We’ve known for a long time that diet affects depression, but the science has gotten stronger and stronger over time. Science has moved from diet affects depression, but we’re not sure how, to specific diets benefit those with depression, but we’re not sure exactly why, to more specific insights like a high-sodium diet causing depression. At this point, it seems to me that if you’re not looking at your diet as a possible treatment augmentation for depression, you’re missing out. Here are some recent insights about diet research and depression.

(There’s a TL;DR for this article, if you want to skip to the meat of the matter.)

Can Your Diet Really Treat Depression?

Research has been indicating for years that an unhealthy diet can increase depression risk, and even depression symptoms. However, the recommendations stopped at simply trying to eliminate processed foods, eat more veggies, and all the other common healthy-diet advice. We thought that a lower-quality diet could hurt you, but we didn’t know what diet might actually help you. This left people to figure out what “healthy” was on their own.

The Mediterranean Diet and Depression Treatment

Then, research came out about the MIND diet (read about it here), which is similar to a Mediterranean diet. The MIND diet does seem to improve people’s mental health, and new research shows it’s not the only one. Various dietary interventions have now been tried and show that they can treat depression.

For example, here’s a study that was done with 72 young men with moderate to severe depression. It showed that after 12 weeks on the Mediterranean diet, they were less depressed and had a higher quality of life.

Salt and Mental Health: What the Research Says

There are very few times science is willing to walk out onto the limb of causation. In other words, it’s very hard to say that one thing causes another. It’s much easier to say that one is correlated to or influences the other. This is one of the reasons that I almost never say that anything causes depression or bipolar disorder. Causation is incredibly difficult to prove.

However, two recent studies suggest that a high salt diet does cause depression and maybe anxiety. Here, an enormous study of half a million in the UK, followed for 12 years, found that people who usually added salt to their food had a 16% higher risk of depression and 5% higher risk of anxiety, and people who always added salt had a 37% higher risk of depression and 27% higher risk of anxiety. Those are numbers worth paying attention to.

But that doesn’t prove causation, like I said. This animal study is suggestive of it, though. While it is in mice, its results suggest that increased dietary salt intake does cause depression. (Note that while we all would like human studies to prove this, it’s likely impossible to design a study that would be ethical and show causation.) There are other ideas around salt and depression, too, however.

(Thanks to Chris Aiken, MD, for sharing this and lots of other incredibly useful research.)

Could Keto Help with Bipolar Disorder?

Lately, there has been quite a focus among some people on the ketogenic diet (also known as metabolic therapy) for the treatment of bipolar disorder and schizophrenia. The research is still in its infancy here, but it appears that some people with serious mental illness may improve on the keto diet. A small study showed improvements in overall health markers and improved psychiatric outcomes over four months.

This study of 31 people with refractory major depressive disorder, bipolar disorder, or schizoaffective disorder also showed impressive improvements in metabolic health along with depression scores and other psychiatric markers.

(Here’s some information about why keto may help those with bipolar disorder. They’ve been looking at the connection for years.)

This is all very preliminary. As this review states:

Although there is no high-quality evidence of LC/KD [low-carbohydrate/ketogenic diets] efficacy in mood or anxiety disorders, several uncontrolled studies suggest possible beneficial effects. Robust studies are now needed to demonstrate efficacy, to identify clinical groups who may benefit and whether a ketogenic diet (beyond low carbohydrate) is required and to characterise adverse effects and the risk of relapse after diet discontinuation.

Keep in mind, keto studies have a decent-sized drop-out rate (those who couldn’t stick to the diet), and that’s in populations like inpatients, so when this diet is done medically, it is extremely hard to maintain. Also, realize that if you want to try this diet, you need to do it with medical supervision. Bad things can happen to your body if you try a ketogenic diet without knowing what you’re doing.

Why Diet Affects Mental Health: The Science So Far

We don’t know exactly why diet affects depression. Sure, you could just say that “you are what you eat,” but that’s not much of an answer. Some nutrients, like vitamin D, clearly impact mood, so it’s clear that if you’re not getting enough of it, you may be more depressed or anxious. But other things aren’t so clear. Some say the anti-inflammatory properties of certain diets may be why they work, while others say it’s simply weight loss that does the trick (posited here). Another study mentions diets may work to improve depression through changes to the gut microbiome, reduction in oxidative stress, and modulation of hypothalamic-pituitary-adrenal axis function. So, people have their theories, and over time, we’ll learn more.

Diet Isn’t a Cure — But It Could Be a Powerful Part of Your Depression Treatment

What’s clear is that the link between diet and depression is no longer soft science or speculative — it’s becoming increasingly precise and compelling. From general dietary quality to specific components like sodium, and even to targeted dietary strategies like the Mediterranean or ketogenic diets, what we eat can shape our brain chemistry, inflammation levels, gut health, and ultimately, our mood.

Of course, diet isn’t a magic bullet. It won’t replace therapy, medication, or other evidence-based treatments for depression. But, as a growing body of research suggests, it can be a powerful adjunct — something that works alongside your existing treatment to make it more effective. If you live with depression and haven’t considered your diet as part of your care plan, now might be the time to start. Even small changes could help shift your mental health in a more hopeful direction.

FAQ: Diet and Depression

Can diet really improve depression symptoms?

Yes, emerging research shows that dietary changes can meaningfully improve symptoms of depression. Diets like the Mediterranean or MIND diet have been linked to reduced depression severity, likely due to their anti-inflammatory properties, impact on gut health, and nutritional density.

What is the MIND diet, and how does it affect mental health?

The MIND diet is a hybrid of the Mediterranean and DASH diets, designed to support brain health. It emphasizes leafy greens, berries, nuts, whole grains, and fish. Studies have shown that following the MIND diet can reduce the risk of depression and cognitive decline.

Does salt increase the risk of depression?

Recent studies suggest that a high-sodium diet may increase the risk of depression and anxiety. In a large UK study, people who frequently added salt to their food had significantly higher rates of depression — up to 37% higher for those who always added salt.

Is the keto diet effective for bipolar disorder?

While research is still early, some small studies suggest that a ketogenic (keto) diet may improve symptoms in people with bipolar disorder, especially those who haven’t responded to other treatments. However, it’s a strict and medically demanding diet, so it should only be attempted with professional supervision.

Why does diet affect depression?

There’s no single answer, but several mechanisms are being explored: nutrient deficiencies, inflammation, oxidative stress, hormonal regulation, and gut microbiome imbalances all appear to play a role. Diet influences these systems, which may explain its impact on mood.