I am a giant believer within the function of vitamin D in optimizing your well being. As famous in earlier articles, it has been proven to assist promote a various vary of capabilities, together with psychological well being, skeletal well being, and immune operate.
Nevertheless, there’s one matter about vitamin D that deserves extra consideration — toxicity. Simply as a deficiency will result in numerous well being issues, it is vital to take care of a correct stability as a result of an excessive amount of vitamin D can even trigger issues. This situation, in addition to different subjects, was explored by Reinhold Vieth, Ph.D., throughout a presentation on the College of Minnesota, which I’ll summarize under.
Vitamin D Metabolism Defined
Vieth begins his presentation, featured within the video above, by offering an outline of how vitamin D is produced and metabolized in your physique.
• Your pores and skin creates an early model of vitamin D — This precursor substance travels by means of your bloodstream to your liver, the place it’s transformed into 25-hydroxyvitamin D. When your physician asks for a vitamin D blood take a look at, that is the vitamin D measurement they’re searching for.1
• The kidneys assist synthesize vitamin D — To turn into totally energetic, 25-hydroxyvitamin D then travels to your kidneys, the place it’s transformed into 1,25-dihydroxyvitamin D, which works extra like a hormone.
This energetic kind helps your intestines take in calcium from the meals you eat. It additionally helps a secure surroundings in your physique by ensuring cells get what they should operate accurately. Your physique shops this nutrient in locations akin to your muscular tissues and fatty tissue.2
• A straightforward method to perceive how vitamin D is created — To color an image explaining this course of, visualize the movement of vitamin D as if it strikes by means of a number of buckets, each linked by holes that permit the vitamin drop to the subsequent step. The primary bucket is the shape made in your pores and skin. The second is the 25-hydroxyvitamin D in your liver. The third is the energetic 1,25-dihydroxyvitamin D produced in your kidneys.
The rationale correct vitamin D ranges matter is that this nutrient doesn’t act alone. It really works alongside calcium and different substances to maintain many elements of your physique wholesome. Two widespread signs of vitamin D deficiency embody fatigue and brittle bones. Nevertheless, an excessive amount of vitamin D additionally has its dangers.
Balancing Calcium with Vitamin D — Your Physique’s Tightrope Act
One other essential matter that Vieth discusses is the interplay between vitamin D and calcium. Basically, vitamin D boosts your capability to soak up calcium from meals.
• Vitamin D will increase the bioavailability of calcium — If you eat meals wealthy in calcium, akin to dairy merchandise, your intestines soak up extra of that mineral if there may be sufficient vitamin D out there. Along with supporting your bones, calcium is vital for muscle and nerve well being.
• Parathyroid hormone (PTH) additionally helps calcium administration — It acts as a messenger in your physique’s calcium system. When calcium ranges are low, PTH sends alerts to your bones to launch some calcium into your bloodstream. Vitamin D works alongside PTH by serving to your physique take in calcium from meals by means of your digestive system, which helps replenish your bones.3
In case your vitamin D degree is just too excessive, your blood calcium ranges turn into extreme, resulting in hypercalcemia. You may really feel thirstier, develop fatigue sooner, or sense that your digestive habits have modified. Though hypercalcemia is uncommon, it does happen if you happen to take massive doses of supplemental vitamin D regularly.4
Results of Vitamin D Overload
Whereas low ranges of vitamin D will not be good, mega-doses put additional stress in your system. In case you already get sufficient vitamin D from solar publicity and/or average supplementation, swallowing extra will not make you more healthy.
• Signs of extra vitamin D — In Vieth’s presentation, he tells the story of a 29-year-old man who was experiencing a variety of signs, akin to vomiting, elevated thirst, and acute renal failure. At first, docs identified him with gastroenteritis, saying he’ll finally really feel higher.
Nevertheless, the person needed to return, and now, docs took him significantly. They examined his blood, which contained 3.72 mmol/L of calcium (regular is 2.20 to 2.65 mmol/L), in addition to a whopping 1,555 nmol/L of vitamin D (regular is 20 to 80 nmol/L).5
• Fortified merchandise drastically enhance your vitamin D ranges — Finally, the person’s father needed to be admitted to the identical hospital for comparable signs. After investigating their consuming habits, Vieth famous that the daddy and son’s desk sugar was fortified with pure vitamin D, a couple of milligram per teaspoon. Finally, they made a full restoration when the fortified desk sugar was eliminated.6
Setting the Basis to Optimized Vitamin D Ranges
The takeaway is that extreme vitamin D consumption from meals or dietary supplements are simply as dangerous as having too little. So, it is vital to be aware of complement dosages and never exceed really helpful quantities.
• Exposing your pores and skin to pure daylight at applicable instances is one of the best strategy — Nevertheless, there are specific caveats you want to pay attention to, akin to your eating regimen, which is most certainly excessive in linoleic acid (LA). When ultraviolet gentle hits your pores and skin, it additionally interacts with LA that triggers inflammatory responses and DNA harm. Because of this, high-LA diets make you extra vulnerable to sunburn and pores and skin harm.
• Take a extra cautious strategy to solar publicity as you’re employed to purge LA out of your physique — I like to recommend avoiding high-intensity noon solar publicity till you have been off vegetable oils for at the very least six months.
