What is the recommended dosage for Vitamin D?

General: 600-2,000 IU/day; Deficiency Correction: 4,000-5,000 IU/day

What are the side effects of Vitamin D?

Potential side effects include: Hypercalcemia at very high doses, Nausea and vomiting, Kidney stones (rare, high doses), Weakness and fatigue.

Vitamin D is a fat-soluble vitamin and neurosteroid hormone that plays a role in brain development and function. Vitamin D receptors are widely distributed throughout the brain. Research has associated low vitamin D status with increased risk of cognitive concerns, particularly in older adults.

What dosage of Vitamin D has been used in cognitive studies?

Cognitive studies have used 800 IU to 4,000 IU of vitamin D3 (cholecalciferol) daily. Some studies have targeted specific serum 25(OH)D levels, typically above 30 ng/mL. The tolerable upper intake is 4,000 IU per day for adults. Consult your healthcare provider and consider testing your levels.

What are the potential side effects of Vitamin D?

Vitamin D toxicity is rare but can occur with prolonged intake above 10,000 IU per day, causing hypercalcemia with symptoms including nausea, weakness, and kidney problems. Vitamin D may interact with certain heart and kidney medications. Consult your healthcare provider for appropriate dosing.

Vitamin D

vitamin

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

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About

Vitamin D is a neurosteroid hormone with receptors throughout the brain, particularly in the hippocampus and cerebral cortex. Deficiency, which affects 40% of geriatric memory clinic patients, is identified as a critical risk factor for cognitive decline. Supplementation supports calcium signaling in neurons, neurotrophic factor expression, and protection against oxidative stress and inflammation.

How It Works

Neurosteroid hormone with receptors in the hippocampus and cerebral cortex; supports calcium signaling in neurons, neurotrophic factor expression, neurotransmitter synthesis, and neuronal protection against oxidative stress and inflammation.

Evidence For Conditions

Condition	Grade	Studies	Participants
Nutritional Deficiency Cognitive Impairment	B	20	4500	View →
Depression-Related Cognitive Dysfunction	C	12	2000	View →

Side Effects

Hypercalcemia at very high doses
Nausea and vomiting
Kidney stones (rare, high doses)
Weakness and fatigue

Drug & Supplement Interactions

Corticosteroids (reduce calcium absorption)
Statins (both affect cholesterol pathways)
Thiazide diuretics (additive calcium retention)
Weight loss drugs (may reduce vitamin D absorption)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Folate Niacin Vitamin B12 Vitamin B6 Vitamin E

Quick Facts

Dosage: General: 600-2,000 IU/day; Deficiency_Correction: 4,000-5,000 IU/day
Forms: softgel capsule tablet drops gummy
Natural Sources: Sunlight, Fatty fish, Fortified milk, Egg yolks, Mushrooms
Upper Limit: 4,000 IU/day (IOM); 10,000 IU/day (Endocrine Society upper safety)
Best Time: With meals containing fat; morning preferred

Evidence Summary

Nutritional Deficiency Cognitive Impairment B

Depression-Related Cognitive Dysfunction 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.