While some people may not be concerned with the plight of polar bears or the destruction of rainforests, no one wants to suffer from diminished brain capacity. Unfortunately, the latest research suggests that burning fossil fuels may increase the chances of brain damage. Particulates found in air pollution from burning fossil fuels may lead to brain dysfunction. Additionally, elevated carbon dioxide (CO2) levels will likely reduce plant nutrition leading to cognitive and emotional difficulties.
The theory is new and has not yet reached full scientific consensus. And indeed, not all cases of brain dysfunction are caused by elevated CO2 and air pollution. However, all of the following information comes from respected scientific journals.
Air pollution from burning fossil fuels might be a contributing factor in the rising prevalence of diabetes. Diabetes increases the risk for both brain-damaging strokes and Alzheimer’s. The article “Carbon Dioxide Emissions and Change in Prevalence of Obesity and Diabetes in the United States: An Ecological Study” was published in Environment International. The authors stated that a recent study found a significant relationship between county levels of PM2.5, one of the particulates found in air pollution, and the prevalence of diabetes.
Moreover, air pollution limits the ability of human skin to synthesize vitamin D leading to an increased risk of vitamin D deficiency. This was shown in “The Effects of Air Pollution on Vitamin D Status in Healthy Women—A Cross Sectional Study”, published in BMC Public Health.
And vitamin D deficits can lead to brain dysfunction. Low gestational vitamin D levels are associated with an increased risk for attention-deficit/hyperactivity disorder. This was shown in “Maternal Vitamin D Levels and the Risk of Offspring Attention-Deficit/Hyperactivity Disorder”, published in the Journal of the American Academy of Child & Adolescent Psychology.
Mothers with lower gestational levels of vitamin D are also more likely to have a child with autism. This was shown in “Lower Maternal Serum 25 (OH)D in First Trimester Associated with Higher Autism Risk in Chinese Offspring”, published in the Journal of Psychosomatic Research. Similar results were found in “Maternal Vitamin D Deficiency and the Risk of Autism Spectrum Disorder: Population-based Study”, published in The British Journal of Psychiatry. The authors reported that a recent study demonstrated lower neonatal vitamin D levels in children with autism spectrum disorder than their siblings.
Various other mental disorders have also been associated with low vitamin D levels. “The Role of Vitamin D in Brain Health: A Mini Literature Review” was published in Cureus. This meta-analysis found lower vitamin D levels increased the risk for dementia and several studies find a link between vitamin D and depression.
Older adults are at risk of losing cognitive function because of lower vitamin D levels. The article “Identification of Neuroprotective Factors Associated with Successful Ageing and Risk of Cognitive Impairment Among Malaysia Older Adults” was published in Current Gerontology and Geriatrics Research. The authors found that the risk of mild cognitive impairment was reduced when vitamin D levels were higher.
Vitamin D deficiency is associated with greater than twice the odds of all types of dementia, Alzheimer’s and strokes. This was found in “Cognitive Consequences of Vitamin D Deficiency”, which was published in Practical Neurobiology.
Besides fossil fuel air pollution negatively affecting nutrition, increasing levels of atmospheric CO2 will likely damage the nutritional value of essential food crops. The article “Rising CO2 and Human Nutrition: Toward Globally Plant Stoichiometry” was published in Trends in Ecology & Evolution. The paper reported that “every terrestrial plant is exposed to 30% higher [CO2] relative to pre-industrial times; during this century [CO2] levels could double or triple over pre-industrial levels.”
Rising CO2 levels have been found to lower the amount of minerals found in plants. For example, higher levels of CO2 decrease the amount of boron found in leaves and roots, as reported in “Elevated CO2 Affects Plant Responses to Variation in Boron Availability”, published in Plant and Soil. And lower dietary boron has been found to cause significantly poorer performance on tasks emphasizing manual dexterity, eye-hand coordination, attention, and short and long-term memory.
Zinc levels in plants are also affected by rising CO2 levels. The article “Effect of Increased Concentrations of Atmospheric Carbon Dioxide on the Global Threat of Zinc Deficiency: A Modelling Study”, published in The Lancet, reported that “increasing concentrations of atmospheric carbon dioxide lower the content of zinc and other nutrients in important food crops.” This could lead to global zinc deficiencies.
