What is the recommended dosage for Vitamin D?

General: 600-800 IU/day; Deficiency Correction: 4,000-5,000 IU/day (under medical supervision); Cardiovascular Support: 1,000-2,000 IU/day

What are the side effects of Vitamin D?

Potential side effects include: Hypercalcemia at very high doses (fatigue, nausea, kidney stones), Constipation, Generally very safe at recommended doses.

What is vitamin D and how may it relate to cardiovascular health?

Vitamin D is a fat-soluble vitamin with receptors in heart and vascular tissue. Observational studies consistently link vitamin D deficiency with increased cardiovascular risk. However, large RCTs including VITAL have not demonstrated that vitamin D supplementation reduces cardiovascular events in the general population.

What dosage of vitamin D has been studied for cardiovascular outcomes?

Clinical trials have used 1,000–4,000 IU of vitamin D3 per day for cardiovascular endpoints. The VITAL trial used 2,000 IU daily for over 5 years. Correcting deficiency (25-OH-D below 20 ng/mL) appears more important than supplementing adequate levels. Dosing should be guided by blood testing.

What are the potential side effects of vitamin D supplements?

Vitamin D is generally safe at recommended doses. Excessive intake can cause hypercalcemia, leading to nausea, kidney stones, and cardiac arrhythmias. Vitamin D may interact with certain heart medications including digoxin (hypercalcemia risk) and thiazide diuretics. Blood calcium levels should be monitored at high supplemental doses.

Vitamin D

vitamin

Also known as: Cholecalciferol (D3), Ergocalciferol (D2), Calciferol, Calcidiol

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About

Vitamin D binds to receptors on cardiomyocytes, vascular smooth muscle, and endothelial cells, regulating calcium handling and the renin-angiotensin-aldosterone system. Observational studies show deficiency (<20 ng/mL) is associated with 50-80% increased cardiovascular risk, though the VITAL trial (25,871 participants) found supplementation did not significantly reduce major cardiovascular events.

How It Works

Binds to vitamin D receptors (VDR) on cardiomyocytes, vascular smooth muscle, and endothelial cells regulating calcium handling and contractile function; modulates the renin-angiotensin-aldosterone system (RAAS) — deficiency upregulates renin contributing to hypertension; suppresses vascular inflammation via NF-kB inhibition; supports endothelial nitric oxide synthase (eNOS) expression.

Evidence For Conditions

Condition	Grade	Studies	Participants
High Blood Pressure (Hypertension)	C	20	30000	View →
Heart Failure	C	6	3000	View →

Side Effects

Hypercalcemia at very high doses (fatigue, nausea, kidney stones)
Constipation
Generally very safe at recommended doses

Drug & Supplement Interactions

Thiazide diuretics (may increase hypercalcemia risk)
Statins (theoretical interaction via CYP enzymes)
Corticosteroids (may reduce vitamin D absorption)
Weight loss medications (may reduce absorption of fat-soluble vitamins)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Folate (Vitamin B9) Niacin (Vitamin B3) Vitamin E Vitamin K2

Quick Facts

Dosage: General: 600-800 IU/day; Deficiency_Correction: 4,000-5,000 IU/day (under medical supervision); Cardiovascular_Support: 1,000-2,000 IU/day
Forms: capsule softgel liquid drops tablet gummy
Natural Sources: Sunlight (UVB synthesis), Fatty fish (salmon, mackerel), Egg yolks, Fortified milk, UV-exposed mushrooms
Upper Limit: 4,000 IU/day (100 mcg)
Best Time: With a meal containing fat for better absorption

Evidence Summary

High Blood Pressure (Hypertension) C

Heart Failure C

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.