Vitamin D is a fat-soluble nutrient. Its biggest source is actually the sun as it helps the skin produce 50–90% of your vitamin D intake. Food sources like egg yolk, fortified dairy products, fatty fish, and beef liver offer small amounts of vitamin D too. As a steroid with hormone-like activity, vitamin D is crucial for growth and development.
Unfortunately, many of us are deficient in it. Over a billion people around the world don’t get enough vitamin D.1 In the United States, 25% of the population is at risk of inadequacy while 8% is at risk of deficiency.2 People who work indoors, wear excess clothing, and have darker skin tend to be at a higher risk for vitamin D deficiency.3
1. Low Mood
Vitamin D is needed to convert tryptophan into serotonin, a brain chemical that regulates mood, decision making, and social behavior. Low levels of vitamin D mean low serotonin, which leads to feelings of sadness and depression.4 Vitamin D deficiency is the reason why seasonal affective disorder, or SAD, is so common during the dreary months of winter. Many people feel lethargic, drowsy, and the need to socially hibernate.5 In the case of SAD, vitamin D supplements can make up for the lack of sun.
Nutrients like vitamin C and zinc are often associated with the immune system. However, vitamin D can aid T-helper cells, making it a vital part of the team.6 A 2012 study in the Journal of Investigative Medicine also found that vitamin D helps white blood cells make more bacteria-fighting proteins.7 So, if you don’t consume enough vitamin D, you are likely to suffer from immunity problems.
3. Respiratory Infections
Adults and children with low vitamin D levels are known to suffer from frequent coughing and upper respiratory tract infections.8 With vitamin D’s immunity-boosting benefits, recurring episodes may be prevented. Moreover, research has even shown benefits of vitamin D for treating and preventing tuberculosis.9 So, insufficient vitamin D is likely to have damaging effects on your respiratory tract.
4. Muscle Weakness
Did you know that muscles contain vitamin D receptors? However, without enough of this nutrient, muscles can become weak. This, in turn, can lead to poor balance and physical function, increasing the risk of injuries and falls.10 For older adults who stay indoors, adequate vitamin D is especially important.
Calcium might be vital for healthy bones, but it can’t keep bones strong by itself. Vitamin D aids absorption and maintains homeostasis of the mineral, which explains why calcium supplements often have added vitamin D. A low intake of vitamin D can lead to weakness, brittle bones, and pain, especially in the lower back, low extremities, and pelvic area.11 12 Over time, vitamin D deficiency can severely increase the risk of osteoporosis, especially in postmenopausal women.13
6. Neurodegenerative Diseases
Now that you know the health risks caused by vitamin D deficiency, it’s important to know how much your vitamin D intake should be.
How Much Is Enough?
For people from ages 1 to 70, including pregnant and breastfeeding women, the recommended intake is 600 IU. Adults who are 71 and older need 800 IU.
The upper limit is 4,000 IU a day. Any more than that may lead to toxicity and cause nausea, vomiting, weight loss, and kidney damage. Only take more than 4,000 IU if your doctor says so.16
To avoid vitamin D deficiency, spend 15 to 20 minutes in the sun each day. About 40% of your skin should be exposed. If you have dark skin, talk to your doctor for a personalized recommendation as melanin can slow down vitamin D production.17
|↑1, ↑3, ↑17||Naeem, Zahid. “Vitamin D deficiency-an ignored epidemic.” International journal of health sciences 4, no. 1 (2010): V.|
|↑2||Looker, Anne C., Clifford L. Johnson, David A. Lacher, Christine M. Pfeiffer, Rosemary L. Schleicher, and Christopher T. Sempos. “Vitamin D status: United states, 2001–2006.” NCHS data brief 59, no. 59 (2011): 1-8.|
|↑4||Patrick, Rhonda P. and Bruce N. Ames. “Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar, schizophrenia, and impulsive behavior.” The Office Journal of the Federation of American Societies for Experimental Biology 29.6 (2015): 2207-2222.|
|↑5||Seasonal Affective Disorder. National Institute of Mental Health.|
|↑6||Hossein-nezhad, Arash and Michael F. Holick. “Vitamin D for Health: A Global Perspective.” Mayo Clinic Proceedings 88.7 (2013):720-755.|
|↑7, ↑9||Aranow, Cynthia. “Vitamin D and the Immune System.” Journal of Investigative Medicine : The Official Publication of the American Federation for Clinical Research 59.6 (2012):881–886.|
|↑8||Vitamin D and Health.
|↑10, ↑12||Bordelon, Paula, Maria V. Ghetu, and Robert Langan. “Recognition and Management of Vitamin D Deficiency.” American Family Physician 80.8 (2009): 841-846.|
|↑11, ↑13||Vitamin D. National Institutes of Health.|
|↑14||Zhao, Yan, Yan Sun, Hong-Fang Ji, and Liang Shen. “Vitamin D levels in Alzheimer’s and Parkinson’s diseases: a meta-analysis.” Nutrition 29, no. 6 (2013): 828-832.|
|↑15||Koduah, Priscilla, Friedemann Paul, and Jan-Markus Dörr. “Vitamin D in the prevention, prediction and treatment of neurodegenerative and neuroinflammatory diseases.” EPMA Journal (2017): 1-13.|