I’m sure you’ve heard it before: we are holistic beings, and our bodies and minds are connected in many complex and important ways. The brain is an excellent example of this interconnectedness. As you may have seen in our previous article about brain health, if your brain is unhealthy, it can affect your mind, body, and even your personality. The body can affect the brain too, and we recently focused on the effects of high blood sugar and insulin resistance on brain health. Nutrition and hormones are another two key factors that can affect your brain and mental health at every stage of life.
Nutritional effects make sense, but how can hormones affect your brain? Don’t we usually hear about them in relation to reproduction?
While hormones certainly play a starring role in our reproductive systems, they also have a huge effect on brain health. Humans have many different types of hormones in our bodies, influencing everything from mental health and stress levels to reproductive and even gut health. Insulin is actually a hormone, and its correlation to brain health is talked about in-depth in this article. “Happy hormones” that are also neurotransmitters, such as oxytocin, endorphin, and serotonin are widely known to contribute to brain function, happiness, and overall mental and brain health (1).
Perhaps less well-known as brain health influencers are steroid hormones, which are a set of hormones that contain both glucocorticoids (cortisol) and sex hormones (estrogen, testosterone, etc.) (2).
What are glucocorticoids?
Glucocorticoids, of which cortisol is the most well-known, are released in response to stressful situations. They work quickly to alter both the body and brain’s responses to create optimal performance during a stressful event (3). If stress is experienced too often, cortisol levels can end up either severely elevated or lowered, meaning weakened synapses, altered dendritic branching, and overall lowered mood, functioning, and psychological health (3, 4). Unfortunately, this can also lead to impaired memory in both children and adults and can contribute to the development of dementia and Alzheimer’s disease as we grow older (4).
How can hormones like estrogen and testosterone affect the brain?
Sex hormones, including estrogen, progesterone, testosterone, and androstenedione, are all key factors that can prevent cognitive decline and mental health problems. Both men and women produce all four of these hormones, in varying amounts. These hormones may all act as neuroprotectors, exhibiting powerful antioxidant properties and increasing neural function, resilience, and survival (4). When sex hormone levels decrease due to age, menopause, or other factors, the decrease is correlated with an overall drop in neural function, and more specifically can lead to mitochondrial and synaptic dysfunction, neuroinflammation, and an increased risk of age-related cognitive disorders (4).
Effects of the “maternal hormones,” estrogen and progesterone, on the body and brain are crucial. Estrogen contributes to memory, emotional function, cognition through stimulating neuron growth and neuroplasticity, and even offers some protection for the brain during a stroke (4). Estrogen can increase blood flow and glucose uptake in the brain, improving overall brain energy metabolism (5). BDNF (brain-derived neurotrophic factor), which plays a crucial role in neurotransmitter modulation as well as neuronal survival, growth, and overall plasticity, is also associated with healthy female sex hormone levels (5).
Large fluctuations in these hormones are correlated with reduced verbal memory, attention, and processing skills - thus contributing to conditions like “pregnancy brain”! Outside of pregnancy, hormone changes across the menstrual cycle can cause changes in brain reactivity, leading to slight but sometimes perceptible differences in cognitive ability in some women (4). The effects of hormonal fluctuation in women long-term could account for why there are higher instances of and faster decline in neurodegenerative diseases like Alzheimer’s (4, 5).
Androgens like testosterone and androstenedione play a lot of the same roles: they regulate, repair, and support neuron health, are neuroprotective, and healthy levels within men are even correlated with a reduced risk of prostate cancer (5). Similarly, their decline over time also correlates with reduced cognitive performance as well as lowered BDNF expression (5).
So, how does all of this relate to nutrition?
If you’ve heard about the “Western” or “Standard American Diet”, you know that it is high in sugar and unhealthy fat. Unfortunately, it is being linked to a host of problems, including obesity, diabetes, heart disease, stroke, high blood pressure, and the focus of this article: nutritional and hormonal deficiencies.
How is nutrition linked to my brain and hormones?
Since most micronutrients are used in brain functioning, it is important that we provide our brains with a variety of micronutrients through a varied and well-rounded diet (6). In terms of hormones, a poor diet may affect hormonal expression and levels directly (7). If we have an unhealthy gut through poor diet and don’t get enough nutrients, both brain and hormonal function can be impaired and result in lowered cognitive functioning (8). This is especially true for both children and the elderly, as exposure to a high fat and sugar diet during childhood and later in life produces more drastic cognitive deficits than in adults with a poor diet (8).
Indeed, adequate intake of dietary nutrients is actually protective against cognitive impairment (8). Good nutrition is key for children to achieve their full genetic potential for physical and mental growth and development. Even mental and behavioral functions can be compromised if children experience nutritional deficiencies (6). In fact, the standout feature of the diets of those who suffer from the most common mental illnesses such as depression, bipolar disorder, schizophrenia, and OCD is the severity of their deficiencies in vitamins, minerals, and omega-3 fatty acids. Nutritional supplementation is becoming more prevalent as a treatment option to both prevent and cope with mental illnesses (9). Amino acid supplements and multivitamins can reduce symptoms of mental illness, and overall stimulate a better and more even mood (9, 10).
So, which nutrients and foods are the most important for brain health?
The nutrients listed below are the most critical to keep your brain healthy at all ages and stages of development. However, as highlighted below, their individual importance varies over our lives as our needs change from our initial fetal development all the way to our old age.
Omega-3 fatty acids support cognitive function, including synaptic function and plasticity, and are crucial to fetal and infant brain development. In adults, they can create antidepressant effects and even effectively treat depression. The best sources are fish (especially salmon) and krill, chia and flax seeds, kiwi, and walnuts (11).
Vitamin B1, B2, B6, and B12 have positive effects on memory performance and cognition of all ages and, for the elderly especially, are a critical part of the synthesis of neurotransmitters, delayed onset of dementia, and improved language function. B vitamins are widely available in many foods with the best sources being whole grains, all types of lean meats, eggs and dairy, legumes, dark, leafy vegetables, and fruits like avocados, citrus, and bananas (11, 12).
Calcium and Vitamin D may prevent dementia, inflammation, neurodegenerative and neuroimmune diseases, diabetes, and depression. In fetuses, adequate vitamin D levels may prevent future mental illnesses such as schizophrenia, autism, and learning and memory disorders (11, 13). Great sources are fatty fish, mushrooms, fortified products, milk, soy milk, and cereal grains (11).
Vitamin E can help improve memory as we age and delay overall cognitive decline through protecting synapses and supporting synaptic plasticity. Vitamin E is found in asparagus, avocado, spinach, olives, peanuts and tree nuts, seeds, and vegetable oils (11).
Iron can improve depression and normalize cognitive function in women of all ages. Low levels of iron in the umbilical artery can affect brain development, cognition, and the IQ of developing children in utero. The best sources of iron are in red meats, fish, poultry, lentils, and beans (11). <