Diet vs. depression: The success of SMILES

As you may notice, this diet was not particularly stringent; it permitted grains, dairy foods, legumes, and even offered leniency with regard to small amounts of sugary beverages, alcohol, sweets and fast foods. It didn't even include much Omega 3-rich fish. The goal, apparently, was modest harm reduction in an effort to assure better adherence to realistic goals. Had patients followed a more committed Paleo-style diet, for instance, as have some of my patients who've successfully battled depression, perhaps the improvements would have been even more spectacular.

Additionally, the SMILES trial did not evaluate the efficacy of supplements and nutraceuticals vs. depression. Imagine the benefits that might have been attained with targeted supplementation!

How do you provide a "placebo" to control for the effects of all that attention provided to the research subjects? Control patients who did not receive the diet intervention were given social support counseling for an equivalent number of sessions.

SMILES did not aim to supplant conventional therapy with diet counseling. 55 of 67 patients were taking medication and/or undergoing psychotherapy. So this is not alternative medicine-it's integrative or complementary medicine, combining both conventional and natural interventions. As we?ll see, it turned out to be intelligent medicine.

At the beginning of the study and again at its conclusion after 12 weeks, each patient was given a battery of standard tests that are acknowledged by psychiatric professionals to gauge the depth of depression. The SMILES diet group achieved remission from depression at a rate of 32.3%. By contrast, only 8% of the SAD diet group achieved remission.

This adds up to an NNT (number needed to treat) of 4.1. That means that 4 depressed patients would have to undergo the diet intervention for one to achieve remission. While that may not sound impressive, bear in mind that many drugs have NNTs that are in the mid-to-high double digits. For example, statins have an NNT of 50-100 in terms of preventing heart attacks. A new depression drug with an NNT of 4.1 would be hailed as a breakthrough, would receive accelerated approval from the FDA, and reap billions for the pharmaceutical industry!

The authors conclude: "These results indicate that dietary improvement may provide an efficacious and accessible treatment strategy for the management of this highly prevalent mental disorder." They add, parenthetically, that the diet might yield additional benefits by relieving other physical ailments of depression sufferers.

Why should a healthier diet fight depression? There are multiple reasons:

• 1. It's anti-inflammatory. We recently did a podcast on the benefits of an anti-inflammatory diet with Dr. David Seaman, author of The DeFlame Diet. It's often overlooked that the brain is part of the body, and when you suffer from systemic inflammation, your brain metabolism might be impaired, resulting in altered mood. We see this clearly in rheumatoid arthritis, colitis, and lupus. Merely losing extra body fat attenuates inflammation. The dietary components that are most pro-inflammatory are sugar, refined carbohydrates, and vegetable oils. They permeate the junk foods that make up the SAD diet. By contrast, the Omega 3 oils, plant polyphenols, and herbs that are mainstays of the Mediterranean diet are anti-inflammatory.

• 2. It gets you off the blood sugar roller coaster. When you're "hangry," it's not the time to reach for a Snickers bar for a quick fix. Your blood sugar will soar transiently, only to plummet minutes later, perpetuating a vicious cycle of craving and binging. A high percentage of patients with depression are not just hypoglycemic, they're insulin-resistant. "Type 3 diabetes"-insulin resistance in the brain-has been identified as a cause of mood disturbance and cognitive impairment when the brain's energy production is compromised.

• 3. It's rich in vitamins and minerals. Plant foods provide magnesium, and animal protein is rich in iron, B vitamins, and the amino acids.

• 4. It's a source of Omega 3s. Nuts and fish provide Omega 3 fatty acids like linolenic acid, EPA, and DHA which are natural anti-depressants.

• 5. It offers sufficient protein. In several recent studies, it was found that a vegetarian diet was associated with higher risk for depression. Part of the problem may be the lack of readily utilizable protein due to a dearth of animal products. Amino acids are essential building blocks for feel-good neurotransmitters.

• 6. There may be microbiome effects. We are increasingly aware that a brain-gut connection exists. Studies suggest that probiotics may alleviate anxiety and depression. Adequate prebiotic dietary fiber is necessary to cultivate healthy intestinal flora. The SAD diet is almost bereft of soluble fiber, and is laden with artificial sweeteners, preservatives and emulsifiers which damage the microbiome.