Docosahexaenoic acid
Encyclopedia
Docosahexaenoic acid is an omega-3 fatty acid
that is a primary structural component of the human brain and retina. In chemical structure, DHA is a carboxylic acid
with a 22-carbon chain and six cis double bond
s; the first double bond is located at the third carbon from the omega end. Its trivial name
is cervonic acid, its systematic name
is all-cis-docosa-4,7,10,13,16,19-hexa-enoic acid, and its shorthand name is 22:6(n-3) in the nomenclature of fatty acids.
Cold-water oceanic fish oil
s are rich in DHA. Most of the DHA in fish and complex organisms with access to cold-water oceanic foods originates in photosynthetic and heterotrophic microalgae, and becomes increasingly concentrated in organisms, as they move up the food chain. DHA is also commercially manufactured from microalgae; Crypthecodinium cohnii and another of the genus Schizochytrium. DHA manufactured using microalgae is vegetarian
. Some animals with access to seafood
make very little DHA through metabolism, but obtain it in the diet. However, in strict herbivores, and carnivores that do not eat seafood, DHA is manufactured internally from α-linolenic acid
, a shorter omega-3 fatty acid manufactured by plants (and also occurring in animal products as obtained from plants). Although α-linolenic acid (ALA) does convert to DHA in humans, the process is inefficient and very limited even in healthy individuals. DHA is a major fatty acid in sperm and brain phospholipid
s and in the retina. Dietary DHA may reduce the risk of heart disease
by reducing the level of blood
triglyceride
s in humans. Below-normal levels of DHA have been associated with Alzheimer's disease
.
s (PUFAs) in the brain and 60% of the PUFAs in the retina. Fifty percent of the weight of a neuron
's plasma membrane is composed of DHA.
DHA modulates the carrier-mediated transport of choline, glycine, and taurine, the function of delayed rectifier potassium channel
s, and the response of rhodopsin
contained in the synaptic vesicle
s, among many other functions.
DHA deficiency is associated with cognitive decline. Phosphatidylserine
(PS) controls apoptosis
, and low DHA levels lower neural cell PS and increase neural cell death.
DHA are reduced in the brain tissue of severely depressed patients.
(EPA, 20:5, ω-3) via docosapentaenoic acid
(DPA, 22:5 ω-3) as an intermediate. This synthesis had been thought to occur through an elongation step followed by the action of Δ4-desaturase
. It is now considered more likely that DHA is biosynthesized via a C24 intermediate followed by beta oxidation
in peroxisome
s. Thus, EPA is twice elongated, yielding 24:5 ω-3, then desaturated to 24:6 ω-3, then shortened to DHA (22:6 ω-3) via beta oxidation
. This pathway is known as Sprecher's shunt.
(NIH) intervention study to evaluate DHA in Alzheimer's disease.
Researchers from the National Institute on Aging-supported Alzheimer's Disease Cooperative Study conducted a double-blind, randomized, placebo-controlled clinical trial comparing DHA and placebo over 18 months in 402 people (average age=76) diagnosed with mild to moderate Alzheimer's at 51 sites. According to this study, treatment with DHA increased blood levels of DHA, and appeared to increase brain DHA levels, based on a measured increase of DHA in study participants' cerebrospinal fluid
.
However, DHA treatment did not slow the rate of change on tests of mental function, global dementia severity status, activities of daily living, or behavioral symptoms in the study population as a whole. Treatment effects did not differ between the mild and moderate Alzheimer's patients, leading study authors to conclude that the results do not support the routine use of DHA for patients with Alzheimer's.
Animal studies in the TG3 transgenic mouse model of Alzheimer's disease had linked dietary DHA to decreases in amyloid plaques and tau. Animal studies also showed, when DHA was combined with arachidonic acid
(also present in fish oil), plaque formation was greater with the arachidonic acid compared to DHA alone.
