Intellectual disability (ID) is a condition that affects approximately 1% of the population (Mauliket al, 2011). The numbers may differ across nations, owing to different systems and diagnosis entries or lack of such, but usually range between 0.6 and 3% (Stromme & Valvatne, 1998). Persons withIDare a heterogeneous group with different diagnoses and different levels of intellectual ability. These range from profound (IQ < 20) and serious ID(IQ20-34) to moderate (IQ35-49) and lightID(IQ50-69); this roughly translates into the intellectual capacity of children between 3-12 years of age. More than 75% of persons withIDhave the mild form and their intellectual capacity and potential may be underestimated in some cases ifIQis the only diagnostic criteria. However, the range in itself is an important factor to take into account when addressing nutrition and health issues. It is further important to recognize thatIDis also a feature of several rare disorders, and many disorders not yet identified, adding to the complexity of this group.