Nutrient Status
Pellagra, scurvy, rickets, beriberi, anemia…depression, anxiety, cognitive deficits?? Whereas the first 5 diseases mentioned are commonly known to be caused by nutritional deficiencies, the last few are rarely thought of in this respect. The physical symptoms of vitamin and mineral deficiencies are well researched and cautioned by all medical professionals, but the cognitive and mental signs of the same deficiencies are only starting to be recognized. Just as the vitamins and minerals found in foods serve physical processes to keep our bodies healthy and functioning well, they also have an enormous impact on our brain and its functioning. Deficiencies in key nutrients are now linked to several cognitive impairments such as mood disorders like depression and anxiety, mental fatigue, (Tardy et al., 2020), executive functions, memory (Denniss, Barker, & Day, 2019), learning, regulation of hunger, attention (Bourre, 2006, b.), and even cognitive decline (Choi et al., 2020). Let’s take a look into the brain to see how this happens.
Nutrients & Brain Structure
The very structure of our brain is made up of the nutrients that we consume. The brain’s structure is: 80% water, 11% fats, 8% proteins, 3% vitamins and minerals, and just a tiny bit of carbohydrates (Bourre, 2006). The brain needs these nutrients to maintain its structure and functioning. Where do the majority of these nutrients come from? Our diet.
As you saw above, the dry weight of our brain (the weight of the brain not including water) is composed mostly of fats . These fats make up the structure of our cell membranes, and are needed for the cell strength, shape, and elasticity (Bourre, 2006, b.) And not just any fats! One out of every three fatty acids found in the nervous system is a polyunsaturated fatty acid (Bourre, 2006, b), a type of essential fat, meaning that our bodies cannot produce them on their own, so we must get them from our diets. The two main types of polyunsaturated fats that are found in the brain are Omega-3s and Omega-6s. Omega-3’s can be found in fatty fishes like salmon, sardines, mackerel or cod. Omega-6s are found in walnuts, pumpkin seeds, or sunflower seeds.
Proteins, once broken down, are used by the brain to form neurotransmitters, the brain’s messenger molecules. These neurotransmitters control how you think, learn, remember, feel, even how you sleep (Bourre, 2006). The brain needs a continual supply of dietary protein in order to develop these neurotransmitters. For example, the neurotransmitter serotonin is often referred to as the “happy chemical,” which is low in individuals who suffer from depression. In order to make serotonin, the brain needs the amino acid tryptophan. If you’re living in the United States, you’ve probably heard of tryptophan because of its ability to put you to sleep after Thanksgiving dinner. Animal foods high in protein, like turkey, are high in the tryptophan your brain uses to make serotonin.
Although mainly formed by the protein that you consume, vitamins and minerals are also needed for the synthesis of neurotransmitters. For example, vitamin C acts as a cofactor in the synthesis of neurotransmitters such as noreadrenaline and adrenaline (Travica et al., 2017). Vitamin B1 is needed to form the precursors of neurotransmitters like acetylcholine, glutamate, and gamma-aminobutyric acid. Vitamin B5 is needed for the synthesis of acetylcholine. The synthesis of serotonin and dopamine is dependent on adequate levels of vitamin B6 and B9 (Tardy et al., 2020). And finally, choline is a precursor for the neurotransmitter acetylcholine (Key et al., 2019).
Nutrients & Brain Function
Not only do the nutrients we eat make up the very structure of our brains, but they’re also involved in its proper functioning.
Once digested by the bacteria in your gut microbiome (see the gut blog post to learn more!), carbohydrates are broken down into glucose, which is your brain’s main source of fuel. The brain uses 100mg per minute of glucose to carry out its normal functions like fueling the electrical impulses that spin our neurotransmitters into action, which in turn regulate everything we do (Bourre, 2006). This is why the brain has very little carbohydrates in its “structure.” The carbs that make their way up to the brain are quickly used up for energy.
Vitamins and minerals serve important roles in our brain and our cognitive functioning. According to Bourre (2006), it may even be possible to assign a specific efficacy to each individual vitamin for certain functions within the brain. The foremost function in which many vitamins and minerals serve is that of energy production in the brain. The ability of the cells in the brain to produce energy (from the glucose mentioned above) depends on the availability of several nutrients such as B vitamins, vitamin C, magnesium, and iron (Tardy et al., 2020). Without any one of these nutrients present in its required amount, the entire energy metabolism process can be slowed down.
