Physiological function of Docosahexaenoic acid

Overview^[2]

Docosahexaenoic acid (DHA) is the long-chain highly unsaturated omega-3 fatty acid with the longest carbon chain and the highest degree of unsaturation. It is commonly known as "brain gold". An important polyunsaturated fatty acid, DHA is mainly distributed in the gray matter of the human brain, retinal cells, nervous system, breast milk and sperm. It can prevent and treat cardiovascular diseases, invigorate the brain and improve the memory, improve retinal function and improve Eyesight, prevention and treatment of Alzheimer's disease, affecting gene expression, anti-inflammatory and inhibiting allergic reactions and other physiological functions, have broad application prospects in new condiments, high-end food, children's food, health food and medicine industries.

Structure^[1][2]

DHA is usually cis, but it can become trans under the action of certain isomerases. Contains multiple "carbodiene" structures and 5 active methylene groups. These active methylene groups are easily affected by light, oxygen, overheating, metal elements (such as Fe, Cu) and free radicals, resulting in chemical reactions such as oxidation, rancidity, polymerization, and double bond conjugation, resulting in carbonyl compounds. The main fish smelly substance. Pure DHA is colorless, odorless, liquid at room temperature, fat-soluble, easily soluble in organic solvents, but insoluble in water, with a melting point of -45.5 to -44.1, so it can still maintain high fluidity at low temperatures.

The first double bond of DHA appears on the 3rd carbon atom at the methyl end of the fatty acid chain. The unsaturated fatty acid chain contains 22 carbon atoms and 6 unsaturated double bonds, so it is called docosahexaene acid. Because of its larger molecule, it is usually the two-position fatty acid present in triglycerides and phospholipids. Because it is in the second position, it is more conducive to the stability of the entire macromolecular spatial structure.

Physiological function ^[2]

1. Prevention and treatment of cardiovascular diseases

DHA can inhibit the synthesis of cholesterol in the body, increase the excretion of cholesterol, and change the composition of fatty acids in lipoproteins, thereby increasing its fluidity. Therefore, DHA has significant effects in lowering blood lipids, lowering blood pressure, preventing and treating atherosclerosis. DHA can not only inhibit platelet aggregation, prevent thromboxane synthesis, and increase blood fluidity, but also can transform itself into antiplatelet lectin, which can promote vasodilation, increase platelet cell membrane fluidity, improve cell membrane permeability, change cell signal, and regulate The role of Na+-Ca2+ converter and calcium ion channel dynamic balance in cardiomyocytes. Therefore, DHA can prevent the formation of cerebral thrombosis, prevent myocardial infarction, and protect the blood vessel wall.

2. Invigorate brain and improve memory

DHA mainly exists in the gray matter of the human brain, accounting for about 10% of human brain lipids, and it is also a substance necessary to maintain the normal function of the brain. Studies have shown that DHA is an essential substance for the development of the brain and nervous system of infants and young children. Studies have shown that the IQ of breastfed infants is significantly higher than that of non-breastfed infants. One of the main reasons is that breast milk can supplement the infant with sufficient DHA. In the process of brain cell formation, DHA facilitates the extension and regeneration of brain cell protrusions. DHA is an important component of brain cells and cranial nerves, and has a certain relationship with fetal cognition. The lack of DHA can cause fetal cognitive confusion. During the 26-40 weeks of pregnancy, DHA is accumulated in the nerve cells of the central nervous system. Half of it is stored in the infant's brain before the baby is born, and the other half is replenished after the baby is born. In the last 3 months of pregnancy, DHA in the brain increased 3.5 times, and DHA in the brain increased by the same fold within 12 weeks after the baby was born. Given that DHA is an indispensable brain-building substance for human development and growth, countries such as the United States, the European Community, and Japan have enforced the standard that DHA must be added to infant formula milk powder. At the same time, studies have shown that taking DHA has a certain therapeutic effect on Alzheimer's disease.

3. Improve retinal function and improve vision

DHA is an important component of retinal cells. It promotes the growth and development of the brain and vision of fetuses and infants, and it also delays the decline of the brain and vision of the elderly. It occupies more than 60% of the total fatty acid in the biomass of the photosensitive part of the rod cells. If the amount of DHA intake is insufficient, it can lead to a decrease in the content of DHA in the total fatty acid in the retinal cell tissue and affect vision. Some animal experiments have shown that insufficient unsaturated fatty acids in the food will cause the vision of these mammals to decline.

4. Anti-inflammatory

DHA has a certain effect on some chronic inflammations. These chronic inflammation signs include chronic prostatitis, rheumatoid arthritis and asthmatic bronchitis. The anti-inflammatory mechanism of DHA lies in: the chronic reaction substance SRSA is three specific leukotrienes, which are active substances in allergic reactions, and regulate bronchoconstriction and vascular permeability in allergic reactions. DHA can promote the biological formation of leukotriene LTB5 with anti-inflammatory effects. The use of omega-PUFA to prevent and treat certain inflammatory diseases such as rheumatoid arthritis and asthma has achieved good results.

5. Anti-cancer

DHA has a good immune regulation effect. Studies have shown that DHA can promote the proliferation of T lymphocytes and enhance the transcription of cytokines TNF-2, IL-1β and IL-6, thereby increasing the expression of cytokines, promoting the function of the immune system, and ultimately improving the immune system’s response to tumor cells. Lethality. In addition, DHA contains multiple double bonds in its structure and is a natural substrate for lipid peroxidation. The reactive oxygen species produced by lipid peroxidation can increase the sensitivity of tumor cells to therapeutic drugs, and the free radicals and lipid peroxides produced can inhibit the expression of tumor cells, shorten the telomeres of chromosomes, and promote tumor cell apoptosis.

6. Anti-allergy

DHA can hinder the biosynthesis of LTs, thereby inhibiting the production of platelet activating factor, thus being able to resist allergies. Therefore, DHA has achieved good results in the treatment and prevention of bronchial asthma, pollen allergy and allergic dermatitis.

7. DHA's other functions

Studies have reported that the lack of DHA can cause distraction and hyperactivity in children. In addition, a Japanese study showed that young students who consume fish oil rich in omega-3PUFAs are less likely to show provocative behavior during exam stress. Many studies believe that DHA can improve people's mood, and low levels of DHA in the body may be related to depression. Researchers from the National Agency for Alcohol Abuse and Alcohol Addiction in the United States conducted a study on the content of omega-3PUFAs in the blood of suicide patients. The results showed that among 50 suicide patients, the higher the content of omega-3PUFAs, the lower the suicidal desire. Ask the patient to supplement the appropriate amount of fish oil, and the patient's suicidal thoughts will also be eliminated. Another study believes that fish oil omega-3PUFAs can affect brain chemicals, so moderate fish oil supplementation can help alleviate negative emotions such as depression, suicide, and violent attacks. These findings indicate that omega-3PUFAs such as DHA may have a positive effect on alleviating abnormal psychological and behavioral diseases.

Reference

[1]Jia Junqian. Fermentation of Schizochytrium to produce docosahexaenoic acid[D]. Zhejiang University of Technology, 2015.

[2] Zhang Qiong. Research on Docosahexaenoic Acid (DHA) Fermentation Process[D]. Shanghai Normal University, 2014.

[3]Ma Fanti. Research on the fermentation process of algal oil docosahexaenoic acid[D]. Wuhan University of Technology, 2017.

[4]Xu Shixiong. Study on the selection and fermentation process of docosahexaenoic acid high-yielding strains[D]. Jiangnan University, 2013.

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