The War on Legumes

Chickpeas were among the legumes the Food and Drug Administration (FDA) listed as an ingredient in dog food that might be linked to reported cases of canine dilated cardiomyopathy.

In July, the Food and Drug Administration (FDA) released a letter about legumes in dog food, and, ever since, pet specialty retailers have been coping with alarming and confusing information about what is now a very large segment of their assortments. 

For those of you who are not bean fans, legumes include lentils, peas, beans and chickpeas. These ingredients are prominent in many popular premium grain-free dog and cat foods, which represent the second wave of grain-free pet foods. Many consider foods with legumes to be an improvement on the first wave of grain-free dog foods, in which the main carbohydrate was white potatoes. Kibble, after all, cannot be made without starch. White potatoes, however, are a fast-release carbohydrate, and a diet heavy with spuds might lead to instability of blood sugar levels and other issues. 

I sometimes have to remind people new to the industry the background on how "grain free" became a watchword for quality. In the 2000s, multiple pet professionals concluded that many dogs were suffering from allergies to corn, wheat or soy. The result was a wave of foods with ingredients such as brown rice and oats. Clever marketers seeking product differentiation in the marketplace created the term "grain free," after which the widespread concern about corn and wheat extended to all grains, including brown rice and oats. When grain free became popular, these proven ingredients were tarnished, even though millions of pet owners were seeing excellent results with these two ingredients. Marketing themes incorporated the notion that dogs’ diets should imitate those of wolves, despite the fact that thousands of years of evolution have made the two species’ nutritional needs and habits very different. Major pet food brands with big ad budgets have increased the public’s association of grain free with high quality, and, as a result, a large proportion of dogs are eating grain-free diets beginning in puppyhood—before they have a chance to develop food allergies.

What the FDA aimed to do with its letter in July was "alert" pet owners and veterinarians that they received reports of a canine heart condition called canine dilated cardiomyopathy (DCM) in dogs eating pet foods containing legumes or potatoes as prominent ingredients. The veterinarians who reported these cases were accustomed to seeing DCM in certain large- and medium-breed dogs, but were alarmed when they began to see them in golden retrievers, Labradors and a handful of small-breed dogs. In four cases, the dogs had low taurine levels, and in four they did not. 

Reviewing the articles available to me, I understand the number of cases of DCM reported in breeds not normally predisposed to the condition was in between 70 and 80, and that 54 percent were on grain-free diets. With the total population of these breeds probably well over a million, it is a toss-up whether this proportion is enough to warrant investigation. Also, the relationship with low taurine levels, which is associated with DCM in the breeds prone to that condition, was seen in only four of these dogs, and all were large breeds. 

So we are faced with two questions. First: Do grain-free dog foods that feature legumes or potatoes prominently cause DCM? Second: Do they cause low taurine levels? So far, all we know about is a correlation between diet and DCM, which does not mean causation. Also, with only four cases of low taurine levels reported, there is not even a correlation between diet and taurine levels. In fact, the low number of cases could lead you to conclude that there is not even a correlation, which points to the strong possibility that diet is not a cause at all. 

Correlation Is Not Causation

The pet nutritionists I know—ones with Ph.D.s in the field and who have participated in research for years—generally feel that veterinarians often blame diet for conditions they can’t diagnose. Dog owners do the same. Reading consumer postings on various dog information websites, I was struck by how many people wrote, "My dog developed a condition because of his diet" as a default explanation. Given that so many dogs are being fed grain-free diets now, odds are that many of those of breeds whose DCM was a surprise were eating those diets. As genetics is thought to be the origin of DCM in breeds that typify that condition, it is probably at the root of these new cases, too.

Another volley in the war on legumes came from an article in an industry journal that strongly suggested that their inclusion at high levels in pet food could lead to gas and loose stools. Much of the article consisted of speculation and hypothetical math leading the reader to be very concerned about legumes. Buried in the text was that the only evidence available shows that legume-rich dog foods are associated with no immediate problems at all.

Of course, anyone dealing with customers must take their concerns very seriously, help them separate fact from conjecture and offer alternatives such as high-quality foods with brown rice. The entire episode, although causing worry among customers, has an upside, which is to remind the public that food allergies are less common than many suppose and that some formulas, although unfashionable, are very good. 

Barry Berman is president and co-founder of Nex-Pet, a co-op for independent retailers, and Grandma Mae’s Country Naturals pet food company. He is also vice chairman of World Pet Association (WPA). Contact him at