Today, recommendations for individual nutrients are overseen by the National Academies of Sciences, Engineering, and Medicine (referred to in this book as the National Academies). While these are official recommendations, the science behind them is sometimes still not entirely settled. In some cases, there isn’t enough research for anything more than an educated guess. And actual individual requirements are affected by lifestyle, overall diet, and genetics, which means that it’s impossible to pin down the exact nutrient requirements of any one person.
