Hey hey readers! Welcome! In this month's blog post, I will go over fat soluble vitamins, including what they are, what they do in the body, food sources for them, and more. Vitamins are micronutrients that do not directly provide the body with energy; however, vitamins are incredibly important and essential for practically all metabolic reactions in the body. Fat-soluble vitamins are named such because they dissolve in fats and oils, and they must be absorbed along with fats in the diet. This means that if dietary fat is not present in the diet, it can impair the body's ability to absorb these essential micronutrients. In general, fat soluble vitamins play key roles in regulating blood glucose and insulin signaling, blood lipids, blood pressure, oxidative stress, and inflammation. Excess adipose tissue (i.e. fat) can sequester these vitamins, decreasing their availability for use.
Let's chat about each one of these vitamins - what do they do in the body, food sources that contain them, and what can happen if these vitamins are deficient in the body.
Vitamin A refers to a group of compounds referred to as "retinoids," where the most common retinoids are retinol (often used interchangeably with vitamin A), retinal, and retinoic acid. Vitamin A can also be made from beta-carotene and other carotenoids, which are pigments found in plants that given them their color. Carotenoids also function as antioxidants in the body. Vitamin A helps and assists with the following functions in the body: vision, bone growth, reproduction, growth of epithelium (i.e. the outer lining of skin, vessels), and fighting infections. Retinoic acid is often used a treatment for some skin conditions, such as acne, as it can help control protein production that contributes to acne. Severe deficiency in vitamin A can cause blindness; however, vitamin A is typically consumed in adequate quantities when following a balanced diet that includes some seafood, dairy, leafy veggies, and brightly colored fruits and veggies.
Sources of vitamin A include:
Liver and cod liver oil
Vitamin D helps and assists with immune function, bone formation, and calcium metabolism in the human body. Vitamin D can be manufactured in the body through the conversion of cholesterol to vitamin D by sunlight. There actually is a prevalence of vitamin D deficiency in the literature, where about 36% of otherwise healthy adults have inadequate levels of vitamin D, and about 56% of young athletes show vitamin D insufficiency. The risk of vitamin D deficiency tends to be increased in higher latitudes where there is less sun exposure. Thus, being exposed to some sunlight every day is actually really helpful for your body. Numerous meta-analyses have also linked low vitamin D levels to an increased risk of dying from any cause, cardiovascular disease, AND cancer. Furthermore, deficiency of vitamin D can contribute to osteoporosis, cardiovascular disease, type II diabetes, and rickets. While there are food sources that contain vitamin D, often dietary sources are insufficient to maintain adequate levels. Thus, supplementation is necessary for most people. Indeed, supplementation with vitamin D decreases C-reactive protein (CRP), which is a biomarker of systemic inflammation; supplementation also improves glycemic control and insulin sensitivity.
Sources of vitamin D include:
Fortified milk and cheese
Similar to vitamin A, vitamin E refers to a class of compounds, where the most common ones are known as tocopherols and tocotrienols. Vitamin E is one of the main antioxidant molecules in the body, helping to protect cells from oxidative damage. Deficiency can lead to neurological disorders, inflammation, and metabolic dysfunction. Most people, however, do get adequate amounts if eating a balanced diet and do not require supplementation.
Sources of vitamin E include:
Vitamin K is the name for a family of compounds known as phylloquinones (Vitamin K1) and menaquinones (Vitamin K2). Vitamin K is super important for regulating blood homeostasis by controlling clotting, and it also plays a role in bone formation and remodeling. Vitamin K also works synergistically with vitamin D. Vitamin K1 can be obtained in the diet from plants. Vitamin K2 is a little different in that it is the product of bacterial fermentation and must either by made by gut bacteria, consumed in supplement form, or come from some animal foods. Deficiencies in vitamin K lead to bleeding disorders, where the blood does not clot adequately, making it difficult to stop bleeding. Deficiency in vitamin K can also lead to osteoporosis.
Sources of Vitamin K:
Collard and mustard greens
Thanks so much for reading this post! It is super important to understand micronutrients and what they do in the body because they are so essential for nearly every metabolic reaction in the body. Fat-soluble vitamins (A, D, E, and K) are critical for a myriad of functions in the human body. Vitamin A is important for vision, bone growth, and reproduction, and is typically found in dark, leafy greens, brightly colored fruits, some seafood, liver, and milk products. Consuming a balanced diet typically provides the human body with adequate levels of vitamin A. Vitamin D, which can be found in fatty fish, fish oils, and fortified dairy products, is harder to obtain in a balanced diet, requiring supplementation with this micronutrient for most people. Vitamin D is very important for bone health, immune function, and calcium metabolism. Vitamin E is the main antioxidant in the body, and it is typically found in nuts, seeds, fish, and avocados. Supplementation with vitamin E is generally not needed if consuming a balanced diet. Vitamin K is important in regulating blood homeostasis; supplementation is typically not necessary for vitamin K if consuming a balanced diet.
Check the lists above to find some foods that you enjoy and make sure you are including them in your regular dietary intake. These fat-soluble vitamins play essential roles in the functioning of our body, so be sure to get adequate amounts of them. Please note, however, that fat-soluble vitamins can become toxic if consumed in drastically large amounts.
As always, the information presented in this blog post is derived from my own study of human movement, anatomy and physiology, yoga, and nutrition. If you have questions nutrition for your body, please follow up with your physician, registered dietician, or nutrition coach. If you are interested in nutrition coaching, private yoga, and/or personal training sessions with me, Jackie, email me at email@example.com for more information about my services. Also, please subscribe to my website so you can receive my monthly newsletters (scroll to the bottom of the page where you can submit your email address). This will help keep you "in-the-know" about my latest blog releases and other helpful yoga and wellness information. Thanks for reading!
~Namaste, Jackie Allen, M.S., M.Ed., CCC-SLP, RYT-200, RCYT, NASM-CPT, NASM-CES, NASM-CNC, NASM-SFC