"The earliest documented examples of micronutrients’ influencing immunity date from the nineteenth century. Such work indicated previously unappreciated links with immunity and made a strong case that infections did not cause observed disorders and pathologies but were secondary to deficiency in micronutrients. Supported by clinical and epidemiological studies, which show a substantial negative correlation of nutritional deficiencies with immunocompetence and the reverse correlation with the risk of infection and related pathologies, is the idea that nutrition is an important determinant of immunity is now generally well accepted (Fig. 1). Nevertheless, the impact of dietary elements in immune system–related processes is still often dismissed, even when substantial amounts of data correlate diet with immune system–related related disorders."