed hard gelatin caps can be good oxygen barriers, which provides protection for sensitive vitamins; Shell normally breaks down/opens in 4 minutes; Reduced gastrointestinal irritation; Odorless, tasteless, easy to swallow; Oil and fat-soluble nutrient delivery 

Some disadvantages of capsules: Can be susceptible to moisture; Ingredients can interact with capsule shell; Costly; Capsule or lubricant allergies/sensitivities are possible; "junky" filler ingredients in the capsule; artificially colored capsules

Some advantages of tablets: Notching possible for dose splitting; Low cost coatings for enteric delivery; Dissolution control for quick, delayed, or extended release

Some disadvantages of tablets: Excessive compaction and poor ability to dissolve; Granulation technique can add heat/moisture to viable components; Customer concerns/self-testing of tablets ability to dissolve; Coating sensitivities 


If you're interested in a plant-based vitamin and mineral supplement, Essential 21 is made from 100% organic ingredients. 


In Health and Happiness,

Kelly Harrington, MS, RDN

Registered Dietitian Nutritionist for Healthy Goods

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