What is accurate
Vitamin D is essential. It helps the body absorb calcium, supports bone health, and plays important roles in muscle function and the immune system.
Too much vitamin D can be harmful. Because it is fat-soluble, excessive supplementation over time can lead to vitamin D toxicity (hypervitaminosis D), which usually causes high blood calcium (hypercalcemia).
Symptoms of toxicity can include:
Excessive thirst
Frequent urination
Nausea and vomiting
Constipation
Fatigue and weakness
Confusion
Kidney stones or kidney damage in severe cases
Heart rhythm disturbances in rare, severe cases
What is exaggerated
The headline (“quietly saving your bones—or silently poisoning your kidneys”) is designed to create fear. Vitamin D toxicity is uncommon and almost never occurs from normal sun exposure or eating typical foods.
Most cases of toxicity result from taking very large doses of supplements for extended periods, often far above recommended amounts or because of manufacturing errors or medical mistakes.
The evidence-based advice

For most healthy adults:

The recommended daily intake is 600 IU (15 mcg) for adults up to age 70 and 800 IU (20 mcg) for adults over 70, although individual needs vary.
The generally accepted Tolerable Upper Intake Level for adults is 4,000 IU (100 mcg) per day unless a healthcare professional recommends a higher dose for a specific medical reason.
Higher doses (such as 5,000–10,000 IU daily or more) may be prescribed for vitamin D deficiency, but they should be monitored with blood tests.
Bottom line

Vitamin D is safe and beneficial when taken appropriately. Toxicity is rare, but it can occur with prolonged excessive supplementation. If you’re taking high-dose vitamin D or multiple supplements containing vitamin D, it’s a good idea to review your total intake with a healthcare professional and, if appropriate, have your blood vitamin D and calcium levels checked. The goal is to correct deficiency—not to maximize vitamin D levels beyond what the body needs.