Is vitamin K3 synthetic? An in-depth look at menadione
                                
                                
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                                    4 min read                                
                            
                                According to the National Institutes of Health, vitamin K is a group of fat-soluble compounds, but not all are created equal. So, is vitamin K3 synthetic? Unlike the natural forms found in plants and fermented foods, vitamin K3, also known as menadione, is indeed a synthetic compound produced in a laboratory.