1. Fish Oil (Flax Seeds Work Too)
Fish oil refers to two types of omega-3 fatty acids: EPA and DHA. These omega-3 animal fats are present in plankton, fish, and animal products.
The ratio of omega-3 to omega-6 is important. Since the average diet is overweight in omega-6, fish oil can help balance the ratio by providing omega-3.
The health benefits of fish oil include improved cardiovascular health and prevention of brain aging (controversial). Fish oil may also be an effective adjunct therapy in patients with major depressive disorder or other psychiatric illnesses.
One study conducted in healthy adults found that omega-3 supplementation may increase neural network efficiency by modifying brain activation [ref].
2. Vitamin D
Since humans have shifted to spending very little time outdoors, vitamin D deficiency has become increasingly common. Developmental vitamin D deficiency can cause abnormal brain development and has been linked to schizophrenia and an increased risk of dementia and Alzheimer’s disease.
Interestingly, one study speculated that the incidence of schizophrenia may lower along the equator due to increased exposure to sunlight (which would increase vitamin D synthesis in skin).
Vitamin D functions as a potent neurosteroid in the brain and can regulate circulating catecholamines (dopamine, norepinephrine). Preclinical data also suggests that vitamin D affects neuronal differentiation, axonal integrity, and brain structure and function [ref].
Probiotics are live bacteria that are beneficial to general health. When you lose beneficial bacteria (e.g., from antibiotic treatment) probiotic supplementation can help replace them. Probiotics also treat some common conditions of the GI tract, including: irritable bowel syndrome (IBS), inflammatory Bowel Disease (IBD), infectious diarrhea, and antibiotic-related diarrhea.
The composition of the gut microbiome is also linked to mental health. Studies in animal models suggest that a disrupted gut microflora induces behavior that mimics human anxiety, depression and even autism. Moreover, in some studies normal behavior was restored in animals by treatment with benign strains of bacteria.
Recently, the gut-brain axis has gained attention in the neuroscientific community.
One hot topic in the field has been the “gut-brain axis” or how bacteria in the gut can affect cognitive function, behavior and mood. For example, structural bacterial components (e.g., lipopolysaccharides aka LPS) elicit an innate immune response, and excessive stimulation may result in neuroinflammation (an inflammatory response in the brain).
Bacterial proteins can also cross-react with human antigens resulting in maladaptive immune responses. Moreover, bacterial enzymes produce neurotoxic metabolites such as D-lactic acid, ammonia, or propionic acid. Gut microbes can also hijack communication between neurons by producing hormones and neurotransmitters identical to those found in humans.
L-theanine is a nondietary amino acid and one of the few psychoactive agents that promotes relaxation and decreases anxiety without sedation. Along these lines, L-theanine may also reduce the perception of stress and modestly improve attention. L-theanine works synergistically with caffeine and other CNS stimulants because it can help reduce stimulant-related anxiety or edginess.
To date, hundreds of peer-reviewed papers have been published characterizing the neuroprotective and the prophylactic effects of curcumin against brain aging. The abundance of dietary curcumin (as tumeric) in curries may be one factors that accounts for the lower incidence of neurodegenerative disease in India.
Unfortunately, curcumin has low oral bioavailbility, and so some scientists have called into question whether curcumin supplementation will have any effect at all.
Curcumin bioavailability has been improved by formulations that include bioperine (pepper), which inhibits the CYP3A4 hepatic enzymes involved in the metabolism of curcumin, thereby increasing the concentration of curcumin in serum. Liposomal formulations of curcumin may also enhance blood brain barrier penetration and improve poor bioavailability.
Interestingly, ingesting curcumin by eating Indian curries containing tumeric may actually improve bioavailability (compared to direct supplementation) due to the oil (which is hydrophobic) used when cooking food.