by Linda Atchley, R.N., Physician Assistant
Our Heavenly Father has spoken clearly in His Word about health, sickness, and disease. As 3 John 1:2 says, "Dear friend, I pray that you may prosper in every way and be in good health physically just as you are spiritually" (HCSB). Not only should our first important objective be to become more like our Lord Jesus Christ every day and bring Him glory, but He also expects us to take responsibility for doing what we can to take care of the body He’s given us. Toward that, we’ll discuss in this article the importance of vitamin D and the crucial role it plays in our health.
First, a brief history of vitamin D and then the many health benefits of this amazing, essential nutrient created by our Heavenly Father.
A vitamin D deficiency disease is "rickets"—the softening and weakening of bones in children. The illness was prevalent in the seventeenth century, particularly in Europe. Rickets was first recognized in the 1600s and became more common in the 1700s and 1800s as more people spent time indoors in their industrialized cities. The 1920s’ discovery of vitamin D and its ability to be synthesized in the skin after sunlight exposure led to a better understanding of rickets and treatment of the disease.
The Recommended Dietary Allowance (RDA) of vitamin D was established in 1941. That same year, the recommended "inaugural value"1 for adults was placed at 400 IUs, where it closely remained until 2011. The updated RDA was then set at 600 IUs for adults and 800 IUs for age seventy and older. In the 1960s, the American Academy of Pediatrics (AAP) recommended 400 IUs for infants and children, which is still the AAP recommendation today.
So, how important is vitamin D now and how much should we take daily? According to today’s scientists, physicians, and other health experts, achieving "optimal levels"2 of vitamin D-3 (25-hydroxycalciferol) is vitally important. The recommended level range is between 50-80 ng/mL for most adults. However, dosage varies depending upon who is receiving the supplement—infants, children, adults, or the elderly—and such factors as heavy or obese weight, the amount of sun exposure, and the medications prescribed.
One of the first questions you may now be asking is, "How do I know if I’m deficient in vitamin D-3?"
Since The American Society of Clinical Pathology (2018) does not recommend routine monitoring of vitamin D levels, most physicians do not regularly check their patients’ vitamin D-3 levels. Therefore, I recommend that you ask your physician to test your vitamin D-3 level to establish a baseline. Why is this important? Let’s look closely at the opinions of several vitamin D experts, scientists, and functional medicine physicians and why, based on their research, they believe you should supplement with vitamin D and have your level checked twice a year. Sources on the importance of vitamin D include the following.
Dr. Mark Hyman, a functional medicine internist, said, "70 percent of Americans have either deficient or suboptimal levels of vitamin D. . . . a massive problem given vitamin D’s impact on our health and . . . our gene regulation and expression."3 He believes that vitamin D plays a crucial role in cell function and immunity, making deficiency particularly impactful on overall health. He also highlights that a deficiency can contribute to conditions such as cancer, heart disease, diabetes, depression, and even severe COVID-19 complications.
At The Block Center for Integrative Cancer Treatment in Chicago, Illinois, a vitamin D-3 level of 60-100 ng/mL is the goal for their patients.
Dr. David Perlmutter, an integrative neurologist, has highlighted the significant impact of vitamin D on both brain function and the immune system, suggesting that it plays a role in reducing dementia risk and supporting overall brain health. He cites studies showing a correlation between vitamin D exposure and a lower dementia incidence. A source explains Dr. Perlmutter’s view: "vitamin D helps keep the brain healthy by supporting the growth and survival of brain cells." The source quotes Dr. Perlmutter as saying, "It also reduces inflammation, a key mechanism behind what makes a good brain go bad."4
Dr. Joseph Mercola, a functional medicine family physician, says that optimal vitamin D levels result in stronger bones (no rickets or osteomalacia), better immunity (fighting viruses and lowering the risk of infections), lower chronic disease risk (less heart disease, diabetes, and cancer), a healthier gut, fewer autoimmune problems (MS, RA, Psoriasis), and a "happier mood"5 (reducing risks of depression and anxiety).
