VEGANALYZE

Vitamin D Overdose And Toxicity

Vitamin D overdose and excess are extremely rare 1.

However, prolonged exposure to sunlight does not negatively affect vitamin D levels and does not have any side effects 2. Additionally, consuming too many Vitamin D-rich foods does not lead to an overdose.

Cause

A vitamin D poisoning is one of the rarest conditions caused by accidental or intentional consumption of extremely high doses (e.g., over 10,000 IU per day) of vitamin D supplements over an extended period (several months) 3 4.

Other causes may include increased fortification of milk with vitamin D, foods heavily fortified with vitamin D, and premature infant formula 5 6 7 8.

Symptoms

Symptoms of vitamin D overdose are non-specific and primarily occur due to high levels of calcium in the blood. These symptoms include, among others, 9 10 11:

• Abdominal pain
• Constipation
• Nausea / vomiting
• Joint pain
• Loss of appetite
• Headaches
• Confusion
• Depression
• Muscle weakness
• Fatigue
• High blood pressure
• Polyuria (increased urination)
• Polydipsia (increased thirst)

Since vitamin D is stored in the body, the symptoms and consequences can persist for several months.

Consequences

An excessive intake of vitamin D increases circulating 25-hydroxyvitamin D (abbreviated as 25(OH)D). High levels of circulating vitamin D are characterized by an increased accumulation of calcium (hypercalcemia) and phosphate (hyperphosphatemia) in the blood, increased calcium absorption from food, and higher excretion of calcium (hypercalciuria) 12. Additionally, bone density worsens but normalizes after discontinuation of supplement use 13.

Consequences can include deposits (nephrocalcinosis) and accumulation (calcification) of calcium and phosphate in the heart, kidneys, and lungs, leading to narrowing of the organ's blood vessels and the formation of kidney stones 14. In severe cases, it can lead to kidney failure and cardiac arrest 15.

Some dietary supplements may contain more vitamin D than indicated on the label. 16 17. According to scientists, vitamin D overdose-induced hypercalcemia can also be an underlying cause of life-threatening complications.

Maximum Daily Limits

The following values have been defined by the Institute of Medicine, Food and Nutrition Board (FNE) as maximum daily limits to avoid vitamin D poisoning 18:

Conversion: 1 µg = 40 IU and 1 IU = 0.025 µg

Detecting Vitamin D Overdose

A vitamin D toxicity is determined by high vitamin D plasma levels [25(OH)D], high plasma calcium concentrations, and normal parathyroid hormone levels. 19.

If the 25(OH)D levels exceed 150 ng/mL (approximately 374 nmol/L), it is considered a vitamin D toxicity. 20. The following table provides information on optimal and elevated vitamin D levels. 21:

Conversion: 1.0 ng/ml = 2.5 nmol/l

However, there is evidence that the initial health damage may occur at plasma levels of 50 ng/ml (125 nmol/l) 22.

Additional tests that can be performed to confirm vitamin D overdose include: determining plasma levels of phosphorus and taking and evaluating X-rays of the bones 23.

Studies on dosage amounts

Dosages exceeding 250 μg (10,000 IU) per day are generally associated with an increase in plasma levels above 150 ng/ml, which can lead to health damage 24. Many studies indicate that there is no risk of side effects associated with long-term intake of 250 μg (10,000 IU) of vitamin D3 per day 25.

Other scientists speak of vitamin D toxicity with 25(OH)D > 200 ng/mL, which can be achieved with doses of 40,000 IU per day over an extended period 26 27 28. On the other hand, other studies have shown that doses of 50,000 IU over a period of 1 to 5 months did not result in any negative effects such as hypercalcemia or hypercalciuria 29.

Among pregnant women who took 4,000 IU of vitamin D per day starting from the 12th week of pregnancy, there were no changes observed in plasma calcium concentrations or urinary calcium excretion. 30.

In the case of infants, a serum 25(OH)D level greater than 100 ng/mL is considered indicative of hypervitaminosis D. 31. According to the study, a toddler experienced hypervitaminosis D with serum 25(OH)D concentrations exceeding 400 ng/mL after taking 240,000 IU of vitamin D3 (12,000 IU daily for 20 days), but without any signs of vitamin D toxicity.

Treatment

Often, it is sufficient to remove all sources of vitamin D and increase fluid intake to bring elevated plasma calcium concentrations back to a normal level in a relatively short period of time and without sequelae. 32.

Other treatment options include administration (both intravenous and oral) of bisphosphonates, calcitonin, glucocorticoids, and diuretics (promote water excretion). 33 34 35. A patient who was poisoned by excessive dosages from dietary supplements was treated with saline solutions, furosemide, and disodium pamidronate. 36.