In a 2013 issue of Vitamin Retailer I wrote an article titled, “Vitamin D: A Research Update.” Then, in the February 2024 issue of Vitamin Retailer I wrote an article titled, “Synthetic vs. Vegan D3: Impact on Health & Sustainability.” So why write another article on vitamin D? The answer is that there is so much new research taking place on the clinical applications of vitamin D that an updated review is in order. That is the purpose of this current article.

Background Information

Vitamin D is both a nutrient we consume and a hormone our bodies make. It has also been referred to as the “sunshine vitamin” because exposure to the sun’s ultraviolet light will convert a form of cholesterol under the skin into vitamin D. It is a fat-soluble vitamin that has long been known to help the body absorb and retain calcium and phosphorus. As such, vitamin D is critical for building bones and as well as its effects as a potent immune system modulator.1 Consequently, it is problematic that 29 percent of the U.S. population is vitamin D deficient and an additional 41 percent are vitamin D insufficient.2

Now, let’s look at some more recent research demonstrating vitamin D’s beneficial effects on different categories of human health and well-being, including respiratory health, skin health, prenatal and neonatal health, blood pressure, multiple sclerosis and colorectal cancer. In addition, vitamin D supplementation guidelines and dosage will be addressed, as will this nutrient’s importance in the winter.

Respiratory Health

Vitamin D supplementation has been shown to be beneficial for various respiratory health disorders:

• Allergic Rhinitis (Hay Fever): In clinical research,3 supplementation with 50,000 IU/week along with cetirizine (e.g., Zyrtec) in adults with allergic rhinitis and vitamin D deficiency resulted in improvement of overall symptom severity when compared with placebo and cetirizine. Similar results with children were seen with vitamin D supplementation of 800 IU or 1,000 IU/day.4 Additional research5 likewise showed improvements in allergic rhinitis symptoms in children and adults supplemented with 4,000 or 5,000 IU/day.

• Asthma: Population research6 in asthmatics has found that low vitamin D levels are associated with an increased risk for worsening of symptoms. Meta-analyses7-10 of adults and children with asthma demonstrated that vitamin D supplementation reduces the rate of worsening symptoms by 31 percent to 36 percent when compared with control. Vitamin D doses have included 500-4,000 IU daily, 60,000 IU once monthly, 120,000 IU every two months, 100,000 IU 14 days apart.

• COPD: A randomized, single-center, double-blind, placebo-controlled trial11 in patients with moderate to severe chronic obstructive pulmonary disease (COPD) and severe vitamin D deficiency showed that supplementing with vitamin D 100,000 IU once every four weeks for one year reduced symptoms by 43 percent when compared with placebo.

Skin Health

Vitamin D has a positive impact on skin health:

• Acne: Studies12,13 have demonstrated that vitamin D deficiency was about three times higher in patients with acne when compared with healthy controls, and when patients with acne and vitamin D deficiency were supplemented with vitamin D3 1,000 IU daily for two months, there was a reduction in the number of inflammatory lesions by about 35 percent, compared with 6 percent in those taking placebo.

• Atopic Dermatitis (Eczema): A meta-analysis14 in children showed that supplementation with 1,000-2,000 IU/day vitamin D for four to 12 weeks significantly reduced Scoring Atopic Dermatitis or the Eczema Area and Severity Index scores in children with atopic dermatitis compared with placebo (p=0.009).

• Ichthyosis: A randomized, double-blinded study15 in patients with congenital non-syndromic ichthyosis (a group of skin disorders that lead to dry, itchy skin that appears scaly, rough and red) showed that supplementation with vitamin D 2,000 IU daily for 24 weeks reduced the clinical severity of disease at 12 weeks compared with baseline.

• Urticaria: A meta-analysis16 showed that there was a greater likelihood of vitamin D deficiency in individuals with urticaria (a rash of round, red welts on the skin which itch intensely, sometimes with dangerous swelling, caused by an allergic reaction, typically to specific foods) compared to those without. In addition, taking at least 4,100 IU vitamin D/day resulted in a significant reduction on the severity of urticaria symptoms.

Prenatal and Neonatal Importance of Vitamin D

Vitamin D has been shown to play an important role in both prenatal and neonatal health: • Preterm birth: Black people have more melanin in their skin, affecting the body’s ability to synthesize vitamin D.17 Research18 has shown that, in pregnant black women with vitamin D deficiency the odds of preterm birth were increased by 3.34 times.

• Childhood Asthma: A study19 showed that the use of vitamin D supplementation along with a standard prenatal multivitamin (providing a total of 4,400 IU/day) resulted in a statistically significant reduction in asthma among offspring aged 3 and 6 years compared to the prenatal multivitamin with only 400 IU/day vitamin D.

• Neonatal Vitamin D Status: Vitamin D deficiency is common in pregnancy and associated with an increased risk of adverse pregnancy outcomes. A study20 was conducted to compare maternal vitamin D supplementation of 10 mcg/day (i.e., 400 IU) to 90 mcg (3,500 IU) to assess neonatal vitamin D status. Results were that about 51 percent of neonates in the 10 mcg vitamin D group were vitamin D-deficient in contrast to only 11 percent in the 90 mcg group.

Vitamin D and Blood Pressure

Research indicates that supplementation with vitamin D may help manage blood pressure: • In Type 1 Diabetes: A 12-week prospective controlled pilot study21 found that vitamin D3 supplementation (4,000/10,000 IU/day) in patients with type 1 diabetes mellitus (T1DM) and associated cardiovascular autonomic neuropathy (CAN) improved CAN parameters and reduced morning systolic blood pressure (SBP, p = 0.038) and in morning SBP surge (p = 0.04).

