Why are fat-soluble vitamins important?
You might be taking your daily multivitamins, or perhaps created your own stack of supplements taken on a daily basis? Then the chances are, that fat-soluble vitamins are in there. But do you even know what are the upper limits beyond which you should not go? It is easy to pop a few tablets of cod oil and vitamin A without actually knowing how much you take…
Fat-soluble vitamins A, D, E, and K are important for our health, helping with our immune system, vision, bone strength, and skin appearance. Unlike water-soluble vitamins that our body keeps for up to two days, these vitamins are stored in our body’s fat and liver so they can be used when needed. This storage helps them support essential body functions over time, making them essential for overall health.
Ensuring we get the right amount of fat-soluble vitamins to maximize the health benefits can be quite a balancing game. That’s why understanding how much we should consume as a maximum and from where we can get them will help us strike this fine balance. In this article we will explore fat-soluble vitamins, their benefits, and the best food sources to help you get your daily dose. Get ready to improve your health, one vitamin at a time!
How to best absorb fat-soluble vitamins?
As the name of this article indicates, our body can properly absorb fat-soluble vitamins in presence of fat. Hence it is important to include fat sources in our diet when we eat our veggies for instance. This can be done by adding a tablespoon of olive oil to our salad, get a piece of avocado or a handful of nuts or seeds, eat an egg or cheese etc. on a regular basis.
Vitamin A (Carotenoids and Retinoids)
What is vitamin A?
Vitamin A is a group name for various compounds also known as carotenoids and retinoids. These are important in maintaining a healthy vision. Vitamin A also aids formation of tear fluid and light sensitive cells in our eyes. Additionally similar to vitamin D, it helps maintaining our immunity which helps us decrease our chances of infection. Not only that, it also aids cell growth and division. Visually this can be seen in hair growth and maintaining healthy skin. For this reason retinoids are a common part of various cosmetic products.
Where can we get vitamin A from?
Vitamin A can be found in animal products such as liver, eggs or butter in the form of retinol and retinyl esters. Another form are carotenoids. Conversion of plant sources of carotenoids into vitamin A is more complex. Why? Unfortunately not all carotenoids (plant pigments) can convert to vitamin A, actually only a small proportion have this ability. Plant sources of beta-carotene that converts to vitamin A in our liver are carrots, red bell peppers, kale or spinach among others. As plant sources are harder to convert to vitamin A so vegans are more likely to be deficient in vitamin A, even though deficiency is still rare provided we follow a balanced diet.
How much of vitamin A should we have daily?
Unlike beta-carotene, which is not known to be toxic even in larger amounts, preformed Vitamin A if taken in high amounts via supplements can become toxic. As the maximum limit for an adult male and female (Tolerable Upper Intake Levels (ULs) for Preformed Vitamin A) would be considered daily dose of 3000 mcg in form of both food sources and supplements. (1)
Did you know?
Cod liver oil contains a significant amount of vitamin A so be careful with how much you get if you also take vitamin A additionally in form of any other supplement. Vitamin A present in various creams does not get in our bloodstream so does not need to be included in the above daily amounts.
Vitamin D
What is vitamin D?
Vitamin D keeps our bones strong. This is done by aiding the regulation and absorption of calcium and phosphorus. A lack of it causes our bones to soften. It also helps to regulate and strengthen our immunity system and ensures we are less likely to suffer from some autoimmune diseases.
You have probably heard of vitamin D referred to as a sunshine vitamin. This is because our body produces it when we expose our skin to the sun. Nevertheless, as we spend a lot of time indoors or cover our body in clothes and our face with sunscreen, many of us become vitamin D deficient, especially in winter. Vitamin D deficiency is one of the most common vitamin deficiencies in the Western world. This is even more likely the case for people with a milk allergy or lactose intolerance, vegetarians, and vegans. (2)
There have been various trials testing the impact of vitamin D supplementation on the prevention of cancer, cardiovascular diseases, and type 2 diabetes without reaching a firm conclusion that supplementing vitamin D would improve these. (2)
Where can we get vitamin D from?
Except for sun exposure, we can get vitamin D from our diet. There are two main forms of vitamin D. Vitamin D2 and D3.
Vitamin D2 is present in mushrooms and some fruits (oranges, kiwi, banana) and veggies (broccoli, spinach, sweet potato).
Vitamin D3 is present in animal sourced food such as eggs or fish oil. Additionally sunlight also aids creation of vitamin D3.
How much of vitamin D should we have daily?
Vitamin D can be toxic in high amounts. Maximum daily Tolerable Upper Intake Levels (ULs) for Vitamin D for an adult male and female from all sources is 100 mcg (400O IU). High amounts could cause kidney and heart damage. (2)
Vitamin E
What is vitamin E?
Vitamin E is an antioxidant. It protects cells from premature aging which is caused by free radicals. This antioxidative process is aided by presence of vitamin C, vitamin B3 and selenium. Various studies examined potential impact of supplementing vitamin E and its effect on cardiovascular health and cancer with mixed results, but have proven positive impact in cases of macular degeneration. (3)
Where can we get vitamin E from?
Vitamin E is present in some vegetable oils (the most in wheat germ oil), seeds and nuts.
How much of vitamin E should we have daily?
Provided we follow a healthy diet, it is unlikely that we would be deficient in vitamin E. Taking too many supplements containing vitamin E could cause blood thinning and potentially fatal bleeding. The daily tolerable upper intake level (UL), in another words a maximum level that would not cause adverse effects, for Vitamin E should not exceed 1000 mg (natural and synthetic combined) for a adult male or female. (3)
Vitamin K
What is vitamin K?
Vitamin K is important for us as it prevents from excessive bleeding. This is because it aids creating proteins that are necessary for blood clotting.
It can naturally be found in two forms. As vitamin K1 (phylloquinone) in various leafy greens such as spinach, kale, Brussel sprouts, cabbage, lettuce or parsley. Or we can get it naturally in smaller amounts from animal based foods such as eggs or cheese in the form of vitamin K2 (menaquinone). Vitamin K is present in good amounts in soybeans (also in their fermented form called Natto) Additionally K2 is produced inside of our body by our gut bacteria. Vitamin K is also available in its synthetic form, such as K3, K4 and K5.
How much of vitamin K should we have daily?
It is stored in our body for a limited time only, approx. one week so even though it is quite rare to be vitamin K deficient, we want to ensure that we eat foods rich in vitamin K on a regular basis. We need to pay extra attention to our diet in relation to vitamin K when we use antibiotics as they are known to reduce our gut bacteria that is responsible for vitamin K production.
How much of vitamin K should we have daily?
Vitamin K does not have any known toxicity, neither is there any scientifically proven recommended daily amount of this vitamin. Unlike in case of other fat soluble vitamins where we need to ensure we do not overdose on those if we take them in the form of supplement additionally to our food, this is not the case of vitamin K.
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Resources:
(1) Vitamin A, National Institutes of Health, U.S. Department of Health and Services downloaded from web 08/01/2025, https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/, Vitamin A and Carotenoids – Health Professional Fact Sheet
(2) Vitamin D, National Institutes of Health, U.S. Department of Health and Services downloaded from web 08/01/2025, https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/, Vitamin D – Health Professional Fact Sheet
(3) Vitamin E, National Institutes of Health, U.S. Department of Health and Services, downloaded from web 08/01/2025, https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/ Vitamin E – Health Professional Fact Sheet
