Fish oil and its importance for brain development

Oily fish and fish oil contain the long-chained omega-3 fatty acids, EPA and DHA, that are of vital importance to the brain, the nervous system, and our mental health throughout life. Today, most people on a global scale lack these omega-3 fatty acids because of altered dietary habits, including the use of unnatural animal fodder. Low intake of omega-3 increases the risk of various ailments such as ADHD, autism, depression, borderline personality disorder (BPD), and bipolar disorder. Fish oil supplementation may therefore offer promise as prevention and part of the therapy used to treat a number of these disorders. The problem with modern diets is their disproportionate content of omega-6 at the expense of omega-3, an imbalance that may derail a number of physiological functions of importance to our mental health, according to a review article published in the science journal, Nutrients.

Both omega-3 and omega-6 fatty acids are found in our cell membranes, where they are part of an intricate biochemical interplay, in which the ratio of the different fatty acids is vital. Human and animal brains contain rather large amounts of these two fatty acids that help secure integrity in the neurological network. Through millions of years, our ancestors have ingested a substantial amount of the essential omega-3 fatty acids, EPA and DHA, from sources like oily fish, shellfish, and other types of seafood. It is believed that the average daily intake of omega-3 in the early stone age or the lower Paleolithic period (from around 2.6 million years BC to around 10,000 years BC) was 660-14,250 mg. Just for the sake of comparison, the current intake is around 100-200 mg.
Moreover, prehistoric humans did not get as much as omega-6 as we do now, but it is especially within the last hundred years or so hat the omega-6 intake has skyrocketed. This is primarily because of our high intake of plant oils from soy, corn, sunflower, and safflower that are all rich in omega-6. Margarine, deep-fried foods, ready meals, and junk-food also provide a lot of omega-6. Because of this, the omega-6/omega-3 ratio has changed from 4:1 (during the stone age) to 20:1, and it is especially the modern diets, changes in farming methods, and the industrialization that has contributed to this imbalance.

DHA and its role for infant development

DHA is a very long-chained fatty acid and is particularly important for the development of the child’s brain, central nervous system, and vision. In fact, this particular fatty acid is believed to have contributed to the high intelligence of humans. According to The International Society for the Study of Fatty Acids and Lipids, pregnant and breastfeeding women should make sure to get at least 300 mg of DHA every single day. Unfortunately, the current average intake today is only about 60-80 mg. The unborn child has a particularly great need for DHA during the last months of pregnancy, and premature babies are unable to store DHA from their mothers. The child also needs large quantities of DHA during the first 5-10 months after birth, which is why breastmilk is a rich source of DHA. The problem is that baby formula often only contains the form of omega-3 called ALA (alpha-linolenic acid), which it is difficult for the child to convert into DHA.
Lack of DHA during the period of fetal development and in early childhood may impair the child’s lingual skills, social behavior, and cognitive skills. The authors behind the new article in Nutrients specifically address that DHA is important for brain neurons and synapses, where information is shared by neurons. DHA is also important for the production of neurotransmitters such as acetylcholine, dopamine, serotonin, glutamate, and GABA. Many of these neurotransmitters are of vital importance for learning skills and a good mood.
A lot of scientific studies and data reveal that supplementing with EPA and DHA during pregnancy benefits the early stages of child development. On the market, you are able to find special supplements for pregnancy that combine these essential fatty acids.

ADHD

ADHD (Attention Deficit Hyperactivity Disorder) affects up to 15% of American school children, and the disease usually follows them into adulthood. Studies show that children and adults with ADHD have lower levels of DHA in their cell membranes, which is lined to their learning difficulties, hyperactivity, impulsive behavior, anxiety and sleep problems. A Japanese double-blind, placebo-controlled study of 40 children suffering from ADHD showed that daily supplementation with 500 mg of DHA and 100 mg of EPA improves ADHD symptoms. Other studies show similar results. The authors behind the Nutrients article therefore conclude that supplementation with long-chained omega-3 fatty acids from fish oil may help reduce ADHD symptoms.

Autism

Autism is characterized by grave disturbances in behavior, communication, and social interaction. Studies show that children with autism have reduced levels of EPA and DHA in plasma and in the membranes of their red blood cells. A double-blind, randomized, controlled study of autistic children in the age group 5-17 years reveals that daily supplementation with 1,540 mg of EPA/DHA had a positive effect on their condition.

Depression and anxiety

More and more people in the Western world are affected by depression. It is assumed that 30-40 percent of patients don’t benefit from their medical treatment and may have side effects. According to the scientist behind the article in Nutrients, depression may be a result of getting to little omega-3 and too much omega-6. A Dutch study published in the journal Psychoneuroendocrinology shows that patients suffering from a combination of depression and anxiety had lower omega-3 levels than patients that only suffered from depression. The lack of DHA may affect the nervous system and the production of neurotransmitters such as dopamine and serotonin that are essential for a good mood and a positive outlook.
Studies show that supplementation with omega-3 fatty acids can help against depression. The same goes for postpartum depression (“baby blues”), Parkinson’s disease, and bipolar disorders.

Depression and inflammation

The imbalance between omega-3 and omega-6 may lead to brain inflammation. Elevated levels of proinflammatory markers have been observed in depressive patients, and these markers are associated with the severity of the depression. However, anti-depressive drugs do not address brain the problems with brain inflammation that may be the root cause of depression. Supplementing with omega-3, on the other hand, may have a positive effect on a depression, and it turns out that EPA is particularly effective when it comes to inhibiting inflammation. When supplementing, one must strive to get around 1,000 mg of EPA daily, according to a study from Harvard University.

Borderline disorder

Borderline disorder is the most commonly diagnosed personality disorder. People often have impulsive behavior and act without any filter, and their emotions fluctuate violently. Also, you see problems like depression, anger, anxiety, insecurity and low self-esteem and sensitivity to criticism. A double-blind, placebo-controlled study has shown that supplementing with 1,000 mg of EPA daily may reduce aggression and the severity of the depression.

Alzheimer’s disease and dementia

Numerous epidemiological studies have revealed that a low intake of omega-3 fatty acids is linked to age-related loss of cognitive skills and Alzheimer’s disease, the leading cause of dementia. Scientists have also found a link between brain inflammation and the development of Alzheimer’s. Increased intake of EPA and DHA may help prevent both Alzheimer’s disease and dementia, according to many epidemiological studies.

References:

James J. Dicolantonio and James H. O´Keefe. The Importance of Marine Omega-3s for Brain Development and the Prevention and treatment of Behavior, Mood, and Other Brain Disorders. Nutrients. 2020

Carisha S. Thesing et al. Omega-3 and omega-6 fatty acid levels in depressive and anxiety disorders. Psychoneuroendocrinology. 2018

Rapaport MH et al. Inflammation as a predictive biomarker for response to omega-3 fatty acids in major depressive disorder: a proof-of-concept study. Molecular Psychiatry 2015

Robert M. Carney et al: Baseline Blood Levels of Omega-3 and Depression Remission: A Secondary Analysis of Data From a Placebo-Controlled Trial of Omega-3 Supplements. Journal of Clinical Psychiatry. 2016

Rapaport MH et al. Inflammation as a predictive biomarker for response to omega-3 fatty acids in major depressive disorder: a proof-of-concept study. Molecular Psychiatry 2015

Nutrition insight. Neuroimaging Highlights Role of Omega-3 in preventing Cognitive decline. 2017

Greb M. Cole et al. Omerga-3 fatty acids and dementia. Prostaglandins, leukotrienes, and essential fatty acids. 2009

Else Kjørstad. Hvor sundt er opdrættet laks? Videnskab.dk 2019