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Niacinamide ： UV Protection (Internal Photoprotection)

A

The ONTRAC trial (NEJM 2015) found oral nicotinamide 500 mg twice daily reduced new nonmelanoma skin cancers by 23% and actinic keratoses by 11% in high-risk individuals, supporting cellular DNA repair via NAD+ replenishment.

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結論

            
            
The ONTRAC trial (NEJM 2015) found oral nicotinamide 500 mg twice daily reduced new nonmelanoma skin cancers by 23% and actinic keratoses by 11% in high-risk individuals, supporting cellular DNA repair via NAD+ replenishment.

            
            
        

    











    
    

        
        

            

  
Key Statistics





            


    

        
5

        
研究数

    

    

        
686

        
参加者数

    

    

        
            
            ↑
            
        
        
Positive

    

    

        A

        
グレード

    




        


        
        

        
        
        

            

  
Dosage & Usage





            
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units


            
            

                
一般的な使用量

                

                    
                    

                        
general:

                        
14-16 mg/day NE (RDA)

                    

                    
                    

                        
skinhealth:

                        
500-1,500 mg/day oral nicotinamide

                    

                    
                

                
                

                    上限量： 35 mg/day for niacin (flushing form); nicotinamide well-tolerated up to 3,000 mg/day
                

                
            

            

            

            
            

                推奨摂取タイミング： With meals; can be split into 2-3 doses
            

            
        

        

        
        
        

            

  
Safety & Side Effects





            

                
                

                    
報告されている副作用

                    
    
                        
                        
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                            Generally well-tolerated (no flushing unlike niacin)
                        
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                            Mild gastrointestinal discomfort at high doses
                        
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                            Rare hepatotoxicity at very high doses (> 3,000 mg/day)
                        
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既知の相互作用

                    
    
                        
                        
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                            ●
                            Anticonvulsants (carbamazepine — may increase niacinamide levels)
                        
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                            Hepatotoxic drugs (potential additive liver effect at high doses)
                        
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                            Isoniazid (competes for NAD+ pathways)
                        
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                        耐容上限摂取量： 35 mg/day for niacin (flushing form); nicotinamide well-tolerated up to 3,000 mg/day
                    

                

                
            

            

                サプリメントの摂取を開始する前に、必ず医療専門家にご相談ください。
            

        

        

        
        
        

            

  
Frequently Asked Questions





            




    
    

        
            Does Niacinamide help with UV Protection (Internal Photoprotection)?
            
        
        

            Based on 5 studies with 686 participants, there is strong evidence from multiple clinical trials that Niacinamide may support UV Protection (Internal Photoprotection) management. Our evidence grade is A (Strong Evidence).
        

    

    
    

        
            How much Niacinamide should I take for UV Protection (Internal Photoprotection)?
            
        
        

            Studies have used various dosages. A commonly studied range is 14-16 mg/day NE (RDA). Always consult your healthcare provider before starting any supplement regimen.
        

    

    
    

        
            Are there side effects of Niacinamide?
            
        
        

            Reported side effects may include Generally well-tolerated (no flushing unlike niacin), Mild gastrointestinal discomfort at high doses, Rare hepatotoxicity at very high doses (> 3,000 mg/day). Most side effects are mild and dose-dependent. Consult your doctor if you experience any adverse reactions.
        

    

    
    

        
            How strong is the evidence for Niacinamide and UV Protection (Internal Photoprotection)?
            
        
        

            We rate the evidence as Grade A (Strong Evidence). This rating is based on 5 peer-reviewed studies with 686 total participants. The overall direction of effect is positive.
        

    

    




        

        

        
        
        

            

  
Related Evidence





            

                
                
                

                
                

                    
Niacinamide 他の症状・状態について

                    

                        
                        
                            Acne
                            A

                        
                        
                    

                

                
            

        

        

    


    
    












    

        FDAに関する免責事項:
        これらの記述は米国食品医薬品局（FDA）による評価を受けていません。本ウェブサイトの製品および情報は、疾病の診断、治療、治癒、または予防を目的としたものではありません。表示されているエビデンスグレードは、公開された査読済み研究の分析に基づいており、医療上の助言を構成するものではありません。サプリメントの摂取を開始する前に、必ず医療専門家にご相談ください。