Remember inflammation? That cognitive disrupter we learned about a few weeks ago (check out this blog post to learn more)? And how it can be driven by oxidative stress in the brain? Because the brain requires a lot of oxygen to perform its functions, it is at risk for oxidative stress, if certain micronutrients aren’t available as an antioxidant defense system. For example, Vitamin B2 serves a protective role against lipid peroxides (Tardy et al., 2020). This is important because as we know, the brain is made up largely of lipids (fats), and with its high consumption of oxygen, these lipids are at risk for oxidation. Vitamin C is another potent antioxidant that can help to fight oxidative stress in the brain, and a deficiency in this vitamin may cause oxidative stress and neurodegeneration (Ballaz & Rebec, 2019). Vitamin E and its antioxidant effects can also play a protective role of the polyunsaturated fats found in the membrane of the neuronal structures, such as the brain (Tardy et al., 2020). Vitamin K is also protective against oxidative stress and inflammatory cascades in the brain (Alisi et al., 2019). Low levels of magnesium can lead to inflammation, which can increase the amount of reactive oxygen species (ROS) produced in the brain (to learn more about this, see this blog post), which may lead to oxidative stress. Finally, zinc has antioxidant properties that help to reduce the production of ROS in the brain.
Neurotransmitters function by traveling between cells and attaching to their specific receptors on other cells. Their ability to execute this function properly is dependent on several vitamins and minerals. Vitamins B3, B5, C, and minerals such as calcium, iron, magnesium, and zinc can all modulate neurotransmitter functioning (Tardy et al., 2020).
Nutritional Deficiencies in Cognitive Function
Because each nutrient serves its own function within the nervous system, it probably comes as no surprise to find out that deficiencies in each nutrient result in various cognitive impairments. There are at least 30 different nutrients that your bodies and brains need to function optimally, so we won’t go into detail about how a deficiency in each one can impact the brain. Instead, I’ll highlight a few where deficiencies are common, and the results can be largely detrimental to cognitive performance.
Vitamin B1 (Thiamine): chronic deficiency in this nutrient can lead to the disease called beriberi, which is characterized by severe cognitive impairment, including a profound memory disorder. Although these cases are extreme and rare in developed countries, individuals can still experience subtle cognitive symptoms such as memory impairments, diminished learning, lowered intelligence, and reduced neurogenesis with only subclinical (meaning not yet characterized as a “deficiency” by doctors) thiamine deficiency (Bourre, 2006, Tardy et al., 2020).
Vitamin B3 (Niacin): long-term deficiency in this nutrient can lead to symptoms of depression and loss of memory (Tardy et al., 2020).
Vitamin B12: deficiency in this vitamin can occur even before blood concentrations reach “deficient” criteria, and can cause progressive neuronal degeneration. This can manifest as irritability, memory loss, and depression (Tardy et al., 2020).
Vitamin C: deficiency has been associated with impaired cognitive functions in tasks involving attention, working memory and recall, decision speeds, and recognition (Travica et al., 2019).
Vitamin D: deficiency in this vitamin may be linked to cognitive decline and dementia (Sultan et al., 2020).
Vitamin K: there has been shown to be a correlation between lower levels of this vitamin and cognitive decline associated with aging. In 6 studies, there was a direct correlation between low vitamin K intake and deteriorated cognitive and behavioral performances (Alisi et al., 2019).
Iron: because iron is necessary for oxygen transport to the brain and the modulation of neurotransmitters within the brain, deficiency in this mineral can cause disruptions in cognitive functioning. Anemia (iron deficiency) has been linked to lower levels of attention, responsiveness, and overall cognitive performance (Kumar et al., 2019).
Magnesium: this mineral is responsible for over 300 enzymatic reactions in the body, so its deficiency can result in a plethora of impairments. However, one noteworthy impairment due to magnesium deficiency is the increased susceptibility to stress disorders (Pickering et al., 2020).
Zinc: deficiency can be linked to degenerative diseases such as Alzheimer’s, changes in behavior and mood as seen in depression and anxiety, reduced neurogenesis, and impaired learning and memory (Choi et al., 2020).
What’s important to note is that the cognitive impairments that are linked to several of these nutrients can appear even before blood levels reach a threshold of “deficient.” What this means is that even if your bloodwork is not showing that you’re deficient in any nutrients, you may not have levels optimal to support your overall brain functioning. Keep this in mind as you read the suggestions below!
Ditch the Pills, Eat the Food
As you can see, the brain relies on optimal levels of several different nutrients for its optimal functioning. Unfortunately, 92% of Americans are deficient in at least one micronutrient. In today’s food environment, it’s easy to be! The processed foods that make up over 60% of our typical Western Style Diet are devoid of any nutrients that our bodies and brains need. We are filling ourselves up with processed foods and all the while starving our brains of the very nutrients it needs to function properly. As you know, my philosophy is Food First. I believe there is a time and place for supplementation, but the nutrients found in foods are much better absorbed and utilized by the body. Also, over supplementing with certain nutrients such as iron can actually damage the brain by way of oxidative stress (Carocci et al., 2018).
That being said, here are some ways to ensure you’re getting plenty of vitamins and minerals from your diet alone. If you are deficient in one or more nutrients (as defined by lab results) please work with your healthcare practitioner or nutrition coach to determine if supplementing may be right for you.
