Quite by accident, I came across an article proposing fortification of rice to prevent nutrient deficiencies. I'm not against fortifying rice, since it could greatly improve the health of people for whom it's a staple. But the fact that rice needs to be fortified belies that idea that rice, or grains in general, are nutritious enough to be a dietary staple. It hasn't done much good for people who depend on it:a-Rosas. The Cochrane Library 2012, Issue 6.
[A] concern [with fortification] may relate to the possibility of over-consumption of rice given the potential beneﬁts of additional vitamins and minerals. As a public health intervention, the use of a vehicle would imply not encouraging the population to consume greater amounts of the ’fortiﬁed’ rice. Higher consumption of white rice is associated with a signiﬁcantly increased risk of type 2 diabetes, especially in Asian (Chinese and Japanese) populations.
Micronutrient deﬁciencies of public health signiﬁcance are all widespread in most high rice consuming countries.
Poor dietary diversity and dependence on cereal-based diets, which are common in developing countries, are major contributing factors to the high prevalence of micronutrient deﬁciencies. Cereals in addition to being poor sources of vitamins and minerals also contain high quantities of other dietary compounds that decrease the absorption of certain micronutrients, often called 'anti-nutrients’ (Graham 2001). For instance, iron and zinc absorption is signiﬁcantly inhibited by phytic acid, present in cereals and other grains; polyphenols, contained in red wine and chocolate; or calcium, abundant in dairy products. On this basis, dietary bioavailability of iron has been estimated to be in& the range of 14% to 18% for mixed diets and 5% to 12% for vegetarian diets. (Emphasis added.)
As for those healthy rice-eating Asians, "production is rising in the South but falling in the East" and "consumption has shifted to other foodstuffs in line with income growth."