July 21, 2025 Puzzle Piece
Signs and Side Effects of Vitamin D Deficiency and Overdose
Vitamin
D plays an important role in maintaining overall health. It’s
necessary for the growth and development of muscle cells, proper
functioning of the innate and adaptive immune system, maintenance of the
health of the skeletal system, and as a pro-hormone, etc. Therefore,
insufficient, or deficient levels of vitamin D may increase risk of
disease and infection, bone demineralization, poor wound healing, and
many other negative health outcomes. Many articles are written on
deficiency, but few point out too much can be too much.
A very conservative estimate is there is a vitamin D deficiency or
insufficiency in 50% of U.S. adults. It is safe to say the entire world
population is vitamin D deficient as well. Factors that increase the
risk of vitamin D deficiency include:
- skin color
- where you live
- your ability to absorb vitamin D
- sun exposure
- medical conditions
- body weight
- nutrient and supplement intake
Because
vitamin D insufficiency and deficiency are common, many people use
vitamin D supplements to maintain healthy vitamin D levels. Although
uncommon, vitamin D toxicity (hypervitaminosis D, vitamin D
intoxication) can occur from accidental overdose, prescription errors in
writing or interpreting and misuse of high-dose vitamin D supplements.
Vitamin D toxicity is more common in people with certain medical
conditions. These include:
- granulomatous disorders
- congenital disorders
- some lymphomas
- dysregulated vitamin D metabolism
- taking vitamin D daily without testing (to not test, is to not know!)
The only way to know your D status is to have periodic blood tests
to monitor levels. The accepted levels are 30 – 100 ng/mL. I like
mine near the 90-100 level. I tested mine last week and it was 92. At
one point I supplemented without testing for over a year and had levels
at 112. Please test yourself and your patients at least once a year.
Elevated blood levels for vitamin D to reach toxic or
dangerous levels in the body, needs to exceed 100 nanograms (ng) per
mL. Hypervitaminosis D is defined at serum levels of over 150mg/mL.
Recommendations on optimal vitamin D levels vary, but research suggests
that levels between 30–60 ng/mL are likely optimal from mainstream
thinking and may help protect against illness and disease.
In a 2020 case report, a 56-year-old woman who took an average of
130,000 IU of vitamin D per day for 20 months in hopes of improving
symptoms of multiple sclerosis was hospitalized for symptoms including
nausea, vomiting, and muscle weakness. Her vitamin D levels were
discovered to be 265 ng/mL. Note that 130,000 IU is over 30 times the
generally recommended safe upper limit of 4,000 IU per day.
Even though toxicity is unlikely if you keep your daily intake levels
below 10,000 IU per day and avoid excessively high intakes of vitamin D
supplements, experts recommend that people with typical vitamin D levels
do not exceed 4,000 IU of vitamin D per day. If you do not test, you
do not know where your levels are. People who are low or deficient in
vitamin D typically need to take much higher levels than the current
Tolerable Upper Intake Level (UL) of 4,000 IU per day to reach and maintain optimal vitamin D levels.
Vitamin D levels greater than 100 ng/mL may be harmful. Toxicity
symptoms have been reported at extremely high blood levels in cases
where people took megadoses of vitamin D supplements for extended
periods of time. I TAKE 2 DAK1K2 EVERY DAY. You can take this
formulation all at once in the day as Vitamin D is fat soluble and
therefor taking 2 at one time will allow the formula to be released
evenly throughout the day and night. In contrast to Vitamin C, which is
water soluble. If you take too much C as one time, you will pass it
out through the urine.
Elevated blood calcium levels
Vitamin D helps your body absorb calcium from the food you eat. In fact,
this is one of its most important roles. However, if your vitamin D
intake is excessive, your blood calcium may reach levels that can cause
unpleasant and potentially dangerous symptoms. The symptoms of vitamin D
toxicity are primarily related to hypercalcemia (excessively high blood
calcium levels). Symptoms of hypercalcemia include:
- digestive distress, such as vomiting, nausea, constipation, and stomach pain
- fatigue, dizziness, hallucinations, and confusion
- loss of appetite
- excessive urination
- kidney stones, kidney injury, and even kidney failure
- high blood pressure and heart abnormalities
- dehydration
The
normal range of blood calcium is 8.5–10.8 mg/dL. Hypercalcemia
typically develops after people take large doses of vitamin D for a
prolonged period. Hypercalcemia can be life threatening and requires
immediate medical attention. Hypercalcemia can lead to altered mental
status in people with vitamin D toxicity. People with vitamin D
toxicity–induced hypercalcemia commonly have symptoms like confusion,
depression, agitation, unresponsiveness, and psychosis. In extreme
cases, coma has been reported.
In a 2021 case report, a 64-year-old man accidentally took 200,000 IU of
vitamin D per day because he misunderstood medication instructions. He
showed altered mental status and other serious symptoms related to
hypercalcemia. He remained agitated and confused for the first 10 days
of his stay in the hospital, but his symptoms gradually improved as his
calcium levels dropped. It took about 18 days for his calcium to return
to expected levels.
In some cases, vitamin D toxicity can result in kidney injury and
even kidney failure. This is because having too much vitamin D in the
body can lead to high levels of calcium, which can lead to water loss
through too much urination and calcification of the kidneys.
Hypercalcemia can also cause the blood vessels of the kidneys to
constrict, which leads to decreased kidney function.
Many studies have reported moderate-to-severe kidney injury in people who develop vitamin D toxicity. Interestingly, a vitamin D deficiency
can also harm the kidneys and lead to severe complications in those
with kidney disease. That’s one reason why maintaining optimal blood
levels of vitamin D is critical. Deficiency is much more common. In
fact, estimates suggest that about 1 billion people worldwide are
deficient in vitamin D.
To repeat, the only way to tell if you’re insufficient, deficient, or in
excess is to have a healthcare professional test your vitamin D levels
at least once to twice per year.
Our favorite Vitamin D is Dr Harris’s OHS DAK1K2, which
as all the factors for absorption and proper calcium distribution and
utilization throughout the body. To repeat, I take 2 in the morning every day!
Yours in Health and Wellness,
John W Brimhall, DC, BA, BS, FIAMA, DIBAK, Formulator, Patent Holder
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