DHA deficiency likely plays a role in decline of mental function in healthy adults, which is indicated in a study from 2010 conducted at 19 U.S. clinical sites on 485 subjects aged 55 and older who met criteria for age-associated memory impairment. The study found algal DHA taken for six months decreased heart rate and improved memory and learning in healthy, older adults with mild memory complaints. These findings indicate the importance of early DHA intervention and provided a statistically significant benefit to cognitive function in individuals over 50 years of age.
Higher DHA levels in middle-aged adults is related to better performance on tests of nonverbal reasoning and mental flexibility, working memory, and vocabulary.
Such preliminary findings point to the need for further research, and are not proof DHA does or does not provide any benefit for intended treatment, cure, or mitigation of cancer. However, in 2008, DHA was shown to increase the efficacy of chemotherapy in prostate cancer cells, and in 2009, a chemoprotective effect in a mouse model
was reported. One large clinical trial, the "Prostate Cancer Prevention Trial", found that DHA was correlated with an increase in high-grade prostate cancer.
range from 0.07% to greater than 1.0% of total fatty acids, with a mean of about 0.34%. DHA levels in breast milk are higher if a mother's diet is high in fish. The Food and Drug Administration has noted specific concerns for women who are pregnant or might become pregnant, nursing mothers, and young children regarding mercury levels in fish and shellfish.
DHA has recently gained attention as a supplement for pregnant women, noting studies of improved attention and visual acuity. Given the recently gained attention, the majority of pregnant women in the U.S. fail to get the recommended amount of DHA in their diets. One recent study indicated low levels of plasma and erythrocyte DHA were associated with poor retinal development, low visual acuity, and poor cognitive development. In that same study, alpha-linolenic acid was shown as a source of fetal DHA, but preformed DHA was more readily accredited. A working group from the International Society for the Study of Fatty Acids and Lipids recommended 300 mg/day of DHA for pregnant and lactating women, whereas the average consumption was between 45 mg and 115 mg per day of the women in the study. The March of Dimes
recommends pregnant women consume at least 200 mg DHA per day.
Other requirements are available from other sources.
Docosahexaenoic acid single-cell oil (DHASCO) has been an ingredient in several brands of premium infant formula
sold in North America
since 2001 after Mead Johnson
, the first infant formula manufacturer to add DHASCO and arachidonic acid single-cell organism oil to its Enfamil Lipil product, received a "Generally Regarded As Safe" status by the Food and Drug Administration
and Health Canada.
DHASCO does not make infant formulas more like human milk than "conventional" formula containing alpha-linolenic acid
and linoleic acid
, which are precursors to DHA. Formula sold in North America uses lipids from microorganisms grown in bioreactor
s as sources of DHA. No scientific review studies show DHA additives benefit brain development of term infants, as formula makers claim in their advertisements, which has led some public interest groups to file complaints with the Federal Trade Commission
of the United States, alleging false and misleading advertising.
A study found that preterm infants fed baby formulas fortified with DHASCO provided better developmental outcomes than formulas not containing the supplement.
A study sponsored by March of Dimes and National Institutes of Health suggests that pregnant moms who take DHA supplements during pregnancy give their babies some degree of added protection against getting common cold
s. The babies whose mothers had taken DHA supplements seemed to get over cold symptoms faster when they did get sick.
in mothers or improve cognitive and language development in their offspring during early childhood.
Additional studies confirmed DHA benefits for other nervous system functions, cardiovascular health, and potentially other organs. In one study, men who took DHA supplements for 6–12 weeks decreased the concentrations of several inflammatory markers in their blood by approximately 20%. It has been shown that heart disease patients with higher intakes of DHA and EPA survived longer. A new study found that higher intake of DHA was associated with slower rates of telomere shortening, which is a basic DNA-level marker of aging. Preliminary studies showed that a high intake of DHA was associated with reduced risk for developing Alzheimer's disease, consistent with DHA being the most abundant omega-3 fatty acid in the brain. It is now considered so important to brain and eye development that DHA is included in most infant formulas. Lastly, in preliminary research, it was found that a diet rich in DHA might protect stroke victims from brain damage and disability and aid in a speedier recovery.
).
