In the hierarchy of organs, the brain is arguably the most important organ in the human body. It is the central command post for how we think, feel, and consequently act on the multitude of stimuli that we must respond to. Despite this importance, the cells that make up the brain — neurons — are largely unable to regenerate themselves. Neuronal cell death can occur in many ways: physical damage (e.g., concussions), oxygen deprivation (e.g., during a stroke), and neurodegenerative diseases (e.g., Alzheimer’s disease). Because these are such special cells, how does the brain maintain itself?

One of the ways it does this is through a protein called brain-derived neurotrophic factor (BDNF). It is a key protein that plays an essential role in the survival and growth of neurons. BDNF elicits brain cell maintenance by partnering with its receptor protein called Tropomyosin receptor kinase B (TrkB). When these two proteins interact, they help promote signaling between neurons (that is, how brain cells communicate with each other) and neuroplasticity (the capacity for the brain to grow and learn new things). Therefore, having BDNF present is critical to maintaining proper brain function and health.

BDNF and Depression: A Key Connection

Lacking BDNF can negatively affect an individual’s ability to learn, recover from traumatic brain injuries, and maintain mental health. Loss of appropriate BDNF levels has been implicated in cases of depression. For example, in a small 35-patient cohort study, it was discovered that the BDNF protein was lower in patients diagnosed with major depressive disorder. This connection between BDNF and depression has been further examined, contributing to the generation of the “neurotrophic hypothesis of depression.” This working hypothesis posits that depression is rooted in a lack of proper neuronal growth and support in the brain, with BDNF being one factor that could affect this balance.

Even though it is not fully understood how BDNF can impact mental health, it still holds great promise as a potential way forward for depression treatments. One approach to address this is to utilize the link between the gut microbiome and mental health (popularly known as the gut-brain axis). Several research groups have pursued this line of inquiry. One recent analysis of present medical literature supports the idea that probiotic cocktails can increase BDNF in patients suffering from mental health disorders. They pointed out that a combination of two bacterial genera, Lactobacillus and Bifidobacterium, are strong contenders for the basis of future larger-scale studies to advance this prospective treatment.

How to Increase BDNF Naturally

In addition to microbiome approaches, there is other evidence that suggests exercise and dietary changes as alternative methods of increasing BDNF. This has been observed in both laboratory and in-patient studies. For example, in rats that have exercised, it was observed that messenger RNA (the molecule that encodes the instructions for protein production) levels for BDNF were significantly increased compared to sedentary rats. Similarly, several studies have shown that BDNF increases in adult patients with multiple sclerosis who performed therapeutic physical activity.

Dietary changes also appear to influence BDNF levels:

• Polyphenol-rich foods: Fruits such as apples, mangos, and berries are rich in polyphenols, compounds that can positively impact BDNF production.
• Whole grains: Consuming oats, rice, and corn can contribute to increased levels of BDNF, providing essential nutrients that support brain health.
• Omega-3 fatty acids: Found in fishes like salmon and plant-based sources like flaxseed, omega-3 fatty acids are known to enhance BDNF production and promote neural resilience.
• Flavonoid-rich foods: Dark chocolate and tea contain flavonoids that have been linked to improvements in brain function and potential increases in BDNF levels.
• Spices and herbs: Ingredients like turmeric, which contains curcumin, and rosemary have also been studied for their neuroprotective properties and potential to elevate BDNF.
• Leafy greens and vegetables: Foods like spinach, kale, and broccoli provide antioxidants and nutrients that can influence brain-derived neurotrophic factor levels positively.

Incorporating these dietary elements into daily meals not only supports brain health but also builds resilience against conditions like depression. Dietary strategies, when combined with regular physical activity, may offer a holistic approach to improving BDNF levels naturally.

The Challenges and Future of BDNF Research

While there are apparent links between BDNF and depression, further work is still needed to fully define this pathophysiology. This is due to the multivariate factors that can impact depression. Although research studies point to the treatment possibilities of probiotics, diet, and exercise, the use of these interventions as a general strategy is limited by differences in personal responses. Gut microbiomes and responses to dietary changes or exercise regimes can vary greatly from person to person.

BDNF’s role in depression and brain health is a rapidly expanding field of study. Understanding the connection between BDNF and depression may unlock new pathways for treatment. At any rate, given the ever-increasing prevalence of depression within the population, it is important to pursue all avenues that could contribute to the development of efficacious treatments. Brain-derived neurotrophic factor (BDNF), with its profound impact on neuronal health, signaling, and growth, remains at the forefront of research into how to increase BDNF and its therapeutic potential for mental health.