Science Questions

Do our cravings reflect a lack of certain nutrients in the body?

I have read that the digestive system monitors food for the presence of certain nutrients and will encourage the brain to desire food until the need is met. Is this consensus science and if so which nutrients are involved? Andrew Reitemeyer, Facebook

Susie -   There is certainly some evidence if you induce a state of significant deficit that animals will show preferences for foods that contain those, but in terms of in a relatively healthy population, whether we actually show specific cravings for nutrients, that's a much tougher question to find evidence for.

Ben -   Marion, if I could bring you into this, thinking about the foods that people crave.  There must be some sort of developmental link in that that we crave things that we are familiar with and not necessarily nutrition that we need, but food that we like?

Marion -   Well certainly, the evidence from psychology suggest that food cravings are very common and they're very rarely, as Susie says, associated with a particular deficit.  Lots of research has shown that food cravings are common in men and women and they tend to be for foods that are very popular like chocolate and confectionery although men tend to crave things that are salty and savoury.  So yes, cravings are to do with familiarity and what you've learned to like under certain circumstances.  Certainly, in dieters, it seems that cravings can be stronger for foods that people are trying to avoid. 

As a psychologist, I'm very interested in food cravings because they quite often point to foods that are desirable because we’re meant to limit them, because they're tempting, and because we’re trying to restrict them when we’re dieting.  So, chocolate for example is a very commonly craved food and it’s not about any kind of nutrient deficiency, and this is really nicely demonstrated by a data from Paul Rozon who gave people who crave chocolate a box and he said, “Whatever is in the box, have this when you're craving chocolate.”  The box was either empty or it had capsules containing cocoa powder or white chocolate or milk chocolate.  White chocolate remember has no sort of cocoa.  It has just cocoa butter.  It doesn’t have any bioactive ingredients.  And what they found was that cravings could be reduced in chocolate cravers by white chocolate and by milk chocolate.  So it wasn’t that the cravings were really directed towards any kind of nutrient or any kind of physiological deficit, but rather because of the comfort of eating something that was really delicious – melt in the mouth, sugar and fat, absolutely delicious.  That's where cravings come from.

Answered by Susie Swithers, Purdue University and Marion Hetherington, University of Leeds February 2012