The Endocrine Society's Vitamin D Guidelines: A Step Backward?
I recently came across an update from the Endocrine Society regarding vitamin D as part of my continuing medical education. While I had hoped for an insightful, evidence-based discussion on its role in metabolism, immunity, and endocrine function, what I found instead was a stark example of how conventional medical guidelines can sometimes diverge from the physiological reality of human health.
WHAT DID THE ENDOCRINE SOCIETY SAY?
In June 2024, the Endocrine Society released new recommendations stating that empiric vitamin D supplementation (providing vitamin D without testing levels first) is no longer necessary for most adults. They also downplayed the need for routine vitamin D testing, arguing that widespread deficiency is overstated and that supplementation beyond the daily recommended allowance (600-800 IU) is unlikely to provide additional benefits for individuals under 75 years old.
Essentially, their stance is:
Vitamin D deficiency isn’t as big of a problem as we thought.
Supplementing without testing is unnecessary.
Vitamin D’s primary role is in bone health, and its benefits beyond that are inconclusive.
WAIT… WHAT?!
This completely ignores decades of research showing that vitamin D plays a critical role in insulin regulation, immune function, brain health, and hormone balance. In fact, vitamin D is not just a vitamin—it acts as a steroid hormone precursor, regulating over 200 genes.
So why would the Endocrine Society—the very group that should be leading the charge in understanding the hormonal impact of vitamin D—suddenly minimize its importance? Let’s break it down.
THE CLINICAL TRIAL CONUNDRUM: WHY “NO EVIDENCE” DOESN’T MEAN “NO BENEFIT”
Many of the large clinical trials they cite as “proof” that vitamin D supplementation isn’t useful were designed poorly:
Low doses: Many studies gave participants only 400-2000 IU/day, which is often too little to correct a deficiency.
No baseline testing: Some trials included people who already had adequate vitamin D levels, skewing the results.
Lack of synergy: Vitamin D doesn’t work alone—it interacts with magnesium, vitamin K2, and omega-3s, but studies rarely account for these cofactors.
Dismissing vitamin D’s benefits just because these studies didn’t show a statistically significant effect is like saying exercise isn’t important because some trials didn’t prove it prevents heart disease in all populations.
OVERCORRECTING FOR THE “VITAMIN D BOOM”
A decade ago, vitamin D was hailed as the miracle nutrient, with many doctors prescribing high doses without testing. Some people were taking 50,000 IU weekly without considering their actual needs, which raised concerns about calcium buildup and hypervitaminosis D.
Now, perhaps, in an attempt to avoid overprescribing, the Endocrine Society has swung too far in the other direction, claiming that most people don’t need to worry about it at all.
But overuse doesn’t mean no use. Just because some people were taking unnecessarily high doses doesn’t mean that deficiency isn’t a real and widespread problem.
THE BONE-CENTRIC BLIND SPOT
Old-school medical thinking treats vitamin D as if its only job is preventing rickets. But we now know that vitamin D is critical for:
Insulin sensitivity – Low vitamin D is associated with higher fasting glucose and insulin resistance.
Immune function – Vitamin D modulates the immune system, helping prevent autoimmunity and infections.
Mental health – Low vitamin D levels correlate with depression, anxiety, and cognitive decline.
Hormonal regulation – The ovaries, testes, and adrenal glands all have vitamin D receptors, impacting fertility, testosterone levels, and adrenal function.
By limiting the discussion to bone health, the Endocrine Society is failing to acknowledge the bigger picture.
SYMPTOMS OF VITAMIN D DEFICIENCY
If vitamin D deficiency were truly uncommon, we wouldn’t see so many people experiencing improvements when they supplement. Some of the most common symptoms of vitamin D deficiency include:
Fatigue and low energy – Vitamin D is essential for mitochondrial function and energy production.
Joint pain and muscle weakness – It plays a role in reducing inflammation and supporting musculoskeletal health.
Increased pain sensitivity – Research suggests that vitamin D helps regulate pain perception, and low levels may contribute to chronic pain conditions.
Frequent colds or infections – Vitamin D is crucial for immune function and helps modulate inflammation.
Mood changes, anxiety, or depression – Vitamin D receptors are found in the brain, and deficiency is linked to increased risk of mood disorders.
Slow wound healing – Vitamin D supports cellular repair and immune function, both of which are necessary for proper healing.
If any of these sound familiar, checking your vitamin D levels and supplementing accordingly can be a game-changer.
WHO BENEFITS FROM DOWNPLAYING VITAMIN D?
We have to ask: Who gains from discouraging vitamin D supplementation?
Pharmaceutical companies? If fewer people supplement, more will develop metabolic and inflammatory conditions that require medication.
Insurance companies? Routine vitamin D testing is no longer being encouraged, saving them money.
Medical institutions stuck in outdated models? Conventional medicine often resists functional and integrative approaches, even when they align with physiological research.
Regardless of the motive, this recommendation does a disservice to patients.
SO, WHAT SHOULD YOU DO?
Despite these new guidelines, functional medicine continues to emphasize the importance of vitamin D optimization. Here’s what I recommend:
Test, don’t guess – If possible, get your 25-hydroxyvitamin D levels checked before supplementing.
Aim for functional levels – While conventional medicine considers 20 ng/mL “sufficient,” functional medicine recommends 50-70 ng/mL for optimal health.
Prioritize quality sources – Sun exposure, vitamin D-rich foods (like fatty fish and egg yolks), and supplementation when needed.
Support synergy – Take magnesium and vitamin K2 alongside vitamin D for better absorption and function.
Dose smart - If you are suboptimal, consider dosages between 2000-6000IU daily until you’re between 50-70 ng/mL. You don’t need to megadose to raise your levels.
FINAL THOUGHTS: THE REALITY OF VITAMIN D DEFICIENCY
The Endocrine Society’s new stance is disappointing but not surprising. It reflects a broader issue in conventional medicine—if something isn’t proven in a large RCT, it’s dismissed, even when fundamental physiology says otherwise.
But here’s the truth: Vitamin D is essential, deficiency is real, and optimizing it can make a profound difference in your metabolic, immune, and endocrine health. Don’t let these new “guidelines” dictate your well-being—trust the science and your own body.
What are your thoughts on this shift? Have you personally noticed a difference from optimizing your vitamin D levels? Let me know in the comments!
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