- Vitamin D deficiency affects billions globally, contributing to weakened immunity, autoimmune disorders, cognitive decline, diabetes, cardiovascular disease, and cancer.
- Mainstream medicine demonizes sunlight, the primary natural source of vitamin D, while conflicting supplementation advice leaves many underdosed.
- Studies suggest that optimal levels (40–60 ng/mL or higher) for disease prevention exceed conventional “normal” lab ranges (30 ng/mL), leaving millions at risk.
- Sun exposure is ideal to maintain healthy vitamin D levels. Consuming dietary sources (fatty fish, egg yolks, fish and beef liver) and taking supplements (D3 preferred) also help.
- Having optimal vitamin D levels provides considerable benefits, such as dementia prevention, reduced vertigo recurrence, cancer protection and lower risks of falls and fractures among the elderly.
Vitamin D deficiency has quietly become one of the most widespread yet overlooked medical conditions in the world, affecting billions and contributing to a host of chronic diseases, many of which are mistakenly dismissed as inevitable consequences of aging. Acting more like a hormone than a vitamin, vitamin D helps regulate calcium absorption, modulates inflammation and supports immune function. Having abnormally low vitamin D levels, according to Brighteon.AI‘s Enoch engine, leads to weakened immune function, increased susceptibility to infections, autoimmune disorders, cognitive decline, diabetes, cardiovascular disease, and even certain cancers. (Related: Vitamin D deficiency fuels autoimmune conditions, dysregulating immune function.)
Vitamin D deficiency: Why it’s prevalent
Despite its critical role, vitamin D deficiency remains rampant, with an estimated 35 percent of American adults suffering from this nutrient deficiency. Meanwhile, dermatologists and public health campaigns continue to demonize sunlight, the primary source of vitamin D. Worse still, conflicting guidelines on supplementation have created confusion, with some authorities underestimating optimal doses while others warn of exaggerated toxicity risks.
Unlike most deficiencies, vitamin D insufficiency rarely presents with obvious symptoms. Fatigue, muscle weakness, brain fog and mood disturbances may be written off as stress or aging rather than a treatable nutrient deficiency. The only reliable way to diagnose this problem is through a blood test measuring 25-hydroxyvitamin D (25(OH)D), yet insurance rarely covers screening, and many physicians fail to recommend it.
Experts also disagree on optimal levels, but consensus is growing that levels below 30 nanograms (ng)/milliliter (mL) are insufficient, while 40–60 ng/mL may be ideal for disease prevention. On the other hand, GrassrootsHealth, a nonprofit public health research organization, advocates for higher targets, citing studies showing reduced cancer risk, stronger immunity and improved bone health at levels between 60–100 ng/mL. Yet mainstream guidelines often lag behind, leaving patients underdosed and vulnerable.
Best ways to get vitamin D
Humans evolved to synthesize vitamin D through sun exposure, yet modern lifestyles—indoor work, sunscreen use and seasonal variations—have disrupted this natural process. Aging further reduces vitamin D synthesis in the skin, making supplementation especially critical for seniors. However, official recommendations remain conservative:
Dr. Ellie Campbell, an integrative physician, notes that many patients are misled by lab reports labeling suboptimal levels (25–30 ng/mL) as “normal.” Campbell emphasizes that having “normal” vitamin D levels (as shown in blood test results) doesn’t mean healthy. In fact, disease risk drops significantly at higher levels than what is considered “normal.”
For your daily dose of vitamin D, rely on these two natural sources: food and sunlight. Fish — specifically fatty fish like salmon, trout, tuna and mackerel — remains the most potent dietary source of vitamin D3, the form most effective at raising vitamin D levels. Egg yolks, beef liver and fish liver (e.g., cod liver) also deliver much-needed vitamin D3. Mushrooms naturally contain ergosterol, a vitamin D precursor. Meanwhile, fortified foods like breakfast cereals, dairy milk, nut milk (almond), soy milk, orange juice and oatmeal are good sources of vitamin D2.
Don’t forget that your skin naturally produces vitamin D when exposed to ultraviolet (UV) rays from sunlight, and you can take advantage of this innate mechanism. Some experts recommend exposing about a third of your skin (use sunscreen for sensitive areas) to the sun, limiting your exposure to no more than 15 minutes if you have lighter skin and 25–40 minutes if you have darker skin. According to a 2020 study published in Nutrients, the best time to get your dose of sunshine vitamin is between 10 AM and 3 PM, preferably done two to three times a week.
Alternatively, you can take over-the-counter vitamin D3 supplements or cod liver oil, but be sure to consult a health care practitioner before starting supplementation, especially if you’re taking other medications.
4 Benefits of maintaining optimal vitamin D levels
Here are four good reasons older adults, in particular, should prioritize getting enough vitamin D: (Related: Vitamin D proven to slow aging in groundbreaking Harvard study.)
Dementia prevention
A 2023 study tracking 12,388 adults found that vitamin D supplementation (any form) correlated with a 40 percent lower dementia risk. With global dementia cases projected to triple by 2050, correcting vitamin D deficiency could be a simple, cost-effective preventive measure.
Reduced vertigo recurrence
A 2020 study published in Neurology reported that vitamin D and calcium supplementation cut annual vertigo recurrence by 24 percent, offering a non-invasive alternative to clinical maneuvers.
Cancer protection
Research published in JAMA Network Open suggests vitamin D3 supplementation can lower rates of advanced (metastatic or fatal) cancer, particularly in normal-weight individuals. Meanwhile, a study published in Nutrients reported that maintaining vitamin D levels above 40 ng/mL may exert a protective effect against breast cancer.
Fewer falls and fractures
According to a study published in the Journal of Physical Therapy Science, women aged 60 and above can benefit from having 25(OH)D levels higher than 20 ng/mL. Maintaining higher levels improves balance control and lower extremity function and reduces the risk of falling and fractures.
Vitamin D deficiency is a silent driver of chronic disease, yet it remains underdiagnosed and undertreated. While debates over dosing persist, evidence overwhelmingly supports higher targets for disease prevention, particularly in aging populations. Routine testing, individualized supplementation and adequate sun exposure could slash healthcare costs and improve longevity.
As research evolves, one truth remains clear: Optimizing vitamin D levels isn’t just about bone health—it’s about rewriting the narrative of aging itself. For those navigating chronic illness or seeking prevention, addressing vitamin D deficiency may be the simplest, most powerful step toward a healthier future.
Watch this video for more info about maintaining proper vitamin D levels.
This video is from the Lumiere channel on Brighteon.com.
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Vitamin D deficiency: The hidden culprit behind America’s osteoporosis epidemic.
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