A year ago I co-authored a chapter in Diversifying Food and Diets with Andy Jones. This past week I was very pleased to learn that the entire book is now available free for download.

Our chapter is entitled “Biodiversity’s contribution to dietary diversity: magnitude, meaning and measurement”. For me, the most important point we had to make is represented in this graph, Figure 9.4, from the paper:

Each dot represents a food consumed by a woman in a survey we did in rural Bolivia a few years ago. The quantity of the food consumed is on the horizontal axis, and the vitamin A content of the food is on the vertical axis. The curved line represents the function of grams of food and vitamin A levels that would provide an intake of 500 μg of vitamin A, the recommended safe intake for adult women – you can eat a bit of a very rich vitamin A food like liver, or a huge amount of a food with a small amount of vitamin A, such as tomatoes. As you see, vitamin A is found in large amounts in very few foods – this is typical of vitamin A in any food system, and most foods do not have any vitamin A at all. So to eat enough vitamin A, there are two typical Strategies** that are promoted: (1) eat more of the vitamin A-rich foods (the classic nutrition intervention) and (2) find vitamin A-rich varieties of the foods that are already consumed in large amounts, which is the “new way” to do it, called “biofortification”, which uses biotechnology and breeding to develop varieties of foods with vitamin A (or iron or zinc or presumably any micronutrient of interest).

Our bottom line is that in most cases Strategy 1 is preferred for the following reasons:

First, with minimal training anybody can identify a food rich in a desired nutrient, e.g., most red/orange foods have vitamin A, meats have iron, zinc, and B-12, green vegetables have folate). In contrast, there is no easy way to determine if a biofortified food has high levels of a nutrient. It requires continued involvement of experts with expensive equipment to measure the nutrient levels. (There is an exception with sweet potatoes, where the deeper the orange of the flesh, the higher the vitamin A levels, but a zinc-rich bean would look the same as low zinc bean).

Second (not included in the chapter, but also important), farmers choose which varieties of crops they grow based on numerous criteria – production characteristics, drought tolerance, maturation rate, taste, etc. Many small farmers grow multiple varieties to get harvests with different characteristics (e.g., an early harvest bean, a bean for eating fresh, and a bean for storing). For Strategy 2 to be effective there would need to be biofortified versions of each of those multiple varieties. Multiple biofortified varieties are not available for most crops – rather a single biofortified variety is promoted and it would require displacing most of the existing varieties in order to be successful as a nutrient source. It doesn’t make sense to me to use such a strategy when other strategies (e.g.,Strategy 1) are available.

In previous work in Ecuador with mineral-rich quinoa and fat-rich lupine beans, and in our current work in Bolivia (promoting the production and consumption of sheep and chickens to increase fat and micronutrients in the diet), we are using the first strategy. Similar strategies will probably be tried in our new research project in Vietnam and Thailand (more details in an upcoming blog post).

**There are other strategies for increasing micronutrient intake – consuming micronutrient supplements, and micronutrient fortification of foods (e.g., iodized salt), but these do not fall in the domain of “biodiversity” and were not addressed in the chapter.