DHA is believed to be helpful to people with a history of heart disease
, for premature infants, and to support healthy brain development especially in young children along with supporting retinal development. Some manufactured DHA is a vegetarian product extracted from algae, and it competes on the market with fish oil that contains DHA and other omega-3's such as EPA
. Both fish oil and DHA are odorless and tasteless after processing as a food additive .
has been shown to increase EPA
, but not DHA. However, supplemental preformed DHA, available in algae-derived oils or capsules, has been shown to increase DHA levels. While there is little evidence of adverse health or cognitive effects due to DHA deficiency in adult vegetarians or vegans, fetal and breast milk levels remain a concern.
and IL-1β, associated with neurodegenerative and autoimmune diseases. They note the brain normally contains DHA, but not EPA, though both DHA and EPA plasma concentrations increased significantly for participants.
has been suggested as being helpful in the development of a large brain, though other researchers claim a terrestrial diet could also have provided the necessary DHA.
Omega-3 fatty acid
N−3 fatty acids are essential unsaturated fatty acids with a double bond starting after the third carbon atom from the end of the carbon chain....
that is a primary structural component of the human brain and retina. In chemical structure, DHA is a carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
with a 22-carbon chain and six cis double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...
s; the first double bond is located at the third carbon from the omega end. Its trivial name
Trivial name
In chemistry, a trivial name is a common name or vernacular name; it is a non-systematic name or non-scientific name. That is, the name is not recognised according to the rules of any formal system of nomenclature...
is cervonic acid, its systematic name
Systematic name
A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection...
is all-cis-docosa-4,7,10,13,16,19-hexa-enoic acid, and its shorthand name is 22:6(n-3) in the nomenclature of fatty acids.
Cold-water oceanic fish oil
Fish oil
Fish oil is oil derived from the tissues of oily fish. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid , and docosahexaenoic acid , precursors of certain eicosanoids that are known to reduce inflammation throughout the body, and are thought to have many health benefits.Fish do not...
s are rich in DHA. Most of the DHA in fish and complex organisms with access to cold-water oceanic foods originates in photosynthetic and heterotrophic microalgae, and becomes increasingly concentrated in organisms, as they move up the food chain. DHA is also commercially manufactured from microalgae; Crypthecodinium cohnii and another of the genus Schizochytrium. DHA manufactured using microalgae is vegetarian
Vegetarianism
Vegetarianism encompasses the practice of following plant-based diets , with or without the inclusion of dairy products or eggs, and with the exclusion of meat...
. Some animals with access to seafood
Seafood
Seafood is any form of marine life regarded as food by humans. Seafoods include fish, molluscs , crustaceans , echinoderms . Edible sea plants, such as some seaweeds and microalgae, are also seafood, and are widely eaten around the world, especially in Asia...
make very little DHA through metabolism, but obtain it in the diet. However, in strict herbivores, and carnivores that do not eat seafood, DHA is manufactured internally from α-linolenic acid
Alpha-linolenic acid
α-Linolenic acid is an organic compound found in many common vegetable oils. In terms of its structure, it is named all-cis-9,12,15-octadecatrienoic acid. In physiological literature, it is given the name 18:3 ....
, a shorter omega-3 fatty acid manufactured by plants (and also occurring in animal products as obtained from plants). Although α-linolenic acid (ALA) does convert to DHA in humans, the process is inefficient and very limited even in healthy individuals. DHA is a major fatty acid in sperm and brain phospholipid
Phospholipid
Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline; one exception to this rule is sphingomyelin, which is derived from...
s and in the retina. Dietary DHA may reduce the risk of heart disease
Heart disease
Heart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...
by reducing the level of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
triglyceride
Triglyceride
A triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....
s in humans. Below-normal levels of DHA have been associated with Alzheimer's disease
Alzheimer's disease
Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
.
Central nervous system constituent
DHA is the most abundant omega-3 fatty acid in the brain and retina. DHA comprises 40% of the polyunsaturated fatty acidPolyunsaturated fatty acid
Polyunsaturated fatty acids are fatty acids that contain more than one double bond in their backbone. This class includes many important compounds, such as essential fatty acids and those that give drying oils their characteristic property....
s (PUFAs) in the brain and 60% of the PUFAs in the retina. Fifty percent of the weight of a neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
's plasma membrane is composed of DHA.