As you step by step eradicate LA out of your physique — a course of that sometimes takes two to 3 years — your danger of sunburn and pores and skin most cancers declines. Nevertheless, after about six months, your pores and skin is normally higher protected in opposition to sunburn, permitting you to securely get pleasure from solar publicity round photo voltaic midday.
• Think about your pores and skin colour when optimizing your vitamin D — Melanin, answerable for pores and skin pigmentation, additionally acts as a pure sunscreen. Because of this when you have darker pores and skin, you may want extra time below the solar to generate the identical quantity of vitamin D as these with lighter complexions.
Further Pointers for Secure Solar Publicity
If you start getting common solar publicity, use this easy security take a look at: watch your pores and skin for the primary signal of pinkness, which is an early warning of sunburn. Cease solar publicity earlier than your pores and skin turns pink to forestall harm. This pinkness threshold helps you identify your secure publicity time.
Now, what if you have to spend time below the solar however have not fully eliminated LA out of your physique but? Listed below are some protecting methods I like to recommend:
• Take 12 milligrams of astaxanthin every day to boost your pores and skin’s UV resistance.
• Apply topical niacinamide (vitamin B3) cream earlier than solar publicity to guard in opposition to UV-induced DNA harm.
• Take a child aspirin 30 to 60 minutes earlier than solar publicity to assist forestall LA conversion to dangerous oxidized linoleic acid metabolites (OXLAMs).
• Use molecular hydrogen dietary supplements to fight oxidative stress.
Tips on how to Complement Vitamin D Correctly
Whereas most individuals would most likely profit from a vitamin D3 complement, it is vital to get your vitamin D degree examined earlier than you begin supplementing.
• You can not depend on blanket dosing suggestions — The essential issue right here is your blood degree, not the dose, because the dose you want relies on a number of particular person components, together with your baseline blood degree.
• The candy spot for harnessing the advantages of vitamin D — Analysis suggests the optimum degree for well being and illness prevention is between 60 ng/mL and 80 ng/mL, whereas the cutoff for sufficiency seems to be round 40 ng/mL. In Europe, the measurements you are searching for are 150 to 200 nmol/L and 100 nmol/L respectively.
I’ve revealed a complete vitamin D report through which I element vitamin D’s mechanisms of motion and the way to make sure optimum ranges. I like to recommend downloading and sharing that report with everybody you realize. A fast abstract of the important thing steps is as follows:
1. First, measure your vitamin D degree — As soon as you realize what your blood degree is, you’ll be able to assess the dose wanted to take care of or enhance your degree. In case you can not get sufficient vitamin D from the solar (you should use the DMinder app7 to see how a lot vitamin D your physique could make relying in your location and different particular person components), you then’ll want an oral complement.
2. Assess your individualized vitamin D dosage — To do this, you’ll be able to both use the chart under, or use GrassrootsHealth’s Vitamin D*calculator. To transform ng/mL into the European measurement (nmol/L), merely multiply the ng/mL measurement by 2.5. To calculate how a lot vitamin D you could be getting from common solar publicity along with your supplemental consumption, use the DMinder app.8

3. Retest in three to 6 months — Lastly, you may have to remeasure your vitamin D degree in three to 6 months, to guage how your solar publicity and/or complement dose is working for you.
Take Your Vitamin D With Magnesium and K2
It is strongly really helpful to take magnesium and K2 concomitant with oral vitamin D. Knowledge from practically 3,000 people reveal you want 244% extra oral vitamin D if you happen to’re not additionally taking magnesium and vitamin K2.9
What this implies in sensible phrases is that if you happen to take all three dietary supplements together, you want far much less oral vitamin D with a view to obtain a wholesome vitamin D degree.

Often Requested Questions (FAQs) About Vitamin D Toxicity
Q: Why is vitamin D vital for well being, and the way is it processed in my physique?
A: Vitamin D helps your psychological, skeletal, and immune well being. It’s produced within the pores and skin from solar publicity, then transformed within the liver to 25-hydroxyvitamin D, and at last activated within the kidneys as 1,25-dihydroxyvitamin D. This ultimate kind helps take in calcium and keep cell operate.
Q: Can I’ve an excessive amount of vitamin D? In that case, what are the dangers?
A: Sure, extreme vitamin D results in hypercalcemia (excessive blood calcium), inflicting signs like fatigue, thirst, digestive points, and even kidney failure. This happens with persistent supplementation or consuming fortified meals unknowingly.
Q: How does vitamin D work together with calcium and different vitamins?
A: Vitamin D enhances calcium absorption from meals, which is crucial for bone, muscle, and nerve well being. It really works with parathyroid hormone (PTH) to take care of calcium stability. Supplementing with magnesium and vitamin K2 can also be essential, as they assist vitamin D operate effectively and safely.
Q: What is the most secure manner for me to get vitamin D from daylight?
A: Expose your pores and skin to solar simply earlier than it turns pink to keep away from sunburn. In case your eating regimen is excessive in linoleic acid (from vegetable oils), it will increase solar sensitivity. Decreasing LA consumption over time and utilizing protecting methods (like astaxanthin or niacinamide) assist your pores and skin deal with UV publicity higher.
Q: How ought to I complement vitamin D accurately?
A: Begin by testing your blood ranges. The optimum vary is 60 to 80 ng/mL (150 to 200 nmol/L). Use instruments just like the DMinder app or GrassrootsHealth’s calculator to evaluate solar publicity and decide the correct complement dose. Retest each three to 6 months to regulate consumption as wanted.
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