one can get vit d toxicity. it is good to test levels from time to time when taking regular high doses. dr mercola discusses a mailin test on his site. also dont forget vit k which helps with absorption of vit d. our bodies are used to consuming vit d (not through skin) from animal products high in fat and vit k like fish, butter, eggs, fatty meats from pastured animals. weston price is authority on this.