DHA modulates the carrier-mediated transport of choline, glycine, and taurine, the function of delayed rectifier potassium channel
Potassium channel
In the field of cell biology, potassium channels are the most widely distributed type of ion channel and are found in virtually all living organisms. They form potassium-selective pores that span cell membranes...
s, and the response of rhodopsin
Rhodopsin
Rhodopsin, also known as visual purple, is a biological pigment of the retina that is responsible for both the formation of the photoreceptor cells and the first events in the perception of light. Rhodopsins belong to the G-protein coupled receptor family and are extremely sensitive to light,...
contained in the synaptic vesicle
Synaptic vesicle
In a neuron, synaptic vesicles store various neurotransmitters that are released at the synapse. The release is regulated by a voltage-dependent calcium channel. Vesicles are essential for propagating nerve impulses between neurons and are constantly recreated by the cell...
s, among many other functions.
DHA deficiency is associated with cognitive decline. Phosphatidylserine
Phosphatidylserine
Phosphatidylserine is a phospholipid component, usually kept on the inner-leaflet of cell membranes by an enzyme called flippase...
(PS) controls apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
, and low DHA levels lower neural cell PS and increase neural cell death.
DHA are reduced in the brain tissue of severely depressed patients.
Metabolic synthesis
In humans, DHA is either obtained from the diet or synthesized from eicosapentaenoic acidEicosapentaenoic acid
Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...
(EPA, 20:5, ω-3) via docosapentaenoic acid
Docosapentaenoic acid
Docosapentaenoic acid designates any straight chain 22:5 fatty acid.Two isomers are of particular interest* all-cis-7,10,13,16,19-docosapentaenoic acid is an ω-3 fatty acid with the trivial name clupanodonic acid, commonly called DPA. It is an intermediary between eicosapentaenoic acid and...
(DPA, 22:5 ω-3) as an intermediate. This synthesis had been thought to occur through an elongation step followed by the action of Δ4-desaturase
Desaturase
A fatty acid desaturase is an enzyme that removes two hydrogen atoms from a fatty acid, creating a carbon/carbon double bond. These desaturases are classified as...
. It is now considered more likely that DHA is biosynthesized via a C24 intermediate followed by beta oxidation
Beta oxidation
Beta oxidation is the process by which fatty acids, in the form of Acyl-CoA molecules, are broken down in mitochondria and/or in peroxisomes to generate Acetyl-CoA, the entry molecule for the Citric Acid cycle....
in peroxisome
Peroxisome
Peroxisomes are organelles found in virtually all eukaryotic cells. They are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, D-amino acids, polyamines, and biosynthesis of plasmalogens, etherphospholipids critical for the normal function of mammalian brains...
s. Thus, EPA is twice elongated, yielding 24:5 ω-3, then desaturated to 24:6 ω-3, then shortened to DHA (22:6 ω-3) via beta oxidation
Beta oxidation
Beta oxidation is the process by which fatty acids, in the form of Acyl-CoA molecules, are broken down in mitochondria and/or in peroxisomes to generate Acetyl-CoA, the entry molecule for the Citric Acid cycle....
. This pathway is known as Sprecher's shunt.
Attention Deficit Hyperactivity Disorder (ADHD)
Research on DHA supplementation and Attention Deficit Hyperactivity Disorder (ADHD) have shown mixed results. One study of pure DHA supplementation on children with ADHD found no behavioral improvements, while another study found fish oil containing both EPA and DHA did improve behavior.Alzheimer's disease and decline of mental health
Preliminary studies indicated that DHA can slow the progression of Alzhiemer's disease in mice, sparking interest in additional research. However, the first large-scale human trials showed that DHA did not slow decline of mental function in elderly people with mild to moderate Alzheimer's disease. These trials were part of a large US National Institutes of HealthNational Institutes of Health
The National Institutes of Health are an agency of the United States Department of Health and Human Services and are the primary agency of the United States government responsible for biomedical and health-related research. Its science and engineering counterpart is the National Science Foundation...
