What follows is a true story. It really happened, and you can draw your own conclusions.

Just over 13 years ago, on a snowy evening in January 2003, my daughter and I went out and brought home the sweetest, gentlest, 8-week-old Labrador Retriever puppy. She was a chocolate lab, and so we named her Mousse. Mousse played ball; Mousse cuddled with the children; Mousse helped me weed the garden; Mousse stole food from the kitchen table when she thought no one was looking; Mousse hung out with the chickens and enjoyed visiting with our friends and neighbors, both human and canine. Mousse became family, and all was well.

When Mousse turned 10 a few years ago, I noticed that her coat wasn’t quite as shiny, plus she was starting to get some dandruff. We began adding some canola oil to the duck-and-potato kibble that Mousse been eating since she was two. Why canola? We decided on canola oil mainly for economic reasons. It seemed kinda silly to buy high-quality oil for a dog, even Mousse. I wasn’t exactly sure how I felt about canola, but it seemed a reasonable compromise. [And why duck-and-potato kibble? It turned out to be the most reliable way to get rid of the chronic ear infections from which she suffered when she was little.]

After a few weeks with the canola oil, the dandruff began to disappear and Mousse’s coat got shiny again — so that was good. She was getting older, though, and definitely a little stiffer, especially in the mornings. Here’s where I give a shoutout to our beloved friend and vet, Ben, who okayed a daily dose of glucosamine. It seemed to help, so we kept it up.

Then there was a big sale at the supermarket and, on a whim, we decided to try corn oil instead of canola. Just like with the canola oil, we poured a couple tablespoons of corn oil on Mousse’s kibble every day. Within days, she was so stiff she could barely propel herself up and out in the mornings. Climbing stairs became out of the question. We were horrified. The situation called for drastic action.

We immediately switched to olive oil, hoping it would help her joints heal, and that is exactly what happened. Within a couple weeks, her joints were flexible again. She was rising easily in the mornings, and she didn’t seem to be pain anymore. We were thrilled! It was like magic. Although she didn’t heal completely — she no longer climbed the stairs to the second floor, for example — she was, for the most part, back to normal.

At this point, we switched back to canola oil, promising never to use corn oil again. But what happened next shocked us: Within just a few days, Mousse’s joints began to stiffen up again. Though it was not as dramatic as it had been following the addition of corn oil to her diet, it was clear to us that things were getting worse again. We went back to the olive oil, and once again she healed. We gave the canola another try, and once more she became stiff. We returned to the olive oil, once and for all.

Here is what you need to know about products like corn oil. Corn oil is high in omega-6 fatty acids, which are strongly pro-inflammatory. Just as we need omega-3’s to reduce inflammation in our bodies, we need omega-6’s to cause inflammation, to help our immune system fight foreign invaders. It’s a balance, which we get exactly right when we eat corn on the cob, whole-grain corn meal, and the like. It’s the same with soybean oil. Edamame, tofu and miso provide exactly the right balance of omega-6’s and omega-3’s, but commodity-based seed oil products, like corn oil, soybean oil, “vegetable” oil and cottonseed oil, are sky-high in the omega-6’s that increase inflammation.

Until this experience with our beloved chocolate Mousse, I reserved judgment on “canola” oil, an acronym of sorts derived from CANadian OiL Association. But not anymore. Whatever canola oil is, it no longer has a place in my kitchen. And I no longer wonder if corn oil is having a negative effect on the health of my friends and patients — the answer is clear to me.