Timing Vitamin D: Vitamin D is a crucial vitamin that acts like a hormone in the body. With such a profound role, the big question is, are you getting enough? Unfortunately, between food and sunlight, the answer for most people is no. This article covers all things vitamin D, including how to get the most out of your supplementation.

This article has been medically reviewed by Dr. Charles Penick, MD

Why Vitamin D is So Important

Although Vitamin D is considered a vitamin, it behaves like a hormone in the body. This hormone plays a role in various bodily functions. For example, vitamin D controls calcium levels in the blood, a prerequisite for bone development and health ^1.

People with higher vitamin D levels have a lower risk of many diseases, including heart disease, depression, breast cancer, colon cancer, and prostate cancer ^2-3. In addition, vitamin D has been shown to help treat various illnesses, including autism, autoimmune conditions, chronic pain, diabetes, the flu, neuromuscular diseases, and osteoporosis ^4-6.

Signs You Have a Vitamin D Deficiency

Vitamin D deficiency plays a crucial role in many bodily functions, so unsurprisingly, you will get a hefty set of symptoms when your levels are chronically low. Some of the most common signs of vitamin D deficiency include:

• Poor bone health ¹
• Poor immune system resilience ⁴
• Low or unstable moods ² 
• Brain fog and poor memory ⁷

Should You Take a Vitamin D Supplement?

The reality of modern living for most people comes at the cost of getting enough natural vitamin D. There are not many food sources rich in vitamin D. The typical daily exposure to the UVB from the sun to synthesize vitamin D is also too low ^8.

Vitamin D is a fat-soluble vitamin that will bioaccumulate in your body. Getting enough vitamin D in the summer months will keep you going all winter long as it slowly depletes. Still, unfortunately, most people don’t get anywhere near enough sunshine in the summer to last them the winter. Most don’t even get enough to benefit from adequate levels in the summer itself ^9!

One study of Americans measured the average serum 25-hydroxyvitamin D [25(OH)D] levels in adults at the end of winter and the following summer ^9. At the end of winter, levels hovered around 18 to 22 ng/ml and only rose to about 29 ng/ml by the end of summer. Both fall below the 30 ng/ml cutoff, considered the absolute baseline for vitamin D sufficiency. Thirty ng/ml is nowhere near optimal; ideal ranges are upwards of 50 ng/ml.

About 30% of the U.S. population is deficient in vitamin D, but the majority is nowhere near optimal levels of over 50 ng/ml ^10. Vitamin D supplementation is likely beneficial for most Americans as it plays a significant role in generating overall health.

How to Get the Most Out of Your Vitamin D

Whether you’re getting it from food, sunshine, or a supplement, you can do some key things to optimize your absorption.

Food

There are few sources of vitamin D-rich foods, but you can still get some vitamin D in your nutrition by optimizing the quality. Certain foods, like egg yolks, red meat, and oily fish, naturally contain vitamin D. Reaping the benefits requires investing in high-quality eggs, meat, or fish from an animal that lived a life outdoors. The more access to sunshine, the more vitamin D will be stored in the fatty cuts of these animals’ foods^1.

Otherwise, most of the foods that are “high” in vitamin D are fortified foods, which are not ideal sources of vitamin D. This is because these foods tend to be poor-quality foods with cheap vitamin D fortification. So if you’re going to supplement with vitamin D, you’re better off investing in a high-quality vitamin D supplement that you know and trust.

Sunshine

Getting enough vitamin D from the sun requires diligent exposure all summer long. We build up vitamin D stores in the body, so daily exposure when UVB is high is needed. Exposure must be directly onto bare skin, without sunscreen. Exposure must also be direct to the sun since the UVB rays do not penetrate through windows ^12.

Using an SPF-free oil (like coconut oil) can help absorb vitamin D, which is created on the skin, and then absorbed ^13. However, since most people work during peak UV times, it can be difficult, if not impossible, to get adequate daily exposure. In addition, since vitamin D levels build up very slowly over time, you may require a supplement to ensure your levels are high enough all year long.

Supplementation

First of all, supplementation with vitamin D requires consistency. For best results, you should take vitamin D daily. The actual time of day makes no difference, but what you eat with it will either help or impair absorption, so timing it appropriately for the other things you’re consuming at the time.

As a fat-soluble nutrient, it’s essential to take your vitamin D supplement with moderate amounts of fat. Some supplements combine the two, but typically not, so your best bet is to just take it at a time when you consume fat like olive oil or avocado. So, for example, if you’re taking it first thing in the morning, you could have a spoonful of olive or coconut oil simultaneously.