(NIH) intervention study to evaluate DHA in Alzheimer's disease.
Researchers from the National Institute on Aging-supported Alzheimer's Disease Cooperative Study conducted a double-blind, randomized, placebo-controlled clinical trial comparing DHA and placebo over 18 months in 402 people (average age=76) diagnosed with mild to moderate Alzheimer's at 51 sites. According to this study, treatment with DHA increased blood levels of DHA, and appeared to increase brain DHA levels, based on a measured increase of DHA in study participants' cerebrospinal fluid
Cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...
.
However, DHA treatment did not slow the rate of change on tests of mental function, global dementia severity status, activities of daily living, or behavioral symptoms in the study population as a whole. Treatment effects did not differ between the mild and moderate Alzheimer's patients, leading study authors to conclude that the results do not support the routine use of DHA for patients with Alzheimer's.
Animal studies in the TG3 transgenic mouse model of Alzheimer's disease had linked dietary DHA to decreases in amyloid plaques and tau. Animal studies also showed, when DHA was combined with arachidonic acid
Arachidonic acid
Arachidonic acid is a polyunsaturated omega-6 fatty acid 20:4.It is the counterpart to the saturated arachidic acid found in peanut oil, Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6).It is the counterpart to the saturated arachidic acid found in peanut oil,...
(also present in fish oil), plaque formation was greater with the arachidonic acid compared to DHA alone.
DHA deficiency likely plays a role in decline of mental function in healthy adults, which is indicated in a study from 2010 conducted at 19 U.S. clinical sites on 485 subjects aged 55 and older who met criteria for age-associated memory impairment. The study found algal DHA taken for six months decreased heart rate and improved memory and learning in healthy, older adults with mild memory complaints. These findings indicate the importance of early DHA intervention and provided a statistically significant benefit to cognitive function in individuals over 50 years of age.
Higher DHA levels in middle-aged adults is related to better performance on tests of nonverbal reasoning and mental flexibility, working memory, and vocabulary.
Cancer
DHA was found to inhibit growth of human colon carcinoma cells, more than other omega-3 PUFAs. The cytotoxic effect of DHA was not caused by increased lipid peroxidation or any other oxidative damage, but rather a decrease in cell growth regulators. However, different cancer lines handle PUFAs differently and display different sensitivities toward them.Such preliminary findings point to the need for further research, and are not proof DHA does or does not provide any benefit for intended treatment, cure, or mitigation of cancer. However, in 2008, DHA was shown to increase the efficacy of chemotherapy in prostate cancer cells, and in 2009, a chemoprotective effect in a mouse model
Animal model
An animal model is a living, non-human animal used during the research and investigation of human disease, for the purpose of better understanding the disease without the added risk of causing harm to an actual human being during the process...
was reported. One large clinical trial, the "Prostate Cancer Prevention Trial", found that DHA was correlated with an increase in high-grade prostate cancer.
Pregnancy and lactation
DHA concentrations in breast milkBreast milk
Breast milk, more specifically human milk, is the milk produced by the breasts of a human female for her infant offspring...
range from 0.07% to greater than 1.0% of total fatty acids, with a mean of about 0.34%. DHA levels in breast milk are higher if a mother's diet is high in fish. The Food and Drug Administration has noted specific concerns for women who are pregnant or might become pregnant, nursing mothers, and young children regarding mercury levels in fish and shellfish.
DHA has recently gained attention as a supplement for pregnant women, noting studies of improved attention and visual acuity. Given the recently gained attention, the majority of pregnant women in the U.S. fail to get the recommended amount of DHA in their diets. One recent study indicated low levels of plasma and erythrocyte DHA were associated with poor retinal development, low visual acuity, and poor cognitive development. In that same study, alpha-linolenic acid was shown as a source of fetal DHA, but preformed DHA was more readily accredited. A working group from the International Society for the Study of Fatty Acids and Lipids recommended 300 mg/day of DHA for pregnant and lactating women, whereas the average consumption was between 45 mg and 115 mg per day of the women in the study. The March of Dimes
March of Dimes
The March of Dimes Foundation is a United States nonprofit organization that works to improve the health of mothers and babies.-Organization:...
recommends pregnant women consume at least 200 mg DHA per day.