Eat the Rainbow: and no, I don’t mean skittles. Every week, try and eat a whole food from as many color groups as you can. Different colored foods contain different nutrients, so by eating the rainbow, you’re getting a wide variety of nutrients every week!
Ditch the Meal Prep: you heard that right, a nutrition coach against meal prep! By eating the same foods day in and day out, you’re getting the same nutrients. Instead, diversify the foods you’re eating! If you had a chicken salad for lunch yesterday, maybe a tofu stir fry today. If you had grass-fed beef and broccoli for dinner last night, try baked salmon with roasted veggies tonight! Try and add in as many different plant and quality animal products as possible in every given week.
Cut Out Processed Foods: as I said above, processed foods are high in calories, but devoid of any nutrients that our bodies need. If you’re eating a highly processed food diet, you’re going to be over-feeding your body but also starving it of nutrition at the same time!
Eat Enough: restrictive dieting can, in some cases, cause nutritional deficiencies because the individual is not getting enough nutrients. Although it is important to look at calories when trying to lose weight, do not restrict to the point where your body isn’t getting what it needs to function properly.
References
Alisi, L., Cao, R., de Angelis, C., Cafolla, A., Caramia, F., Cartocci, G., Librando, A., & Fiorelli, M. (2019). The Relationships Between Vitamin K and Cognition: A Review of Current Evidence. Frontiers in Neurology, 10. https://doi.org/10.3389/fneur.2019.00239
Ballaz, S. J., & Rebec, G. V. (2019). Neurobiology of vitamin C: Expanding the focus from antioxidant to endogenous neuromodulator. Pharmacological Research, 146, 104321. https://doi.org/10.1016/j.phrs.2019.104321
Bourre, J. M. (2006). EFFECTS OF NUTRIENTS (IN FOOD) ON THE STRUCTURE AND FUNCTION OF THE NERVOUS SYSTEM: UPDATE ON DIETARY REQUIREMENTS FOR BRAIN. PART 1: MICRONUTRIENTS. The Journal of Nutrition, Health, and Aging, 10(5).
Carocci, A., Catalano, A., Sinicropi, M. S., & Genchi, G. (2018). Oxidative stress and neurodegeneration: the involvement of iron. BioMetals, 31(5), 715–735. https://doi.org/10.1007/s10534-018-0126-2
Choi, S., Hong, D. K., Choi, B. Y., & Suh, S. W. (2020). Zinc in the Brain: Friend or Foe? International Journal of Molecular Sciences, 21(23), 8941. https://doi.org/10.3390/ijms21238941
Denniss, R. J., Barker, L. A., & Day, C. J. (2019). Improvement in Cognition Following Double-Blind Randomized Micronutrient Interventions in the General Population. Frontiers in Behavioral Neuroscience, 13. https://doi.org/10.3389/fnbeh.2019.00115
Key, M. N., Zwilling, C. E., Talukdar, T., & Barbey, A. K. (2019). Essential Amino Acids, Vitamins, and Minerals Moderate the Relationship between the Right Frontal Pole and Measures of Memory. Molecular Nutrition & Food Research, 63(15), 1801048. https://doi.org/10.1002/mnfr.201801048
Kumar, S., Agrawal, S., Ingole, V., Acharya, S., Wanjari, A., Bawankule, S., & Raisinghani, N. (2019). Does anemia affects cognitive functions in neurologically intact adult patients: Two year cross sectional study at rural tertiary care hospital. Journal of Family Medicine and Primary Care, 8(9), 3005. https://doi.org/10.4103/jfmpc.jfmpc_599_19
Pickering, G., Mazur, A., Trousselard, M., Bienkowski, P., Yaltsewa, N., Amessou, M., Noah, L., & Pouteau, E. (2020). Magnesium Status and Stress: The Vicious Circle Concept Revisited. Nutrients, 12(12), 3672. https://doi.org/10.3390/nu12123672
Sultan, S., Taimuri, U., Basnan, S. A., Ai-Orabi, W. K., Awadallah, A., Almowald, F., & Hazazi, A. (2020). Low Vitamin D and Its Association with Cognitive Impairment and Dementia. Journal of Aging Research, 2020, 1–10. https://doi.org/10.1155/2020/6097820
Tardy, A. L., Pouteau, E., Marquez, D., Yilmaz, C., & Scholey, A. (2020). Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence. Nutrients, 12(1), 228. https://doi.org/10.3390/nu12010228
Travica, N., Ried, K., Sali, A., Scholey, A., Hudson, I., & Pipingas, A. (2017). Vitamin C Status and Cognitive Function: A Systematic Review. Nutrients, 9(9), 960. https://doi.org/10.3390/nu9090960
Travica, N., Ried, K., Sali, A., Hudson, I., Scholey, A., & Pipingas, A. (2019). Plasma Vitamin C Concentrations and Cognitive Function: A Cross-Sectional Study. Frontiers in Aging Neuroscience, 11. https://doi.org/10.3389/fnagi.2019.00072