{"ok":true,"entry":{"slug":"vitamin-d","kind":"supplement","name":"vitamin d","aliases":["vitamin d3","cholecalciferol","calciferol"],"brands_sg":["Kordel's","Caltrate"],"class":"vitamin","tags":["bone-joint","immune"],"use_for":"calcium absorption and bone health · low sun or low levels","use_after":"with a meal · fat in the gut raises absorption","use_duration":null,"take_with":"food with some fat · calcium combos may add side-effect risk","pros":["rda 600 iu (15 mcg) a day; 800 iu over 70","d3 raises blood levels more, and longer, than d2","low sun, dark skin, older age = listed risk groups"],"cons":["ul 4,000 iu (100 mcg) a day; excess is toxic","toxicity is almost always from supplements, not sun","excess → high calcium: nausea, weakness, kidney stones"],"dose_note":"rda is 600 iu (15 mcg) a day for adults to 70 and 800 iu (20 mcg) over 70; the ul is 4,000 iu (100 mcg) a day; hsa limit for general-adult health supplements in singapore is 1,000 iu a day; blood levels of 20 ng/ml (50 nmol/l) or more are sufficient for most people","dosage":{"ul":"4,000 IU (100 mcg)","unit":"IU","fda_dv":"20 mcg (800 IU)","rda_ai":"600 IU (15 mcg) adults 19–70 · 800 IU (20 mcg) over 70","ul_status":"established","population":"general adult","hsa_max_daily":"1,000 IU (0.025 mg)"},"ul_status":"established","sg_class":null,"cautions":["reduced kidney function or hyperparathyroidism — higher high-calcium risk if also on a thiazide; ask your doctor first","fat malabsorption (celiac, crohn's, liver disease) — absorption depends on absorbing fat","on a thiazide diuretic — combination may raise blood calcium; ask your doctor first"],"clashes":[{"src":["nih_ods_vitd"],"note":"cuts absorption from food and supplements","with":"orlistat (xenical, alli)"},{"src":["nih_ods_vitd"],"note":"high vitamin d intakes might reduce their potency","with":"statins (atorvastatin, lovastatin, simvastatin)"},{"src":["nih_ods_vitd"],"note":"reduce calcium absorption and impair vitamin d metabolism","with":"corticosteroids (prednisone)"},{"src":["nih_ods_vitd"],"note":"with vitamin d may raise blood calcium — older adults, kidney, hyperparathyroidism","with":"thiazide diuretics"}],"sources":[{"id":"nih_ods_vitd","url":"https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/","label":"NIH ODS — Vitamin D Fact Sheet for Health Professionals (updated Jun 27, 2025)","quote":"Vitamin D (also referred to as calciferol) is a fat-soluble vitamin … Vitamin D promotes calcium absorption in the gut and maintains adequate serum calcium and phosphate concentrations to enable normal bone mineralization … The concurrent presence of fat in the gut enhances vitamin D absorption, but some vitamin D is absorbed even without dietary fat … most evidence indicates that vitamin D3 increases serum 25(OH)D levels to a greater extent and maintains these higher levels longer than vitamin D2 … Levels of 50 nmol/L (20 ng/mL) or more are sufficient for most people … Vitamin D toxicity is almost always a result of excessive intakes of vitamin D through supplements … Experts do not believe that excessive sun exposure results in vitamin D toxicity … Taking calcium supplements in combination with vitamin D supplements may increase the risk of certain adverse effects … Excess amounts of vitamin D are toxic … Hypercalcemia, in turn, can lead to nausea, vomiting, muscle weakness, neuropsychiatric disturbances, pain, loss of appetite, dehydration, polyuria, excessive thirst, and kidney stones … The weight-loss drug orlistat (Xenical and alli), together with a reduced-fat diet, can reduce the absorption of vitamin D from food and supplements … high intakes of vitamin D, especially from supplements, might reduce the potency of atorvastatin (Lipitor), lovastatin (Altoprev and Mevacor), and simvastatin (FloLipid and Zocor) … Corticosteroid medications, such as prednisone … can reduce calcium absorption and impair vitamin D metabolism … The combination of these diuretics with vitamin D supplements (which increase intestinal calcium absorption) might lead to hypercalcemia, especially among older adults and individuals with compromised renal function or hyperparathyroidism","accessed":"2026-08-27"},{"id":"fda_dv","url":"https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels","label":"FDA — Daily Value on the Nutrition and Supplement Facts Labels, Reference Guide: Daily Values for Nutrients (content current as of 03/05/2024)","quote":"DVs are the recommended amounts of nutrients to consume or not to exceed each day … Vitamin D 20mcg","accessed":"2026-08-27"},{"id":"hsa_hs_guidelines","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA — Health Supplements Guidelines GL-CHPB-3-001 Rev. 020 (January 2026), s4.8, Table 4 Vitamins Limits + List of Health Claims","quote":"HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5 … Table 4: Vitamins Limits … Vitamin D 0.025mg (1000IU) … Help in the absorption and use of calcium and phosphorus • Vitamin D … Maintain/support bone health • Vitamin D, K","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:34.039038+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}