The Difference Between Fat-Soluble and Water-Soluble Vitamins
The Difference Between Fat-Soluble and Water-Soluble Vitamins

Science

The Difference Between Fat-Soluble and Water-Soluble Vitamins

3 min read

Essential Takeaways

  • Not all vitamins are created equal: Beyond supporting different functions in the body, nutrients can typically be categorized as either fat-soluble or water-soluble.
  • So, what’s the difference? It really comes down to the way fat-soluble and water-soluble vitamins are metabolized in the body.

We probably don’t need to remind you that multivitamins can be a great way to help fill gaps in your diet and support different functions in the body. But for many, how those vitamins are absorbed and metabolized is a bit of a question mark.

The way your body absorbs different vitamins plays a large role in both efficacy and safety, which is why it can be really helpful to understand the difference between water-soluble and fat-soluble vitamins.

So what, exactly, is the difference? Let’s talk about how water-soluble vitamins absorb into the body compared with fat-soluble vitamins, which vitamins are water-soluble vs. fat-soluble, and what’s worth knowing about each category.

Water-soluble vitamins

As the name suggests, a water-soluble vitamin is one that dissolves in water—and as a result, is easily absorbed into the tissues of the body and metabolized more quickly than fat-soluble vitamins.

The majority of vitamins, including the B vitamin complex and Vitamin C, are water-soluble (1):

  • Vitamin B1 (thiamine)
  • Vitamin B2 (riboflavin)
  • Vitamin B3 (niacin)
  • Vitamin B5 (pantothenic acid)
  • Vitamin B6
  • Vitamin B7 (biotin)
  • Vitamin B9 (folate)
  • Vitamin B12 (cobalamin)
  • Vitamin C

Any excess of water-soluble vitamins, like the Vitamin B complex or Vitamin C, are excreted through the urination process. Many B vitamins and Vitamin C can be found in vegetables (like leafy greens and other green vegetables) and fruits (like citrus fruits).

Fat-soluble vitamins

Fat-soluble vitamins dissolve in—you guessed it—fat. These vitamins are absorbed by fat globules within the body and then carried throughout the bloodstream. There are four fat-soluble vitamins, which include:

Fat-soluble vitamins are found in high-fat food sources like egg yolks, liver, beef, fatty fish, and dairy products. Unlike water-soluble vitamins, any excess of fat-soluble vitamins don’t immediately leave the body. Instead, they’re stored in the liver or fatty tissue for later use (2).

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Considerations for water-soluble vitamins vs. fat-soluble vitamins

The main difference between water-soluble vitamins and fat-soluble vitamins is how they’re absorbed into and act within the body—but there are other considerations to keep in mind for all vitamin types.

One major benefit to water-soluble vitamins? The chance they’ll build up within the body is highly unlikely, even at large amounts; any excess exits the body when you pee. This also means that because water-soluble vitamins are either used or excreted so quickly, if you want to reap the health rewards associated with water-soluble vitamins, you’ll need to consistently get them into your system through nutrient-dense foods and supplements that help fill the gaps in your diet.

Fat-soluble vitamins, on the other hand, don’t immediately leave the body—and, instead, are stored in the liver and fatty tissue. Because these vitamins are stored in the body, excess is more likely—and that’s not necessarily a good thing. That’s why it’s important to stick within the recommended guidelines.

Essential for Women

Your body needs both water-soluble vitamins and fat-soluble vitamins to function at its highest level. Ritual’s Essential for Women multivitamin features both water and fat-soluble vitamins to help fill the gaps in your diet and support your body’s nutrient levels.

References:

  1. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. (1998). doi: 10.17226/6015
  2. Dietary Reference Intakes for Calcium and Vitamin D. (2011). doi: 10.17226/13050

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