Dr. Michael Holick, Professor of Medicine, Physiology, Biophysics and Pharmacology at Boston University School of Medicine and world’s leading expert on vitamin D says that vitamin D deficiency is significantly under-diagnosed. His research has shown that vitamin D is very important for bone health, the immune system and during pregnancy. Dr. Ford Brewer, cardiologist, says that adults should take vitamin K2-MK7 with their vitamin D to make sure calcium is deposited in the bones versus the arteries. According to Dr. Holick, vitamin D is critically important for pregnant women and newborns. Based on his studies, 76 percent of pregnant mothers and 81 percent of newborns are vitamin D deficient!
The Endocrine Society’s 2024 guidelines for Vitamin D "suggest empiric vitamin D supplementation during pregnancy, . . . to lower risk of preeclampsia, intra-uterine mortality, preterm birth, small for gestational age birth, and neonatal mortality"6—all of which can be caused by very low vitamin D levels. The data in his multiple studies clearly proves the importance of vitamin D to the health of pregnant women and their newborns. Dr. Holick’s research also suggests a potential link between low vitamin D levels and an increased risk of certain cancers.
In that respect, Dr. William B. Grant, PhD—a leading expert on vitamin D and cancer with 163 publications of his over 284 at PubMed.gov concerning the relationship of vitamin D to cancer—wrote, "As an affordable natural agent, vitamin D3 can be used to counteract obesity-induced inflammation, block early adipogenesis, enhance glucose uptake, counteract hyperleptinemia, ameliorate insulin resistance, and reduce hypertension."7 The abstract, co-authored by Dr. Meis Moukayed, PhD, suggests that vitamin D-3 significantly lowers the risk of multiple cancers.
As these researchers and physicians have shown, optimal blood levels of vitamin D can reduce the risk of several diseases. Therefore, monitoring your vitamin D level twice a year is greatly beneficial and also inexpensive. Likewise, important to recognize is that several factors mentioned above—such as one’s age, obesity, sun exposure, and medications—can also determine the needed dosage. Most people will not be able to absorb enough vitamin D from the sun, so supplementation is needed and should be taken preferably in the morning with food that contains healthy fat.
Now that you know how important vitamin D is to the health of your God-given body, why wait any longer to supplement and experience the benefits?
Please email me at linda.atchley@gmail.com with any questions.
Blessings!!
Linda Atchley, R.N., Physician Assistant
Notes:
1. MS, Whiting SJ, Calvo M. "Dietary Recommendations for Vitamin D: A Critical Need for Functional End Points to Establish an Estimated Average Requirement." The Journal of Nutrition. Accessed November 20, 2025. https://pubmed.ncbi.nlm.nih.gov/15671232/.
2. K. A. Kennel and M. T. Drake, "Vitamin D Deficiency in Adults: When to Test and How to Treat," Mayo Clinic Proceedings 85, no. 8 (2010): 752–757, https://pmc.ncbi.nlm.nih.gov/articles/PMC2912737/
3. YouTube video, (video length), posted [date of upload], https://www.youtube.com/watch?v=LTuZfI4EV_4.
4. "Vitamin D Could Help Lower Dementia Risk—Are You Getting Enough?" Yahoo Lifestyle, May 15, 2025. https://www.yahoo.com/lifestyle/vitamin-d-could-help-lower-160013868.html
5. Joseph Mercola, "Higher Vitamin D Levels Linked to Improved Mental Health," Mercola.com, September 28, 2024, https://articles.mercola.com/sites/articles/archive/2024/09/28/vitamin-d-mental-health.aspx
6. Marie B. Demay et al., Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline, The Journal of Clinical Endocrinology & Metabolism 109, no. 8 (2024): 1907–1947, https://doi.org/10.1210/clinem/dgae290
7. Moukayed, M. and Grant, W. B. (2019). Linking the metabolic syndrome and obesity with vitamin D status: risks and opportunities for improving cardiometabolic health and well-being. Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy, 12, 1437–1447. DOI:10.2147/DMSO.S176933. PMC6701609.
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