• BP & Heart Rate: An eight-week, prospective, randomized, double-blind clinical trial22 in obese/overweight 53 individuals with low vitamin D levels demonstrated that supplementation with 7,000 IU/day vitamin D significantly improved vitamin D levels (p<0.001), and reduced SBP (p=0.019), and alkaline phosphatase p=0.012).

Multiple Sclerosis, Colorectal Cancer and Vitamin D

Vitamin D supplementation may have a positive role to play in patients with multiple sclerosis and colorectal cancer:

• Multiple Sclerosis: A two-year, parallel, double-blind, randomized placebo-controlled clinical trial23 evaluate the efficacy of high-dose cholecalciferol (100,000 IU, n = 163) every two weeks compared to placebo (n = 153) in patients with clinically isolated syndrome (CIS) typical for multiple sclerosis (MS). Results were that disease activity was observed in 94 patients (60.3 percent) in the vitamin D group and 109 patients (74.1 percent) in the placebo group (P=0.004) ), and median time to disease activity was longer in the vitamin D group (432 vs 224 days; P=0.003).

• Colorectal Cancer Patients: A single-blind, randomized controlled trial (RCT)24 was conducted to assess the effect of vitamin D supplementation (n=34) or placebo (n=34) on the quality of life of stage II-III colorectal cancer patients undergoing chemotherapy. Results were that serum vitamin D levels significantly increased (p < 0.001) in the intervention arm but decreased in the placebo arm. The patients’ quality of life improved significantly after receiving vitamin D, compared with the placebo group.

Vitamin D Supplementation Guidelines & Dosage

Research has provided guidelines for the use of vitamin D, and appropriate dosage levels: • Endocrine Society Guidelines: The Endocrine Society published clinical practice guidelines for supplementation of vitamin D.25 Recommendations for supplementation included:

o Children and adolescents to prevent rickets and reduce potential risk of respiratory tract infections,

o Those aged 75 years and older because of its potential to lower the risk of mortality,

o Those who are pregnant to lower the risk of pre-eclampsia, intra-uterine mortality, preterm birth, small-for-gestational-age birth and neonatal mortality,

o Those with high-risk prediabetes reduce risk of progression to diabetes.

• Daily Dose of 2,000 IU: A review published in the journal Nutrients26 outlined and discussed various societies and expert groups recommendations for daily vitamin D supplementation with 2,000 IU (50 mcg) of vitamin D3 to prevent and treat vitamin D deficiency.

• Athletes: A 10-week randomized controlled intervention study27 in athletes found that a loading dose of 4,000 IU of vitamin D daily was more effective than a loading dose of 2,000 IU/day, followed by a maintenance dose of 1,000 IU/day, for restoring adequate vitamin D levels in athletes.

• Wintertime: A worldwide study28 on vitamin D deficiency with 7.9 million participants from 81 countries found that the prevalence of vitamin D deficiency was 1.7 times higher in winter–spring than that in summer–autumn. Research29 suggests that 2,000 IU/day of vitamin D3 was more effective at maintaining healthy vitamin D levels.

Different Sources

Cholecalciferol (vitamin D3) is the form of vitamin D made in the human body, and it is more active than ergocalciferol (vitamin D2). In fact, vitamin D2 potency is less than one third that of vitamin D330—so D3 is generally considered the preferred form of vitamin D. That being said, there are a few available sources of vitamin D3:

• Animal/Synthetic Vitamin D: Most commercial vitamin D3 is derived from sheep wool-sourced lanolin, which undergoes a synthetic process in the lab to become D3. It is not a natural, vegan, sustainable or non-GMO (genetically modified organism) source. That doesn’t mean that it isn’t good. Plenty of research shows that it works well. However, if you want a natural source, this isn’t it.

• Vegan Vitamin D: There are also a few plant-derived, vegan sources of vitamin D3. These include lichen and algae sources. Even so, it is vitally important to know the exact species of lichen or algae if you’re going to use it as a source of D3 in a dietary supplement since there are more than 20,999 lichen species31,32 some of which are rare or endangered, and some that contain toxic compounds as well. Likewise, there are about 320,500 algae33,34 including some harmful to human health. Also, without knowing the alga source, there is no way to independently confirm if it is from clean or polluted waters.

As I indicated in a previous article, my personal favorite source of vegan vitamin D3 is one extracted from reindeer lichen aka, Cladonia rangeiferina (VegaDelight from Nutraland USA). This plant has an extensive history of use as a food35 and natural medicine36-38 by indigenous people of various cultures. In addition, reindeer lichen is a widespread, sustainable and abundant plant,39 and not on the endangered or threatened species list.40,41 Furthermore, to the best of my knowledge, and at the time of this writing, this unique reindeer lichen source of vitamin D us the only plant source in which the actual genus and species is identified.

Conclusion

In addition to vitamin D’s well-known role in facilitating calcium absorption, promoting bone health and immune health, new research has demonstrated that vitamin D also offers meaningful benefits in support of respiratory health, skin health, prenatal and neonatal health, blood pressure, multiple sclerosis and colorectal cancer. Furthermore, research has provided guidelines for the use of vitamin D, appropriate dosage levels and its importance in the winter. Finally, reindeer lichen is a sustainable, vegan source of vitamin D3.VR

Gene Bruno, DBM, MHS, Professor Emeritus of Nutraceutical Science, is a writer, educator and a nutraceutical scientist with more than 45 years of experience educating natural product retailers and health care professionals and formulating natural products for dozens of dietary supplement companies. He has written articles on nutrition, herbal medicine, nutraceuticals and integrative health issues for trade, consumer magazines and peer-reviewed publications. Dr. Bruno also hosts “The Vitamin Professor Podcast” brought to you by VRM Media. He can be reached at [email protected].

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