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Signs Your Body Cannot Absorb Vitamin D, According to Doctors

Experts explain why vitamin D is so important and signs that indicate you could be deficient in the essential vitamin. 
FACT CHECKED BY Emilia Paluszek

Getting outside and soaking up the sunshine is sometimes the best medicine when we're feeling down, but that isn't always the case when it comes to vitamin D. We can produce the essential vitamin when we're exposed to sunlight, but it can be challenging for many to get the amount needed. In fact, being deficient in vitamin D is so common, it's a global problem. According to the Cleveland Clinic, "About 1 billion people worldwide have vitamin D deficiency, while 50% of the population has vitamin D insufficiency. Approximately 35% of adults in the United States have vitamin D deficiency." Vitamin D is vital for bone development, healthy teeth and muscles. Without it, our overall health is in jeopardy. "Vitamin D deficiency has been linked with a myriad of acute and chronic illnesses including preeclampsia, childhood dental caries, periodontitis, autoimmune disorders, infectious diseases, cardiovascular disease, deadly cancers, type 2 diabetes and neurological disorders," Dr. Kim Langdon, MD, OBGYN with Medzino tells us. Taking a daily supplement is one way to help ensure you're getting a sufficient amount of vitamin D and Dr. Langdon says vitamins can "support a  healthy immune and cardiovascular system, bone and skeletal health. However, there can be risks involved. Stella Bard, M.D. tells us, "Vitamin D plays an important role in the growth and structure of bones and teeth, and immune function. However, the risk is vitamin D toxicity with overdoing supplementation and leads to hypercalcemia which causes nausea and vomiting, weakness, and frequent urination. bone pain and calcium stones in the kidneys." Eat This, Not That! Health spoke with experts who shared what to know about vitamin D and signs that indicate you could have a deficiency. It's always recommended to speak to your physician before taking supplements and please consult with your doctor for medical advice.  Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Why Deficient in Vitamin D is so Common

woman applying sunscreen lotion standing outdoors at the urban location during the sunny weather

Dana Ellis Hunnes PhD, MPH, RD is a senior dietitian at UCLA medical center, assistant professor at UCLA Fielding school of public health, and author with Cambridge university Press, of the new book, RECIPE FOR SURVIVAL says, "We wear sunscreen, stay inside (with jobs) more, it's approaching winter when there is less UV due to the sun being lower in the sky, our diets are low in vitamin D." Tina Marinaccio MS RD CPT, Integrative Culinary Registered Dietitian Nutritionist with Health Dynamics adds, "Vitamin D deficiencies are common because it is not abundant in the food supply, and most of us here in the US do not live in equatorial regions where we have the opportunity to make enough from the sun. Plus, many people go out of their way to avoid the sun by covering up, wearing sunscreen, and staying out of the sun between ten and 2 to protect against skin cancer. Food sources are limited to fish like salmon, egg yolks, beef liver, and milk, so you can see why most people fall short. In fact, the government started fortifying milk with vitamin D in the 1930's in an effort to eradicate rickets (a bone disease from vitamin D deficiency that causes soft bones) in children." Nancy Mitchell, a Registered Nurse with Assisted Living Center shares, "Vitamin D deficiency is common in areas where there tends to be year-round low temperatures and colder climates. People who live in Canada and colder states are at particular risk of developing Vitamin D deficiency because of their decreased exposure to sunlight due to cloud cover. It's not that you can't receive sunlight and Vitamin D through the cloud cover, but it will require longer periods outdoors to absorb the adequate amounts needed for optimal body functioning. We're also seeing increased incidences of Vitamin D deficiency among remote workers. These workers spend most of their time indoors, even while at home. This makes it virtually impossible to receive adequate daily sunlight exposure.  You have to get outdoors, even if it's just for 30 minutes a day."


Why It's Hard For Some People to Absorb Vitamin D

vitamin d foods

Kelly Johnson-Arbor, MD, FACEP, FUHM, FACMT Medical Toxicologist and Co-Medical Director at the National Capital Poison Center explains, "Although food is a source of vitamins and minerals for many people, very few foods are rich in vitamin D. Cod liver oil, fish (including salmon and trout), and mushrooms are foods high in vitamin D. Because it is challenging to obtain a satisfactory amount of vitamin D from foods, most people must obtain vitamin D through skin synthesis.  However, people who live in climates with low amounts of sunlight, those who wear thick or heavy clothes across most of the body, and who are older, obese, or have darker skin tones may have difficulty synthesizing vitamin D through their skin. These individuals should talk with their doctor about whether vitamin D supplementation is appropriate. The Recommended Daily Allowance for vitamin D in most adults is 600 IU, and this can be achieved through use of oral vitamin D supplementation. However, people with gastrointestinal diseases may have difficulty absorbing vitamin D from the digestive tract."


