Trying a new diet to start the new year? Researchers say one option may help with more than just your waistline.
The Mediterranean diet focuses on vegetables, fruits, nuts, and fish. In a recent study, researchers found people strictly following the diet reported a 33% lower risk of being diagnosed with depression, compared to those least likely to adhere to it's guidelines.
Researchers say they wanted to look into the role nutrition plays in depression, noting in the study that depression affects more than 300 million people world wide, including 7% of all women and 4% of men. The World Health Organization estimates depression and anxiety disorders cost the global economy $1 trillion in lost productivity each year. But, researchers say conventional treatment is only effective in one of every three cases.
Dr. Camille Lassale carried out the research alongside her colleagues at University College London. She says "we know that depression is often accompanied by change in appetite and eating behaviors", but they wanted to take a look at whether that association could also go the other direction. So, they began a systemic review of previous diet studies, taking 41 projects into account. Four of those specifically looked at the link between a traditional Mediterranean diet and depression over time in more than 36,000 adults.
Researchers say through that analysis they found several factors causing damage to the brain can actually be controlled by a person's diet. "Diet can influence mental health by causing damage to the brain", says Dr. Lassale. "This can be due to oxidative stress (a harmful chemical process), insulin resistance, changes in blood flow and inflammation. A diet rich in anti-inflammatory and anti-oxidant components, commonly found in fruit, vegetables, nuts and wine (which should be drunk in moderation), can directly affect the brain by protecting it from oxidative stress and inflammation. Inflammation can also affect the neurotransmitters (the brain's messenger molecules) responsible for regulating emotion."
Subjects with the highest dietary scores shared common elements: higher fruits, vegetables, and nut intake, and lower amounts of pro-inflammatory foods like processed meats, trans fats, and alcohol.
Researchers concluded that there's enough observational evidence to suggest sticking to a healthy diet, the traditional Mediterranean diet in particular, and avoiding inflammation is associated with a reduced risk of depression. But, they say this is preliminary evidence, and suggest more well-powered clinical trials are needed to see if diet can prevent depression before it starts, lessen it's severity, and stop it from reoccurring over time.
They also found the results interesting regarding the connection between a person's stomach and their brain. Dr. Lassale says it all centers around the microbes in your gut, known as gut microbiota. "These microbes can break down the nutrients we eat and create molecules that may be inflammatory or that stimulate neural activity. They communicate with the gut and brain neurons and can therefore influence behavior. Diet is a key modulator of gut microbiota. In animal studies, eating plant-based foods improves the microbial composition in the gut, whereas high-fat diets appear to disrupt the microbial balance." Dr. Lassale adds, "when there is an imbalance in the microbes in your gut, it can cause the intestines to become permeable, letting big molecules pass into the bloodstream, and these molecules can interact with brain function."
That interaction may be part of the reason the Mediterranean diet is so effective, and other diets could prove to be problematic. For example, when it comes to the Keto diet, Dr. Lassale says some studies have suggested it may help with psychosis, but more studies are needed. The bigger issues is that high fat diets and low fiber diets tend to be problematic for gut health. Because of that, Dr. Lassale says "the keto diet needs more good quality evidence before it should be recommended. It may do more harm than good." She says she's most interested in seeing whether it has a noxious effect on gut health.
Researchers say they hope this analysis is just the start of more studies to dig into the link between what we eat and how our brain functions, noting that if there's a way to influence mental health with nutrition it will represent an important step to helping the millions who suffer from depression every day.
Kim Lucey is a freelance journalist with more than a decade of experience in the field. Her career has included coverage of big breaking news events like the Sandy Hook school shooting, lockdown in Watertown, MA following the Boston marathon bombings, and Superstorm Sandy. Her in-depth reports have garnered awards, including a focus on treating mental health issues in children. Currently, she is a reporter at a television station covering the news across the Greater Boston Area with an appreciation for fact-finding and storytelling. Follow Kim on Facebook and Twitter.