What Are Fat-Soluble Vitamins?

What Are Fat-Soluble Vitamins?

Vitamins are classified into two main groups – fat-soluble and water-soluble. Understanding the difference between the two is very important as each vitamin acts differently within the body. 


Understanding Fat-Soluble Vitamins: Back To Basics

Fat-soluble vitamins are vitamins A, D, E and K. As the name suggests, fat-soluble vitamins dissolve in fats and oils. Unlike water-soluble vitamins that need regular replacement, fat-soluble vitamins are stored in our bodies and absorbed as and when we need them. They are stored in the liver and fat tissue for extended periods of time, with some being stored for at least six months!


A Built-In Storage System

While the body’s ability to store fat-soluble vitamins offers protection against deficiency, it also presents potential hazards. Storing these vitamins for as and when we need them can bring a risk of stores building up to toxic levels. This is very unlikely in a healthy and well-balanced diet, but if taking supplements or ‘doubling up’ it can sometimes mean overconsumption – for example if you are taking a vitamin A supplement but don’t realise that your multivitamin already contains it!


Navigating Optimal Vitamin Levels

Whilst overconsumption is possible, vitamin deficiencies tend to be more common. For example a vitamin D deficiency, affecting a significant portion of the population, particularly in regions with limited sunlight exposure. 

Factors such as low-fat intake or impaired fat absorption can contribute to fat-soluble vitamin deficiencies, highlighting the importance of dietary fat in vitamin absorption. Fortunately, fat-soluble vitamins are abundant in a variety of foods, including animal fats, vegetable oils, dairy products, liver and oily fish. It’s also important to highlight that, unlike water-soluble vitamins, fat-soluble vitamins are not lost when foods that contain them are cooked.

There are 4 fat-soluble vitamins – vitamin A, D, E and K.


Vitamin A

Vitamin A is made up of a group of fat-soluble compounds called retinoids, with the most common form being retinol. Vitamin A has a variety of vital functions in the body including: supporting our immune system, vision and skin.

Retinol is only found in animal products such as fish liver oil, beef liver, butter and egg yolks. However, beta-carotene can be derived from plant-based foods like carrots, kale and spinach, which is then converted into retinol (vitamin A) in the body.

Vitamin D

Vitamin D plays a crucial role in maintaining our overall health and biological processes. Vitamin D has a variety of vital functions in the body including supporting our immune system and helping to keep our bones, teeth and muscles healthy, by aiding calcium absorption. 

It’s found in certain foods such as fatty fish (salmon, mackerel, sardines), and as mentioned above, vitamin D deficiency is fairly common. You can increase the amount of vitamin D you are getting by eating foods rich in vitamin D, taking a supplement (especially in the winter months) and making sure you get outside. 

Vitamin E 

Vitamin E is a group of eight fat-soluble compounds that contribute to cell production and help maintain healthy skin and eyes. Vitamin E is found in vegetable oils, seeds and nuts with particularly high amounts found in sunflower seeds, almonds and hazelnuts.

Vitamin K

Vitamin K is made up of fat-soluble compounds and can be naturally produced by the bacteria in the intestines. It plays significantly important roles in blood-clotting and bone health.

There are two types of vitamin K in the diet: vitamin K1 and vitamin K2. Vitamin K1 is mainly found in plant foods, particularly green leafy vegetables like chard, kale, spinach and K2 is found in certain animal foods in small amounts like beef liver, chicken, cheese and egg yolk, as well as fermented foods.


The Role of Food in Maximising Vitamin Absorption

To optimise the absorption of fat-soluble vitamins, it’s essential to consume them alongside dietary fat, such as avocado, olive oil, nuts, seeds or oily fish like salmon. Consuming foods and nutrients that contain adequate amounts of fat enhances their absorption and utilisation by the body.



Fat-soluble vitamins play a crucial role in maintaining our overall health and well-being, from supporting immune function to promoting bone health and beyond. While their storage within the body provides a safeguard against deficiency, it’s essential to maintain a balanced approach to vitamin intake to avoid overconsumption. By incorporating nutrient-rich foods into your diet, you can harness the power of these essential vitamins to support your journey towards optimal health and nutrition. 


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