Other requirements are available from other sources.
Docosahexaenoic acid single-cell oil (DHASCO) has been an ingredient in several brands of premium infant formula
Infant formula
Infant formula is a manufactured food designed and marketed for feeding to babies and infants under 12 months of age, usually prepared for bottle-feeding or cup-feeding from powder or liquid . The U.S...
sold in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
since 2001 after Mead Johnson
Mead Johnson
Mead Johnson & Company is a company which was majority owned by Bristol-Myers Squibb after an acquisition in 1967, but was spun off in 2009 as an independent firm. Mead Johnson is a major manufacturer of infant formula both domestically and globally with its flagship product Enfamil...
, the first infant formula manufacturer to add DHASCO and arachidonic acid single-cell organism oil to its Enfamil Lipil product, received a "Generally Regarded As Safe" status by the Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
and Health Canada.
DHASCO does not make infant formulas more like human milk than "conventional" formula containing alpha-linolenic acid
Alpha-linolenic acid
α-Linolenic acid is an organic compound found in many common vegetable oils. In terms of its structure, it is named all-cis-9,12,15-octadecatrienoic acid. In physiological literature, it is given the name 18:3 ....
and linoleic acid
Linoleic acid
Linoleic acid is an unsaturated n-6 fatty acid. It is a colorless liquid at room temperature. In physiological literature, it has a lipid number of 18:2...
, which are precursors to DHA. Formula sold in North America uses lipids from microorganisms grown in bioreactor
Bioreactor
A bioreactor may refer to any manufactured or engineered device or system that supports a biologically active environment. In one case, a bioreactor is a vessel in which a chemical process is carried out which involves organisms or biochemically active substances derived from such organisms. This...
s as sources of DHA. No scientific review studies show DHA additives benefit brain development of term infants, as formula makers claim in their advertisements, which has led some public interest groups to file complaints with the Federal Trade Commission
Federal Trade Commission
The Federal Trade Commission is an independent agency of the United States government, established in 1914 by the Federal Trade Commission Act...
of the United States, alleging false and misleading advertising.
A study found that preterm infants fed baby formulas fortified with DHASCO provided better developmental outcomes than formulas not containing the supplement.
A study sponsored by March of Dimes and National Institutes of Health suggests that pregnant moms who take DHA supplements during pregnancy give their babies some degree of added protection against getting common cold
Common cold
The common cold is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever...
s. The babies whose mothers had taken DHA supplements seemed to get over cold symptoms faster when they did get sick.
Current Research
Although most studies demonstrate positive effects of dietary DHA on human health, contrary results exist. For example, one study found that the use of DHA-rich fish oil capsules did not reduce postpartum depressionPostpartum depression
Postpartum depression , also called postnatal depression, is a form of clinical depression which can affect women, and less frequently men, typically after childbirth. Studies report prevalence rates among women from 5% to 25%, but methodological differences among the studies make the actual...
in mothers or improve cognitive and language development in their offspring during early childhood.
Additional studies confirmed DHA benefits for other nervous system functions, cardiovascular health, and potentially other organs. In one study, men who took DHA supplements for 6–12 weeks decreased the concentrations of several inflammatory markers in their blood by approximately 20%. It has been shown that heart disease patients with higher intakes of DHA and EPA survived longer. A new study found that higher intake of DHA was associated with slower rates of telomere shortening, which is a basic DNA-level marker of aging. Preliminary studies showed that a high intake of DHA was associated with reduced risk for developing Alzheimer's disease, consistent with DHA being the most abundant omega-3 fatty acid in the brain. It is now considered so important to brain and eye development that DHA is included in most infant formulas. Lastly, in preliminary research, it was found that a diet rich in DHA might protect stroke victims from brain damage and disability and aid in a speedier recovery.
