Can vitamin D (Vit D) overdose cause gastrointestinal problems, specifically gastric issues?

From the Guidelines

Vitamin D overdose can cause gastrointestinal problems, including gastric issues, due to high calcium levels in the body. According to the espen micronutrient guideline published in Clinical Nutrition in 2022 1, vitamin D toxicity symptoms are mediated by high calcium levels and include hypercalcemia, hypercalciuria, dizziness, and renal failure. While the study does not specifically mention gastric issues, it implies that high calcium levels caused by vitamin D toxicity can lead to various health problems.

Some possible gastrointestinal symptoms that may occur due to vitamin D overdose include:

• Nausea
• Vomiting
• Abdominal pain
• Constipation
• Loss of appetite

These symptoms are likely caused by the increased calcium absorption in the intestines, which can irritate the digestive tract. The study notes that vitamin D toxicity is rare but can occur with true overdoses, deliberate or accidental, typically single doses of millions IU or daily doses of >10,000 or even 100,000 IU 1.

To avoid vitamin D overdose and related gastrointestinal problems, it is essential to follow the recommended daily allowance of 600-800 IU for adults. If you suspect vitamin D overdose, stop taking supplements immediately and consult a healthcare provider, who may recommend blood tests to check your vitamin D and calcium levels, and provide treatment to lower blood calcium levels if necessary.

From the Research

Vitamin D Overdose and Gastrointestinal Problems

• Vitamin D overdose can cause hypercalcemia, which may lead to gastrointestinal problems, including nausea, vomiting, and abdominal pain 2, 3, 4, 5, 6
• The pathophysiology of hypercalcemia from vitamin D intoxication results from the long-term effects of vitamin D storage in adipose tissue 3
• Symptoms of vitamin D toxicity include confusion, apathy, recurrent vomiting, abdominal pain, polyuria, polydipsia, and dehydration 6
• Gastric issues, such as constipation and colic, have been reported in cases of vitamin D overdose 4

Hypercalcemia and Gastrointestinal Symptoms

• Hypercalcemia can cause nausea, vomiting, dehydration, confusion, somnolence, and coma 2
• Mild hypercalcemia is usually asymptomatic, but may be associated with constitutional symptoms such as fatigue and constipation in approximately 20% of people 2
• Severe hypercalcemia is associated with nausea, vomiting, dehydration, confusion, somnolence, and coma 2

Treatment and Management

• Treatment of hypercalcemia due to vitamin D overdose typically involves hydration, intravenous bisphosphonates, and glucocorticoids 2, 3, 5
• In patients with kidney failure, denosumab and dialysis may be indicated 2
• The underlying cause of hypercalcemia should be identified and treated 2