Mental Health — Fueling your Brain
Mental health is metabolic health, and nothing screams metabolic health like “mitochondria”. Mitochondria are as relevant to brain health as they are to overall metabolic health and may play a key role in brain disease – neurologic and mental health disorders.
Powering the brain
Mitochondria play many critical roles in the body including being the primary producers of energy in the body – generating 95% of our total energy. They are tiny structures within our cells that are often referred to as the powerhouses of the cell.
Despite the brain representing only 2% of the weight of the body, it uses approximately 20% of its energy.
Because energy utilization is so vital to brain function, our mitochondrial health has profound implications for brain health. Many genetic diseases affecting mitochondrial DNA have been identified, with many of these diseases causing structural changes in the brain as well as a variety of neurologic symptoms. In addition, more than half of individuals with mitochondrial diseases also have psychiatric disorders.
Mitochondrial dysfunction has been identified in several neurologic diseases including autism, ADHD, Alzheimer’s Disease, Parkinson’s Disease, schizophrenia, and depression.
Nutrients for the Brain
We’ve talked about the importance of nutrition for proper brain functioning. There is abundant evidence that dietary deficiencies can negatively impact brain function.
The brain is composed of primarily fat: 57% fat, 38% protein, 5% carbohydrate.
- 20% of the brain is DHA (an omega-3 FA) – a semiconductor of electricity; not found in plant foods
- Critical to development of the brain cortex in early life
- Believed to serve a key role in evolution to increase the brain/body ratio.
Macronutrients — Fats
Our bodies (and brains) require a plethora of nutrients, some of which must be obtained from our environment – termed “essential” because our bodies cannot synthesize them. There are 8 essential amino acids (from protein) and 2 essential fatty acids (from fat): linoleic acid (omega-6) and alpha-linolenic acid (omega-3).
Alpha-linolenic acid (ALA) can be converted to EPA and DHA, but the conversion is quite inefficient and variable. It’s understood that the conversion pathways are not reliable to meet the high demand for DHA in the developing brain. “There is no evidence of metabolic compensation for low intakes of EPA and DHA”. Thus, it is recommended to consume foods rich in EPA and DHA – seafood (oily fish – mackerel, salmon, sardines, trout), oysters), fortified eggs, or supplements.
There are no good plant sources of EPA and DHA. In fact, the levels of DHA in infant red blood cells, umbilical cord blood, and breast milk are reduced in vegetarians (1/3 lower) and vegans (2/3 lower). Especially in the context of pregnancy, this finding necessitates that vegans/vegetarians consume an omega-3 supplement extracted from algae in order to acquire adequate DHA and EPA.
- Meta-analysis: Individuals who consume meat have lower average depression and anxiety levels than those who abstain from meat (vegans and vegetarians) . Vegans experience higher levels of depression than meat consumers. Note: the higher quality studies showed greater differences than lower quality studies.
Macronutrients — Proteins
The brain requires a continual supply of amino acids in order to produce the appropriate signaling molecules called neurotransmitters, and the quality of the brain proteins and neurotransmitters is influenced by the quality of dietary proteins. In general, animal proteins are more valuable than vegetable proteins. As one example, higher consumption of tofu (soybean proteins) is associated with more cognitive impairment and shrinkage of the brain.
Macronutrients — Carbohydrates
See my prior discussion of the role of glucose in the brain, as well as the impact of insulin resistance on dementia and mental health.
Micronutrients – Vitamins
Normal brain function is dependent on the availability of all the vitamins, and certain vitamins are more clearly involved in specific cell functions within the brain.
Vitamin A is involved in the synthesis of visual pigments as well as differentiation and proliferation of cells in utero. It is also involved in cognition. Vitamin A derived from animal sources is made available in a “ready-to-use” format, whereas plant sources provide only a precursor that then needs to be transformed to a usable form. Vitamin A from animal sources of food is 6 times more efficacious than the provitamin A obtained from vegetables.
Vitamin B1 (thiamine) is critical for brain function due to its role in facilitating its use of glucose. Deficiency of vitamin B1 (beri-beri) can result in lethargy and decreased intelligence, eventually leading to severe pain of the extremities, all of which resolves completely with replacement of the vitamin. Decreased thiamine can also cause Alzheimer’s Disease.
Vitamin B3 (niacin) deficiency causes pellagra, one symptom of which is dementia.
Vitamin B6 is present in the brain at 100x greater levels than in the blood and protects against weakness, irritability, and depression. Higher blood levels of B6 are associated with higher performance with memorization.
Vitamin B9 (folic acid) is critical in pregnancy for development of the nervous system. In the elderly, deficiency of folic acid has a negative impact on intellect and memory.
Vitamin B12 deficiency causes neurological disorders (e.g. memory loss, decreased sensation in the limbs, and pain), psychiatric symptoms, and abnormal blood cell development. B12 is available only via animal products, thereby putting vegans and even ovo-lacto-vegetarians at risk. It may take 3-4 years to develop symptoms, but vegans eventually will become deficient, particularly an issue for children, who may develop cognitive impairment and shrinkage of the brain. Vitamin B6 and B12 intake relates positively to memory performance in both men and women. B12 deficiency is associated with a twofold increased risk of severe depression in women.
Vitamin C (ascorbic acid) levels are associated with cognition in elderly adults.
Vitamin D protects the neurons of the hippocampus and preserves cognition in the elderly.
Vitamin E appears to protect against ageing and dementia.
Micronutrients – Minerals
Iron is critical for proper brain development, and deficiency of iron during early development causes long-term cognitive impairment that persists for the long-term despite iron supplementation. Absorption of dietary iron is highly dependent on the source of iron: humans are able to absorb 25-30% of heme iron but only 2-4% of iron (mineral) from vegetable sources. The bioavailability of iron from foods is also highly dependent on what is consumed with it. For example, tea and coffee decrease iron absorption, whereas orange juice increases it. Animal proteins increase uptake of mineral iron whereas soybean proteins decrease uptake.
Zinc is necessary for the sensations of taste and smell, deficiency of which can lead to a vicious cycle of progressive deficiency typically in elderly individuals by making food less appealing and thus leading to worsening zinc deficiency.
Iodine is critical for early brain development due to its role in thyroid hormone production. Deficiency of iodine or thyroid hormones in utero can cause irreversible mental retardation – cretinism. Iodine deficiency lowers IQ by 10-15 points and also impairs motor function in otherwise healthy people.
Magnesium is involved in all aspects of metabolism and is important for stabilization of cell membranes, such that deficiency of magnesium is known to cause tetany (spasm) of muscles.
Numerous other elements are important to the neurologic system, including Copper, Selenium, Cobalt, and Lithium.
Are we getting enough nutrients?
Probably not. It’s clear that proper nutrition is critical to mental health and performance, as our brains and bodies require a wide variety of nutrients, not only for development, but also for routine functioning and even repair.
In our modern food environment, we are at risk of allowing a lot of nutrients to be displaced from our diets by nutrient-poor processed foods, likely contributing to a nutrient-starved brain and subsequently disorders of brain health.
Thus, we should prioritize nutrient-dense foods to ensure provision of the essential factors for functioning of body and brain.