UPDATED May 27, 2016 // ATLANTA ― Scientists have developed a new evidence-based scale that rates animal- and plant-based foods that improve depressive symptoms.
Research on this scale and on foods that help nourish the brain was presented here at a standing-room-only session during the American Psychiatric Association (APA) 2016 Annual Meeting.
There is increasing evidence regarding the crucial role that diet plays in brain health, particularly in the areas of depression and dementia, said Drew Ramsey, MD, assistant clinical professor of psychiatry, Columbia University, New York City, who was one of the session speakers.
"The data are very clear that there's a powerful prevention signal when we help our patients eat better," Dr Ramsey told Medscape Medical News.
Plant foods are high on Dr Ramsey's brain food scale. To develop this nutrient profiling system, he and his colleagues assessed the literature and compiled a list of what they call brain essential nutrients (BEN) that affect the treatment and prevention of depression.
Key nutrients include long-chain omega 3 fatty acids, magnesium, calcium, fiber, and vitamins B1, B9, B12, D, and E.
They then gathered nutritional data for top food sources of BEN from the Agricultural Research Service Nutrient Data Laboratory and used a formula to calculate the Brain Food Scale score.
"We were very interested in using the scientific literature to winnow down the key nutrients that have evidence that they are very, very involved in depression," said Dr Ramsey.
In addition to plant sources of these nutrients, they wanted to include animal sources, because some nutrients, such as vitamin B12, are predominantly found in meat and other animal products and are "absolutely critical for brain health," said Dr Ramsey.
Possible mechanisms by which these foods may boost brain function include neuronal membrane stabilization and anti-inflammatory effects.
The investigators plan to submit this research for publication, said Dr Ramsey.
Although these nutrients are key to brain function, 2009 statistics from the US Department of Agriculture show that most Americans are not getting enough of them. For example, the percentages of the US population that do not meet the recommended daily allowances for these key nutrients are as follows:
Vitamin E: 86%
Vitamin B6: 35%
Vitamin B12: 30%
In addition to leafy green vegetables, researchers highlighted the importance of organ meats, game meats, nuts (pecans, walnuts, and peanuts), bivalves (mussels, clams, oysters), mollusks (octopus, squid, snail), and fish (salmon and sardines). Although it is recommended that patients eat 8 to 12 ounces of fish a week, it is important to choose fish that are lower in mercury. Individuals should therefore limit consumption of shark and swordfish.
Dr Reynolds also stressed that he wants to help patients make better choices when it comes to meat. Those choices, he said, should include grass-fed and pastured animals.
Although the research focuses more in the areas of depression and dementia, new trials are looking at attention-deficit/hyperactivity disorder, anxiety, and addictions, said Dr Reynolds.
Although most of the emerging data are from case reports and epidemiologic studies, the first randomized controlled study, known as the SMILES Trial, is testing the impact of a diet rich in many of these nutrients on major depression.
The study includes 176 patients with major depressive episodes at two centers in Victoria, Australia. Participants were randomly assigned to either a dietary intervention group, which focuses on advocating a healthy diet, or a social support group.
Although results of this trial likely will not be published until later this year, Dr Ramsey's group has had a chance to discuss the results with its investigators, and the results are "positive" and "better than expected."
"What's exciting about that is that it helps give the psychiatric community and our patients another set of tools in terms of treating and preventing mental illness," said Dr Ramsey.
Growing Interest in Food as Therapy
This is the fourth consecutive year that the symposium on food and the brain has been held at the APA's annual meeting, and every year it has drawn increasingly larger audiences. This year's session drew over 400 psychiatrists and other experts, said Dr Ramsey.
In addition to Dr Ramsey, Emily Deans, MD, instructor of psychiatry, Harvard University, and Laura LaChance, MD, fifth-year psychiatry resident, University of Toronto, also spoke at the session.
"It's clear that changing our eating habits is no simple matter. The good news is that psychiatrists are uniquely suited to help our patients make changes to complex behaviors ― this is bread and butter in psychiatric care. Until recently, however, it's been unclear what kind of diet patients with mental disorders should strive to consume," said Dr LaChance.
Dr Ramsey stressed the importance of talking about food and nutrition with patients struggling with mental health.
Psychiatrists, said Dr Ramsey, should regularly ask patients what they are eating and whether they have any food aversions or allergies. Using a volunteer from the audience, he demonstrated a therapist/patient interaction that incorporates diet. This volunteer said she follows an "intermittent fasting" diet to help control bipolar disorder.
This type of fasting increases production of ketones, which, according to some evidence, are a "cleaner" fuel source for the brain, Dr Ramsey said in a follow-up interview. Some case reports suggest that such a diet is beneficial for patients with bipolar II disorder, which is associated with less intense elevations of mood compared with bipolar I, he said.
A number of such "specialty diets," which also include the gluten-free diet and the paleo, or caveman, diet, as well as vegetarian and vegan diets, are becoming hugely popular. Dr Ramsey talked about the "engagement" surrounding "food, food justice, food sourcing" and the popularity of farmers' markets.
He stressed that "it's our job as physicians to understand these diets and their risks and benefits."
Vegan, Vegetarian Diets
One of the risks, at least with the vegan diet, and to some extent the vegetarian diet, is the lack of vitamin B12. A deficiency in this vitamin can lead to depression, anemia, and eventually to "irreversible damage to neurons," said Dr Ramsey.
A recent study that examined vegan populations showed that 52% of individuals were "frankly deficient" in vitamin B12 and that 23% had "insufficient" levels, he said.
A case report of 30 vegan mothers found that 60% of their offspring had developmental delays and that 37% had cerebral atrophy, Dr Dean told meeting delegates. There is a strong correlation between eating no meat and higher rates of depression and anxiety and worse quality of life, she said.
Although in some ways the vegan diet "makes sense," in that the North American diet is heavily laden with animal products, "that doesn't mean that the solution is to eat no seafood," said Dr Ramsey.
But during a lively question period following the session, which lasted for more than an hour, a psychiatrist who has been a vegan for several years took issue with some of the group's conclusions. She noted that a vegan diet has benefited her own health, including reducing cholesterol levels.
Although diet is a personal issue, and many patients follow what they believe to be a healthy diet, overall dietary habits have changed over the past century, and, generally, not for the better.
There has been a large shift from whole foods to processed foods. In addition, higher sugar consumption, more refined carbohydrates, and more foods with dyes, preservatives, and trans fats are being consumed.
Feed the Microbiome
Dr Ramsey was a vegetarian for more than a decade, but said he "wasn't feeling my best." He reported that his overall physical and mental health improved when he started eating seafood and sustainable sources of grass-fed meat as well as more dairy.
He lives part time on his family farm in Indiana, where he grows over 50 varieties of kale. His book 50 Shades of Kale, he said, has helped this leafy green vegetable get "a good foothold in the lexicon of American food."
Not only is kale a healthy food, but it's also fairly inexpensive. Other healthy foods that most families can fit into their budget include lentils and small red beans.
He and the other speakers discussed the extensive scientific literature related to these and other foods that boost brain function. Mounting evidence suggests that patients should be choosing more plant-based foods.
A plant-based diet "feeds the microbiome," said Dr Ramsey, adding that it contributes to the bacteria in the gut that appears to "play a tremendous role in our overall health."
Plants are also very "nutrient dense," so they have more nutrients per calorie.
Mustard greens, spinach, bell peppers, and other plant foods contain "phytonutrients." Research shows that these "signaling molecules," which include lycopene and carotenoids, help protect the brain, said Dr Ramsey.
American Psychiatric Association (APA) 2016 Annual Meeting: Presented May 17, 2016.