Studies highlight that too little, or too much fat with your vitamin D supplement will impair absorption. One study’s “sweet spot” seems to be around 11 grams. The study compared taking a vitamin D supplement with high (35 grams), moderate (11 grams), or no fat, and the moderate-fat group faired best for overall absorption ^14.

Caffeine impairs vitamin D absorption, so if you can take your vitamin D supplement (with some fat!) first thing before having caffeine, do that. Otherwise, take it with lunch, or with dinner ^15. Consistency is key, so taking it routinely at a time of day, like with breakfast, lunch, or dinner, may help you remember it.

Adequate magnesium levels are also needed in the body to optimize vitamin D absorption, so you may want to consider taking a high-quality mag supplement daily or using a topical magnesium spray.

Summary

Vitamin D is a crucial vitamin that acts like a hormone in the body. With such a significant role, ensuring we get enough is essential. Although vitamin D is a fat-soluble vitamin that is stored in the body, most people don’t get enough exposure to last them in the winter or even benefit from them during the summer.

You can get some from your food, especially animal products that were pasture-raised in the sunshine. Optimizing your vitamin D levels in the summer requires daily exposure to bare skin (without sunscreen) and can be increased by using an SPF-free oil. Supplementation is likely needed for most Americans and should be taken with fat and away from caffeine for better absorption.

Medical Disclaimer: information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended to share knowledge and information. This article has been medically reviewed by Dr. Charles Penick, MD, for the accuracy of the information provided, but we encourage you to make your own healthcare decisions based upon your research and in partnership with a qualified healthcare professional.

References

1. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. “Overview of Calcium.” Dietary Reference Intakes for Calcium and Vitamin D., U.S. National Library of Medicine, 1 Jan. 1970, www.ncbi.nlm.nih.gov/books/NBK56060/.
2. Menon, Vikas et al. “Vitamin D and Depression: A Critical Appraisal of the Evidence and Future Directions.” Indian journal of psychological medicine vol. 42,1 11-21. 6 Jan. 2020, doi:10.4103/IJPSYM.IJPSYM_160_19
3. Garland, Cedric F et al. “The role of vitamin D in cancer prevention.” American journal of public health vol. 96,2 (2006): 252-61. doi:10.2105/AJPH.2004.045260
4. Martens, Pieter-Jan et al. “Vitamin D’s Effect on Immune Function.” Nutrients vol. 12,5 1248. 28 Apr. 2020, doi:10.3390/nu12051248
5. Cannell, John Jacob. “Vitamin D and autism, what’s new?.” Reviews in endocrine & metabolic disorders vol. 18,2 (2017): 183-193. doi:10.1007/s11154-017-9409-0
6. Sunyecz, John A. “The use of calcium and vitamin D in the management of osteoporosis.” Therapeutics and clinical risk management vol. 4,4 (2008): 827-36. doi:10.2147/tcrm.s3552
7. “Cognitive Consequences of Vitamin D Deficiency.” Practical Neurology, Bryn Mawr Communications, practicalneurology.com/articles/2014-jan-feb/cognitive-consequences-of-vitamin-d-deficiency.
8. Holick, Michael F. The Vitamin D Solution: a 3-Step Strategy to Cure Our Most Common Health Problems. Plume, 2011.
9. Kroll, Martin H et al. “Temporal relationship between vitamin D status and parathyroid hormone in the United States.” PloS one vol. 10,3 e0118108. 4 Mar. 2015, doi:10.1371/journal.pone.0118108
10. Liu, Xuefeng et al. “Vitamin D deficiency and insufficiency among US adults: prevalence, predictors and clinical implications.” The British journal of nutrition vol. 119,8 (2018): 928-936. doi:10.1017/S0007114518000491
11. Kühn, Julia et al. “Free-range farming: a natural alternative to produce vitamin D-enriched eggs.” Nutrition (Burbank, Los Angeles County, Calif.) vol. 30,4 (2014): 481-4. doi:10.1016/j.nut.2013.10.002
12. Nair, Rathish, and Arun Maseeh. “Vitamin D: The “sunshine” vitamin.” Journal of pharmacology & pharmacotherapeutics vol. 3,2 (2012): 118-26. doi:10.4103/0976-500X.95506
13. Lin, Steven “Vitamin D Through Sun: 9 Tips to Optimize Your Levels.” Dr. Steven Lin, 22 Sept. 2018, www.drstevenlin.com/optimize-vitamin-d-through-sun/.
14. Dawson-Hughes, Bess et al. “Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementation.” Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research vol. 28,8 (2013): 1778-83. doi:10.1002/jbmr.1896
15. Rapuri, Prema B et al. “Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells.” The Journal of steroid biochemistry and molecular biology vol. 103,3-5 (2007): 368-71. doi:10.1016/j.jsbmb.2006.12.037