Isn’t it fascinating how food and lifestyle decisions can impact brain health and memory? One of the molecules that’s top of mind for me is Brain Derived Neurotrophic Factor (BDNF), which I’ve heard referred to as ‘Miracle Gro for the Brain’.
Let’s start with a breakdown of the word ‘Neurotrophic’: From Nature: “Neurotrophic factors are molecules that enhance the growth and survival potential of neurons. They play important roles in both development, where they can act as guidance cues for developing neurons, and in the mature nervous system, where they are involved in neuronal survival, synaptic plasticity and the formation of long-lasting memories”. (Source)
Some roles of BDNF are:
- Learning & Memory: BDNF plays an important role in the survival, maintenance and growth of many types of neurons and is expressed abundantly in the hippocampus, hypothalamus, and cerebral cortex, while also playing a role in long-term memory (Source). There is solid evidence that hippocampal BDNF expression, in response to spatial memory training, is associated with memory performance. (Source)
- Food regulation: In mouse models without BDNF (conditional BDNF knockout mice), neurons that regulate food intake in the ventromedial hypothalamus via the thrombospondin receptor a281 are reduced, while increased receptor action has been seen to reverse increased food intake and to improve glucose tolerance. These findings have led researchers to think that BDNF may have a protective role against the progression of obesity. (source)
- Mood: Brain-derived neurotrophic factor (BDNF) plays an essential role in neuronal plasticity, with the downregulation of BDNF expression/function reproduced in a variety of animal models of depression. BDNF malfunction has been implicated in the pathology of neurological and psychiatric disorders, while nutritional status has been shown to affect critical pathways involved in depression through both BDNF function and the monoamine system. (source)
If you’re saying ‘yes, please, more BDNF!’, here are some foods and food compounds to focus in on:
- Turmeric: this colorful yellow root has been tied to all kinds of health benefits including improved mood and decreased risk for Alzheimer’s disease. Curcumin, the oft-discussed bioactive compound that comes from turmeric root, has been shown to increase levels of BDNF in the hippocampus and prefrontal cortex (source).
- Zinc: is a micronutrient found in higher amounts in oysters, red meat and poultry, eggs, legumes, nuts, seeds, and soy. In one study, a group of 46 overweight or obese subjects were given 30mg zinc or placebo daily for 12 weeks, with findings that BDNF levels increased significantly in the supplemented group. At the beginning of the study, there was already a positive correlation between serum BDNF and serum Zinc levels at baseline (meaning those with higher blood zinc levels also had higher measured BDNF levels) (source). However, high-dose supplementation with Zinc in animal models has been found to induce a zinc deficiency in the hippocampus through impaired synaptic zinc release signaling (source). Think ‘food first’ with zinc intake to play it safe.
- Cacao: In one trial investigating changes in serum brain-derived neurotrophic factor (BDNF) following flavonoid intake from cocoa, older adults (aged 62-75 y) were given both a high-flavanol cocoa drink (494 mg total flavanols) and a low-flavanol cocoa drink (23 mg total flavanols) for 12 weeks. Intake of cocoa flavanols were paralleled by concurrent changes in serum BDNF levels, suggesting a role for BDNF in flavonoid-induced cognitive improvements (source). You’re welcome.
- Other Flavonoid Rich Foods: Evidence suggests that flavonoid-rich foods (such as fruits, vegetables, chocolate, wine & tea) can improve memory and cognition in both animals and humans. Changes in spatial memory have been seen with doses of flavonoids reflective of normal dietary intake [Human equivalent dose (mg/kg): flavanols = 4.75 mg/kg ×(6/37) = 0.77 mg/kg or 54 mg for a 70 Kg adult; anthocyanins = 130 mg for a 70 Kg adult], with increases in hippocampal BDNF protein level accompanied by flavonoid-rich diets (source). Beneficial effects of green tea and Gingko Biloba, other flavonoid rich foods, on spatial memory have been shown to involve increases in hippocampal brain-derived neurotrophic factor (BDNF) (source)
- Blueberry: supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory (source).
- Reduce Sugar: Diets high in fat AND sugar reduce BDNF expression and this has been correlated with memory deficits. Molteni, et al. (source) for example, found reduced hippocampal BDNF mRNA and protein after 2 months, 6 months and 2 years on a high fat and sucrose diet in rats. Although there’s plenty to good to say about the benefits of certain fats for brain health and memory, sugar just doesn’t have the same positive reputation behind it.
- Omega 3 fatty acids: Early exposure to dietary omega-3 fatty acids orchestrates key interactions between metabolic signals and Bdnf methylation creating a reservoir of neuroplasticity that can protect the brain against the deleterious effects of switching to a western diet (WD) (source). In animal models, a high omega-3 diet elevated BDNF levels (both protein and gene) (source).
- Movement: If you are someone who is exercising consistently, you’ve likely already noticed how movement boosts our brain power! BDNF levels even increase after resistance exercise, like weight lifting (source).
- Gut Health and Microbiome Diversity (more to come, I bet!): interestingly, I’ve seen a couple of studies where specific strains of beneficial gut bacteria have been linked to BDNF. In a review of the role of microbiota in depression, a study is referenced where supplementation of Lactobacillus helveticus NS8 restored hippocampal serotonin (5-HT) and norepinephrine (NE) levels, and caused higher expression of hippocampal brain-derived neurotrophic factor (BDNF) mRNA (source).
Does any of this information surprise you? Which of these foods or food components is already making it’s way into your diet? Let me know how you’re using your own diet to boost memory, mood & focus-I’d love to know!