Vitamin D: Essential for Good Health

Feb 09, 2022

Vitamin D: Essential for Good Health

The awareness of the need for vitamin D for overall health has increased in recent years. Research continues to demonstrate that this essential fat-soluble vitamin is important for immune and bone support and other health states because vitamin D receptors are found throughout the body.1 Our skin has the unique ability to make vitamin D through UVB rays, but since it is advisable to limit sun exposure, our bodies may not be making adequate amounts for optimal health. Additionally, few foods naturally contain vitamin D, and fortified foods contain minimal amounts of this nutrient.2 An analysis of data from the 2015–2016 National Health and Nutrition Examination Survey (NHANES) found that average daily vitamin D intakes from foods and beverages were 5.1 mcg (204 IU) in men, 4.2 mcg (168 IU) in women, and 4.9 mcg (196 IU) in children aged 2–19 years.3 Nationally representative research demonstrates that 95% of Americans do not consume enough Vitamin D from their diet alone,4 and approximately 40% of the US population, including children, adolescents, adults and the elderly, are suffering from either insufficient or deficient blood levels of vitamin D.5 A vitamin D supplement is an inexpensive, safe and effective way to ensure you are receiving adequate amounts of this important micronutrient.

Why is Vitamin D Important?

Immune Health

Vitamin D supports immune health by playing a crucial role in both acquired and innate immune responses.10,6† Vitamin D receptors are present in immune cells, therefore, adequate vitamin D is necessary for a healthy immune response in the body. This key vitamin supports the innate immune response, or the first line of defense in the body to combat foreign substances, also known as antigens. Vitamin D works to modulate various immune cells (e.g. dendritic cells) and proinflammatory cytokines (Interleukin-6, or IL-6) to support an appropriate immune response. Furthermore, vitamin D also supports the adaptive immune response (B cells, T cells, antibodies), which occurs not long after the innate immune response. In December 2020, over 200 scientists, doctors and leading authorities called for immediate widespread global increase in vitamin D intake.11,7 This call to action is addressed to governments, doctors, and healthcare workers to immediately recommend and implement the appropriate efforts to their adult populations to increase vitamin D. The recommendation is to achieve 25(OH)D serum levels over 30ng/ml (75nmol/L), a widely endorsed minimum blood concentration of vitamin D. From this, it has been suggested that adults consume a vitamin D intake of 4000 IU (100 mcg) daily, (or at least 2000 IU) in the absence of testing.

Bone Health Support

Vitamin D helps build and maintain strong bones and teeth by enhancing calcium absorption, regulating concentrations of calcium and phosphorus in the body, and regulating osteoclast (bone-resorbing cell) and osteoblast (bone-building cell) actions involved in bone remodeling.6-9 Vitamin D is mandatory for prevention of rickets and osteomalacia, and along with calcium, is associated with higher bone mineral density, lower osteoporosis risk, and reduction in fracture and fall risk.8,10

Muscle Health Support

Vitamin D is important for muscle health because it supports muscle function, muscle strength and balance.9,11†


Food Sources of Vitamin D

It is also important to point out that few foods naturally contain vitamin D; these include certain fatty fish (e.g. salmon, mackerel, sardines), fish liver oils, eggs, and UV-irradiated mushrooms. To prevent rickets, the US began fortifying our dairy and cereal with vitamin D in the early 20th century. Unfortunately, large amounts of these natural or fortified sources need to be consumed to meet vitamin D requirements. For example, 20 glasses of milk per day12 would need to be consumed to achieve the recommendation of 50 mcg (2,000 IU) of vitamin D, a daily recommended level associated with healthy vitamin D blood levels.13


Amount Per Serving12,14

Fortified milk

2.5 mcg (100 IU) per cup Fortified

Orange juice

2.5 mcg (100 IU) per cup Fortified


3.3 mcg (133 IU) per cup Cooked

Wild salmon

21.2 mcg (847 IU) per 3 oz Cooked

Farmed salmon

5.2 mcg (206 IU) per 3 oz


1.0 mcg (41 IU) per 1 whole egg


Useful Vitamin D Conversion:

1 mcg = 40 IU

1 ng/ml = 2.5 nmol/L


Did You Know That There Are Two Forms of Vitamin D?

Vitamin D is available in two forms: vitamin D2 (plant-derived) and vitamin D3 (animal-derived). Vitamin D3 is the preferred form because it has been shown to be more effective at raising and maintaining serum vitamin D levels in your body.15 Vitamin D3 is the form most commonly found in nutritional supplements; the D2 form is primarily found as a prescription.

How Much is Right for Me?

Pharmacokinetics research demonstrates that 2.5 mcg (100 IU) of vitamin D increases serum 25-hydroxyvitamin D [25(OH) D] levels by approximately 1 ng/ml.16 Although individual differences and one’s baseline status affect the response to supplementation, this “rule of thumb” is useful to estimate dosing for vitamin D supplementation regimens.

