The Worst Diet for Depression

Feeling gloomy? Look to your diet. When you eat, you feed yourself—but you also feed your gut microbes. There are trillions of them in your gut and they make up a thriving community called the microbiota. Like you, they have their own favorite foods. Amazingly, they may be able to communicate their desires to you, giving you cravings. Yes, many of your cravings may be bacterially motivated!

This is not how to feel better.

Source: iStock/Zinkevych

Depending on what kind of microbes they are, those cravings can be good or bad for you. Some species of streptococcus in your small intestines just love sugar, and when you feed them, they can produce dopamine to make you feel happy. You think it’s just a sugar rush, but it also comes down to the lifestyle of your microbes.

These sugar-loving microbes are tweaking your brain, but they may also be inflaming your gut lining. They don’t always have your best interests in mind. The bacteria to celebrate are the fiber-feeders that live in your colon and manage to convert humble veggies into substances—metabolites—that act as a balm to your gut lining.

There’s a good reason the acronym for the Standard American Diet is SAD.

It turns out that you can divide food into two broad categories: healthy and inflammatory. You likely know which is which already. Those foods manufactured to be irresistibly delicious—I’m looking at you, Ronald, Dunkin, Wendy, Ben, Jerry, and the Cheetah dude—are not on the healthy list. Yes, you can have these as a treat on occasion, but in the modern world, we are encouraged to make every meal a fat-infused flavor fest.

Lemon juice on broccoli? Not so much.

There is a list of these low-nutrient gut bombs, called the Dietary Inflammatory Index (DII) that researchers use to seek out correlations. Recent studies show that these popular foods are linked with depression and other mental disorders. A new meta-analysis from China shows just how dangerous they can be. The researchers found an overall 25 percent increase in depression and an 85 percent increase in distress for those eating an inflammatory diet. Alarmingly, they found a four-fold increase in schizophrenia on such a diet.

Studies like this only show correlations, but the Chinese researchers also found a dose-response curve that looked suspiciously causal: For each one-unit increase in the DII, there was a 6 percent rise in symptoms of depression.

This is not the first study of inflammatory foods and health. Previous studies have noted an association between a junk-food diet and obesity, heart disease, type 2 diabetes, and cancers.

How do inflammatory diets affect health?

Inflammatory diets increase levels of cytokines, molecules that the immune system uses to indicate inflammation. Systemic inflammation is known to affect the brain, possibly by allowing toxins or bacteria to pass through the blood-brain barrier. That alerts the immune system, which may enter the brain to chase them down. However, the immune system is not fastidious and can cause a lot of collateral damage when it goes on the warpath.

But where are these bacteria and toxins coming from? By and large, they are escapees from the gut. In the gut, they may be ideal citizens, helping to protect us from the billions of pathogens that permeate the planet. However, no matter how beneficial microbes are in the gut, they are nothing but bad news in the bloodstream. The heart dutifully pumps these interlopers to every organ in the body and then the immune system chases them down with its typical heavy hand. Researchers speculate that sugar- and fat-loving bacteria may erode the gut lining and initiate this whole miserable process.

The China study nicely complements a recent, large study at King’s College London also showing that inflammation is a fellow traveler with depression.

The British researchers looked at 27,000 subjects with major depression and found they had elevated levels of inflammatory proteins. They weeded out factors including genes, age, sex, BMI, smoking, early-life trauma, and socioeconomic status. All that was left was a significant association between depression and inflammation.

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What foods are inflammatory?

So, what are these inflammatory foods? Here are the top five:

1. Sweets: candy, pie filling, ice cream
2. Refined carbs: buns, pasta, baked potatoes
3. Processed meat: hot dogs, sandwich meat, sausage
4. Alcohol: beer, wine, spirits
5. Hydrogenated trans fats: French fries, pie crust

In other words, a typical American cookout. Sigh.

These foods—along with most processed food, fast food, and junk food—all result in a rise in inflammatory markers. As delicious as they are, we would be wise to pace ourselves.

Eating greens to beat the blues

What are the anti-inflammatory foods? The top five:

1. High-fiber veggies: artichoke, asparagus, broccoli
2. Greens: spinach, kale
3. Fish: salmon, sardine, cod
4. Berries: strawberries, raspberries
5. Ferments: sauerkraut, kimchee, yogurt

I hear some of you weeping, but you can make terrific meals around these foods with a little culinary kick-up. Ginger, garlic, onions, peppers, and most spices also make the good list, so feel free to jazz things up. I’m not here to tell you to give up the BBQ. But adding some of the good foods to your diet can really improve your gut ecology.

It turns out that our guts were designed for an ancient natural environment where food was scarce and you could spend hours just tracking down a tuber. You needed to squeeze the most out of it. In times of scarcity, microbes that can produce fat from fiber are pretty terrific.

In times of plenty, however, that microbial efficiency can backfire. Thus the epidemic of obesity around the world. Today, we indulge ourselves and make every meal a treat. Our ancestors would be aghast! They ate to live; we live to eat.

Knowledge is power. Research like this gives us important insight into the mysteries of our own microbiota. Knowing that your microbes may be in charge of your cravings is a good place to start the introspection. Assert yourself, even though your microbes are weirdly powerful. When you eat your broccoli, your beneficial microbes will be grateful and their numbers will bloom. These good bacteria will beat back pathogens, some of which can lead to gut issues.

Once you start to shift your microbes to a friendlier ecosystem, you may feel better, gut-wise. And that may make you feel better all over. Amazingly, these simple diet changes can make you happier—priceless advice that won’t cost you a thing.

Why not give it a try? You have nothing to lose but gloom.