We have just published a paper in which we review the literature on the nutritional adequacy of the Andean diet. We have been working on this for a couple of years and it is good to finally get it published.

We reviewed all the available research that documents the diet of people living in the Andes in Colombia, Ecuador, Peru and Bolivia, extracted the data and tried to figure out what it tells us about the adequacy of their diet. For me, there are two take home points:

1. Dietary data suck.

The tool most commonly used to evaluate the diet is the “24-hour dietary recall”. With this tool, the interviewer asks the respondent to remember and describe in detail, including quantities, the foods that they consumed the previous day. As you can imagine, this is hard to do accurately. We have some tricks and guidelines to help us to do it better, but the accuracy is low, with most individuals under-reporting what they ate.

We can tell there is under-reporting by comparing the caloric requirements of individuals to the calorie content of the food that they report eating. In the reviewed literature the reported intakes are about 10 to 50% less than estimated requirements. You can see in Figure 2 from the paper, copied below, that the average energy intakes reported in the reviewed literature (each grey line represents a different study) are almost always below the estimated energy requirements (red lines are for highly active people and green lines are for people with light activity levels). This isn’t possible – while energy intakes can be less than requirements for an individual for a period of time, it cannot be chronically less than requirements or… they will die. And while intakes may be less than requirements during the hungry season, or in famines and disasters, to have the intakes less than requirements in almost every report from the last 40 years in the Andes just isn’t possible.

It isn’t just in the Andes where this happens. We have helped on dietary surveys the last couple of years in Canada, Rwanda and Kenya – large scale, well-funded surveys that use 24 hour dietary recalls. And the results were similar, with impossibly low average intakes. You can see similar results in most published studies.

So why do we continue with the 24-hour recalls? Well, the don't totally suck. There are three reasons for using them: (1) despite their weaknesses, they do give a mountain of data that can be useful for some specific purposes (e.g. for use in food fortification programs, for estimating dietary diversity, for estimating relative changes); (2) there are other tools for dietary assessment, but they are either less accurate than the 24-hour recall, or much more expensive; (3) I don’t think many of the researchers realize that the problems with the tool are so severe. The alternative is to not assess nutrient intakes and we simply aren’t ready to give up such potentially useful data. We are using 24 hour recalls as a monitoring tool in our “Small Animals, Big Changes” project – the data collection team has been well trained, and, for a number of technical reasons, we are able to get reasonably good data. But for most purposes, for most situations, it is time to move on to other methods.

2. Fat intakes are dangerously low.

Children under five years of age should have 30% or more of their dietary energy from fat. In almost all the reviewed studies, children’s fat intakes were much less than 30%, with about one-third less than 10%. While there is under-reporting of total intake, we assume, somewhat hopefully, that the under-reporting is equivalent across the whole diet, so that the percent energy from fat is more-or-less accurate.

Dietary fat is required for numerous purposes. In addition to being a rich energy source, it is a nutrient in its own right, required in the building of the brain and nervous system, required for good heart health and weight maintenance, among other things. Chronically low fat intakes are likely having important, but under-recognized, health impacts.

We have to be careful about how we increase fat in the diet. Globally, the levels of dietary fat are increasing, but it is largely through unhealthy ultra-processed foods. We want to increase dietary fat in these populations, but not through increasing their intake of junk food. We have worked on increasing the consumption of high-fat legumes in Ecuador, and one of the primary motivations of our project “Small Animals, Big Changes” in Bolivia is to increase the fat in the diet through the consumption of more meat, eggs and milk.