The Discovery of Algae-based DHA
In the early 1980s, NASA sponsored scientific research in search of a plant-based food source that could generate oxygen and nutrition on long-duration space flights. The researchers discovered that certain species of marine algae produced rich nutrients. This research led to the development of an algae-based, vegetable-like oil that contains two essential polyunsaturated fatty acids: DHA and ARA (Arachidonic acidArachidonic acid
Arachidonic acid is a polyunsaturated omega-6 fatty acid 20:4.It is the counterpart to the saturated arachidic acid found in peanut oil, Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6).It is the counterpart to the saturated arachidic acid found in peanut oil,...
).
Use as a food additive
DHA is widely used as a food supplement. It was first used primarily in infant formulas. In 2004, the US Food and Drug Administration endorsed qualified health claims for DHA, and by 2007 DHA-fortified dairy items (milk, yogurt, cooking oil) started to appear in grocery stores.DHA is believed to be helpful to people with a history of heart disease
Heart disease
Heart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...
, for premature infants, and to support healthy brain development especially in young children along with supporting retinal development. Some manufactured DHA is a vegetarian product extracted from algae, and it competes on the market with fish oil that contains DHA and other omega-3's such as EPA
Eicosapentaenoic acid
Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...
. Both fish oil and DHA are odorless and tasteless after processing as a food additive .
Studies of vegetarians and vegans
Vegetarian diets typically contain limited amounts of DHA, and vegan diets typically contain no DHA. Vegetarians and vegans have substantially lower levels of DHA in their bodies, and short-term supplemental ALAAlpha-linolenic acid
α-Linolenic acid is an organic compound found in many common vegetable oils. In terms of its structure, it is named all-cis-9,12,15-octadecatrienoic acid. In physiological literature, it is given the name 18:3 ....
has been shown to increase EPA
Eicosapentaenoic acid
Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...
, but not DHA. However, supplemental preformed DHA, available in algae-derived oils or capsules, has been shown to increase DHA levels. While there is little evidence of adverse health or cognitive effects due to DHA deficiency in adult vegetarians or vegans, fetal and breast milk levels remain a concern.
DHA and EPA in fish oils
Fish oil is widely sold in gelatin capsules containing a mixture of omega-3 fatty acids including EPA and smaller quantities of DHA. One study found fish oil higher in DHA than EPA lowered inflammatory cytokines, such as IL-6Interleukin 6
Interleukin-6 is a protein that in humans is encoded by the IL6 gene.IL-6 is an interleukin that acts as both a pro-inflammatory and anti-inflammatory cytokine. It is secreted by T cells and macrophages to stimulate immune response, e.g. during infection and after trauma, especially burns or other...
and IL-1β, associated with neurodegenerative and autoimmune diseases. They note the brain normally contains DHA, but not EPA, though both DHA and EPA plasma concentrations increased significantly for participants.
Hypothesized role in evolution
An abundance of DHA in seafoodSeafood
Seafood is any form of marine life regarded as food by humans. Seafoods include fish, molluscs , crustaceans , echinoderms . Edible sea plants, such as some seaweeds and microalgae, are also seafood, and are widely eaten around the world, especially in Asia...
has been suggested as being helpful in the development of a large brain, though other researchers claim a terrestrial diet could also have provided the necessary DHA.
See also
- DHA-ClozapinDHA-clozapineDHA-clozapine is an atypical antipsychotic that has been developed by Protarga. The drug has been created by the association of the fatty acid docosahexaenoic acid with clozapine...
- List of omega-3 fatty acids
- Polyunsaturated fatty acidPolyunsaturated fatty acidPolyunsaturated fatty acids are fatty acids that contain more than one double bond in their backbone. This class includes many important compounds, such as essential fatty acids and those that give drying oils their characteristic property....
s
External links
- DHA / EPA Omega-3 Institute – Recent studies, overviews, and objective science.
- Docosahexaenoic acid (DHA) – University of Maryland Medical Center (UMMC)
- Docosahexaenoic acid - DHA ChemSub Online