Veg. Less depression

 According to NutritionFacts.org, Michael Greger discusses several possible reasons vegetarians may have a lower long-term risk of depression.

The key finding he highlights is a large prospective study from Taiwan that followed more than 3,500 vegetarians for about nine years. Vegetarians had about a 30% lower chance of developing depressive disorders compared with non-vegetarians.  

Greger notes that earlier research was mixed:

• Some studies suggested vegetarians had fewer depressive symptoms.
• Others found the opposite.
• Some longitudinal studies in Germany and the United Kingdom suggested people with existing psychological distress may be more likely to adopt vegetarian diets later.  

He proposes several mechanisms that could explain a protective effect from well-planned vegetarian diets:

1. Lower inflammation
   Chronic low-grade inflammation has been linked to depression. Plant-based diets tend to be richer in anti-inflammatory foods such as fruits, vegetables, legumes, and whole grains.  
2. Higher antioxidant intake
   Plant foods contain antioxidants that may help reduce oxidative stress, which is also associated with mood disorders.  
3. Better gut microbiome health
   Fiber-rich diets support beneficial gut bacteria, and growing evidence links gut health to mental health through the gut-brain axis.
4. Better sleep quality
   Greger mentions that vegetarians may sleep better on average, and improved sleep could contribute to improved mood.  
5. Overall healthier lifestyle patterns
   Vegetarians often have lower rates of smoking, obesity, and some chronic diseases, all of which can influence mental well-being.

At the same time, the broader scientific literature is still inconsistent. Some meta-analyses have reported slightly higher depression scores among vegetarians, while others found no meaningful association after controlling for lifestyle and socioeconomic factors.  

So the current evidence suggests:

• A healthy plant-based diet may help reduce depression risk for some people.
• But causation has not been definitively proven.
• Diet quality likely matters a lot — whole plant foods appear very different from highly processed vegetarian diets.