The Food and Nutrition Board at The National Academy of Sciences Dietary Reference Intakes (DRIs) for vitamin D,16 and the US Endocrine Society’s Clinical Practice Guidelines for vitamin D,13 are useful to understand population and individual vitamin D needs, respectively. The DRI for vitamin D for infants up to 12 months is 10 mcg (400 IU) per day. From age 1 to age 70, the DRI for vitamin D is 15 mcg (600 IU) per day, and for age 70+ the DRI is 20 mcg (800 IU) per day. However, these amounts fall below the Endocrine Society’s recommendation of 25 - 50 mcg (1000-2000 IU) daily for maintaining a blood serum vitamin D concentration >30 ng/mL.

Should I Get My Vitamin D Level Checked?

Yes. With the large proportion (95%) of the population not getting enough vitamin D from diet and more than two-thirds of women age 15-65 have insufficient or deficient levels of vitamin D19, it is recommended for individuals to get their blood level of vitamin D checked. A vitamin D blood test can help determine the most effective amount for vitamin D supplementation to achieve a blood level within the normal to optimal range.

Guidance for interpreting serum 25(OH)D levels13


< 20 ng/ml


21-29 ng/ml


≥ 30 ng/ml


Vitamin D Intake and Supplementation Recommendations13,17

Age Group

Minimum Requirement for Bone Health16

To Raise 25(OH)D Levels Consistently > 30 ng/ml12

To Correct Deficiency12

Infants (0-1 year)

10 mcg (400 IU)/day

At least 25 mcg (1,000 IU)/day

50 mcg (2,000 IU)/day or 1,250 mcg (50,000 IU)/week (for 6 weeks)

Children & Adolescents (1-18 years)

15 mcg (600 IU)/day

At least 25 mcg (1,000 IU)/day

50 mcg (2,000 IU)/day or 1,250 mcg (50,000 IU)/week (for 6 weeks)

Adults (19+ years)

15 mcg (600 IU) – 20 mcg (800 IU)/day

At least 37.5 mcg (1,500 IU) – 50 mcg (2,000 IU)/day

150 mcg (6,000 IU)/day or 1,250 mcg (50,000 IU)/week (for 8 weeks)


Are You At Risk For Vitamin D Insufficiency?

You may be at risk if you:

  • Do not take a daily multivitamin with vitamin D and/or a vitamin D supplement
  • Do not make vitamin D in your skin from UVB rays as efficiently, such as older adults and darkerskinned individuals
  • Have an increased need for vitamin D, such as overweight or obese individuals; older adults (Note: There is an association between higher body mass index (BMI) and an increased prevalence of nutrient shortfalls, which includes vitamin D.19 More research is needed to determine whether these inadequacies in nutrients are due to insufficient dietary intake, altered metabolic processes, or both.18)
  • Limit sun exposure: wear sunscreen; restrict indoor activity; live at higher latitude or in regions with a long winter season or air pollution
  • Have a malabsorption syndrome, liver disease, or renal disease
  • Take medications that interacts with vitamin D absorption or metabolism

Your doctor can arrange for a simple serum 25-hydroxyvitamin D blood test to determine your vitamin D status. Be proactive with your health and consider taking a daily vitamin D supplement as part of a healthy supplement regimen.

Safety of Vitamin D Supplementation

Individuals who are clinically diagnosed with a vitamin D deficiency may require higher doses of vitamin D.

The Food and Nutrition Board at The National Academies Dietary Reference Intake for Vitamin D initially established a ‘No Observed Adverse Effect Level’ (NOAEL) of 10,000 IU of vitamin D daily, meaning no association was found for harmful effects and intakes of 10,000 IU of Vitamin D daily.18

Should I Add a Vitamin D Supplement?

It’s important for patients to communicate with their healthcare professionals about any changes to their daily regimen including dietary supplements. Work together to understand personal nutrition needs as well as current dietary patterns to identify nutrient gaps. For those who are still unable to meet their nutrient needs from diet alone, it’s important to discuss the need to fill any potential nutrient gaps with dietary supplements, as a safe and effective way to ensure adequate intake of all essential nutrients.

About Nature Made®

Over the last 50 years, Nature Made has been a trusted leader in the wellness industry. They have helped pioneer quality standards for vitamin, mineral and herbal supplements, and remain dedicated to formulating products backed by science. Committed to Good Manufacturing Practices (GMPs), Nature Made’s quality extends to every aspect of our production, from purchasing high-quality raw materials to routine testing for purity and potency. In fact, they were the first national supplement brand to have a product verified by United States Pharmacopeia (USP), and it is the national supplement brand with the most products carrying the USP Verified Mark, verification that products meet stringent quality criteria for purity and potency. Nature Made is also the #1 Pharmacist Recommended Supplement Brand in 9 Categories**

These materials are intended for educational purposes only

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**Based on U.S. News & World Report – Pharmacy Times Survey, 2021

†These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease


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