The importance of zinc was also stressed in the article “Zinc Deficiency and Its Effect on the Brain: An Update” published in the International Journal of Molecular Genetics and Gene Therapy. The authors found that zinc deficiency was associated with neurological disorders, mental development, learning disabilities, autism depression, alcoholism, and schizophrenia.
Higher levels of CO2 also lead to lower iron levels in plants and iron deficiency can lead to brain dysfunction. The article “Long-term Brain and Behavioral Consequences of Early Iron Deficiency” was published in Nutrition Reviews. The authors reported “Multiple studies demonstrate long-term motor cognitive and socio-emotional behavioral deficits in children and young adults following a period of ID [iron deficiency] early in life. … formerly iron deficient children demonstrate more anxiety-depression symptoms at 11 to 14 years of age … children born to iron deficient mothers are more likely to develop schizophrenia later in life in a dose-dependent manner related to the degree of maternal ID.”
Elevated CO2 levels may also lower the amount of protein synthesized by plants. And the lower levels of protein in rice is especially catastrophic as it is the global primary food source for more than two billion people. The article “Global Health Implications of Nutrient Changes in Rice Under High Atmospheric Carbon Dioxide”, published in GeoHealth, warned that globally, by 2050, 132 million are a risk for folate deficiency, and 67 million at risk of thiamin deficiency.
Another nutrient necessary for proper brain functioning is Docosahexaenoic Acid (DHA). The article “Projected Declines in Global DHA Availability for Human Consumption as a Result of Global Warming” reported that DHA is an essential omega-3 fatty acid that is usually obtained from consuming fish. Higher water temperatures are predicted to reduce the synthesis of DHA by the algae which is later consumed by fish. Less DHA production will be detrimental to health.
One consequence of lowered DHA consumption is shown in “Maternal Seafood Consumption in Pregnancy and Neurodevelopmental Outcomes in Childhood (ALSPAC [Avon Longitudinal Study of Parents and Children] study): An Observational Cohort Study” published in The Lancet. The authors reported that the lowest maternal seafood intake during pregnancy was associated with lower verbal intelligence, plus an “increased risk of suboptimum outcomes for prosocial behaviour, fine motor, communication, and social development scores.”
Psychological health is critical, and being overweight is an emotional burden for millions. Rising levels of CO2 might be linked with obesity. Again, this is a new theory and is not yet part of the scientific consensus. However, there is a growing body of evidence that indicates the validity of this new theory.
The article “A Proposed Potential Role for Increasing Atmospheric CO2 as a Promoter of Weight Gain and Obesity” reported that over the past two million years, the atmospheric concentration of CO2 remained between 180-280 ppm (parts per million). Therefore, humans evolved to function at much lower CO2 levels than the current level. In the last century, atmospheric CO2 levels were at 280 ppm. According to the US National Oceanic and Atmospheric Administration, the 2020 level was 412.5 ppm.
The effect is worse in industrialized societies, where people spend 80 to 90% of their time indoors and the CO2 level is even higher than the outdoor level.
“Increased CO2 concentration in inhaled air decreases the pH of blood, which in turn spills over to cerebrospinal fluids. Nerve cells in the hypothalamus that regulate appetite and wakefulness have been shown to be extremely sensitive to pH. We hypothesize that an increased acidic load from atmospheric CO2 may potentially lead to increased appetite and energy intake, and decreased energy expenditure, and thereby contribute to the current obesity epidemic.”
In the hypothalamus, “there are specialized nerve cells (orexin neurons), involved in the regulation of appetite, energy metabolism, wakefulness, feeding behaviour and libido. These orexin neurons are extremely sensitive to changes in pH, a decrease of only 0.1 pH units leading to a doubling in their activity. […] Activation of the orexin system will lead to less sleep, and lack of sleep has been reported to decrease levels of the satiety hormone leptin, increase levels of the hunger hormone ghrelin, and alter glucose homeostasis.”
Acidic stress could also lead to the production of cortisol, which increases the risk of obesity. To add to the legitimacy of the theory, “a recent study found that 24 populations of 8 different species, including laboratory animals that had been fed the same diets for decades all displayed significant weight gain.”