Signs of a Vitamin D Deficiency


Lisa Richards, a nutritionist and creator of the Candida Diet tells us, "Signs and symptoms of a vitamin D deficiency can easily be passed off as just a side effect of your busy and exhausting lifestyle. But, chronic fatigue and other symptoms can be signs of a serious vitamin D deficiency. Other surprising signs of vitamin D deficiency include hair loss, muscle pain, and depression." Emma Louise Kirkham Women's Hormone Health Coach & Dietary Supplements Advisor says, "Deficiency in vitamin D can be exhibited as back pains, joint pain or stiffness, muscular twitches or spasms, weakened bones, arthritis of osteoporosis, hair loss, tooth decay, fatigue and often getting ill. In addition to this women may experience premenstrual syndrome, PCOS or fertility struggles which are also linked to vitamin D deficiency (amongst other nutritional deficiencies)."


What to Know Before Taking Vitamin D

fresh seafood plate

Kelsey Mauro, a Board Certified Dermatology Physician Assistant and a Functional Medicine Gut Health Consultant/Holistic Medicine Provider explains, "There has been a link of lack of Vitamin D and risk of dementia as well as stroke in individuals.  It can be challenging to absorb vitamin D when you have certain medical problems such as Crohn's disease, celiac disease or cystic fibrosis. To increase absorption, you can include Vitamin K, magnesium and zinc into your diet, increase healthy fats into your diet such as ghee, and eat more seafood in your diet as the Vitamin D in seafood is better absorbed compared to plant-based sources. Before you take a Vitamin D supplement you should know that it is a fat-soluble vitamin so consuming it with fat will increase its absorption and taking too much can lead to vitamin D toxicity and cause nausea and dehydration." Marinaccio adds, "Vitamin D is fat soluble, so it's best to take with a fatty meal for absorption. Many people take supplements at breakfast, so if you're having tea with nonfat milk, and toast with jam, you're not going to absorb it. Either take vitamin D with a later meal in the presence of fat, or add some fat to your breakfast, like a schmear of avocado or nut butter on your toast. For ease of use, I like vitamin D in liquid form. I recommend vitamin D with added vitamin K2 to promote bone both bone and cardiovascular health."


The Benefits and Risks of Taking Vitamin D

vitamin D3

Dr. Jacob Hascalovici MD, PhD, Clearing Chief Medical Officer explains, "The benefits of vitamin D intake include protecting your bones, potentially helping stabilize your mood, and possibly fighting cancer. It's clear that vitamin D is essential and that the body suffers if you do not get enough of it. It's important not to exceed 4,000 IU per day, as too much vitamin D can contribute to nausea, vomiting, kidney stones, heart damage, and cancer. In rare cases, vitamin D build up over time can lead to calcium-related toxicity."  Dr. Johnson-Arbor shares, "The benefits of vitamin D supplementation may include enhanced bone health, decreased inflammation, and improved heart health. Although vitamin D toxicity is rare, it does happen, so seek medical attention or contact Poison Control if you develop unwanted or unexpected signs or symptoms after taking vitamin D supplements. There are two ways to contact Poison Control: online at or by phone at 1-800-222-1222. Both options are free, confidential, and available 24 hours a day." Mauro says, "The benefits of taking Vitamin D daily is that Vitamin D can reduce inflammation, strengthen your immune system, help lower blood pressure, may reduce the risk of heart disease and may prevent certain types of cancer.  The risks of taking Vitamin D daily is taking too much which can cause harmful high calcium levels in your blood which can potentially form deposits in your arteries or soft tissues.  This can also lead to an increased risk of painful kidney stones."  Kirkham adds, "Sometimes you may see vitamin D listed in a unit size of IU. Each 100IU is 2.5mcg. The RDA is 5mcg, but the ideal levels of intake are 11mcg. If you are struggling with bone health or premenstrual syndrome, looking for vitamin D combined with calcium can be beneficial and the calcium will also help promote the absorption of the vitamin D. When it comes to vitamin D, this should be taken with foods that contain healthy fats or oils to promote the absorption, however low levels of bile can actually hinder the absorption. As with any vitamin, it can take several weeks to start seeing improvements from supplements, and any requirements for dietary supplements should be reviewed every three months. Supplements alone can only do so much thought, dietary and lifestyle changes should also be considered. Taking vitamin D daily can help boost levels of immunity, help protect our bone health and support our hormonal imbalances (in conjunction with dietary and lifestyle changes). Taking too much vitamin D can actually be harmful. This is because it encourages calcium absorption, too much can cause the calcification of the soft tissue where it may worsen issues such as the hardening of the arteries or cause the development of kidney stones. As such, it's recommended that only 3-5 mcg of vitamin d are taken as a supplement depending on each individual's needs."

Heather Newgen
Heather Newgen has two decades of experience reporting and writing about health, fitness, entertainment and travel. Heather currently freelances for several publications. Read more about Heather
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