Why Does Calcium Always Come with Vitamin D?
                                
                                
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                                    4 min read                                
                            
                                According to the National Institutes of Health, vitamin D significantly increases the amount of dietary calcium your body can absorb from 10–15% to 30–40%. This symbiotic relationship is the primary reason why calcium always comes with vitamin D in supplements and fortified foods, as one is rendered largely ineffective without the other.