DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits

Abstract

With the increasing interest in health and nutrition for longevity of life and more performance ability, the idea of health foods and nutrients has attracted more research and studies. Omega-3 fatty acid docosahexaenoic acid (DHA) is a nutrient molecule with various diverse roles and health benefits in the human body. Though DHA originally comes from microalgae and sea plants, the main source of DHA is fish, shellfish, and fish oils. DHA is a key nutrient with a structural and functional role in the cell membrane and cell organelles, and abundant in brain and eye. It is good for the heart, and protective against heart diseases. It is rather a very ancient molecule with more modern concepts. Really, DHA has been proven to be a key nutrient that is required in the processes of physical and mental development and health, and prevention of diseases throughout the life span. Driven by the values of physical and mental health, the demand for DHA in the international market is expected to grow. This review is an attempt to update the research findings about DHA and its health benefits in an easy and lucid way.

1. Introduction

Everybody on this planet would like to lead a beautiful, happy, and meaningful life. However, we are what we eat. A sound body and a sound mind come from what we are made up of. So, a perfect knowledge of what we intake daily in our diet and especially in the stages of pregnancy, infancy, and childhood is very important. Interest in omega-3 fatty acids has increased in recent years because of their various roles in health promotion and disease risk reduction [1]. With increasing interest in health consciousness and our well-being, the essential omega-3 fatty acids have been the most studied biomolecules during the last few decades. These omega-3 fatty acids have strong implications in medicine as they have been linked to various health conditions, such as inflammation, cancer, heart diseases, and neurological disorders. Docosahexaenoic acid DHA is the key component of all cell membranes of the body and the most important fatty acid, which is concentrated in the brain and central nervous system and is referred to as “brain food.” On account of its diverse amazing roles and health benefit, it has become the star nutrient molecule nowadays [2]. Bradburry call the DHA molecule an ancient molecule for the modern human brain [3]. An optimum level of the omega-3 fatty acid DHA in the body is required for efficient body functions. Omega-3 fatty acids have been linked to healthy aging throughout life [4]. As these PUFA are essential, normal infant/neonatal brain, intellectual growth, and development cannot be accomplished if they are deficient during pregnancy and lactation. Sustaining normal adult brain function also requires PUFA.

Studies suggest that the evolution of large human brain occurred depending on the rich source of preformed long-chain PUFA at the interface of land and water. The human diet has changed to a large extent during the last 100 years. One of the striking changes is the enormous increase in dietary fat. In terms of quality, we have increased our intakes of saturated fatty acids (SFA), alpha-linoleic acid (LA) and trans fatty acids, concomitant with reduced intakes of (n-3) fatty acids. The latter comprises reduced intake of 3-linolenic acid (ALA) rich foods, and less consumption of long-chain PUFA of the (n-3) series [LC(n-3)P], that is, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids notably from fish [1]. These dietary and other environmental changes are deemed to be among the major causes of the rapid expansion of diet-related chronic disease [2], including cardiovascular disease (CVD) in the past century [5].

The question is: Are we getting enough of the DHA in our daily diet? DHA is found mainly in seafood, such as fish, shellfish, and fish oils. It is also found in some types of algae [6]. So, the objective of the chapter is to review and discuss the diverse amazing health benefits and roles and to make sure if we are getting enough DHA in our diet.

2. Defining DHA: one biomolecule diverse functions

DHA (docosahexaenoic acid) is an important omega -3 polyunsaturated fatty acid (PUFA) consisting of a long chain of 22 carbon atoms and 6 double bonds. DHA is mainly found in fish and fish oil with EPA. It is remarkable that one simple molecule has been reported to affect so many apparently unrelated biological processes.

DHA molecule is an integral part of all cell membranes and critical to membrane fluidity [7]. Aptly referring to “DHA as brain food,” docosahexaenoic acid (DHA) is the predominant omega-3 (n-3) polyunsaturated fatty (PUFA) found in the brain and can do neurological function through signal transduction, pathway, neurotransmission, neurogenesis, membrane receptor function, synaptic plasticity, healthy inflammation balance, membrane organization, and membrane integrity [8].

Important functions of DHA include antioxidant activity, memory formation, neurogenesis, acting as a signaling molecule. Researchers conclude that it is fairly astonishing how DHA, a single molecule, plays so many roles. The present-day diet typically lacks appreciable amounts of DHA. Therefore, in modern population maintaining optimal levels of DHA in the brain throughout the lifespan likely requires obtaining preformed DHA via dietary supplemental sources. Most omega-3 supplements contain both DHA and EPA but there are many high-quality DHA supplements also available when more of this precious nutrient is desirable.

3. Sources of DHA

Important omega-3 fatty acids are DHA, EPA, and ALA. Polyunsaturated fatty acids, particularly n-3 PUFA, DHA, and EPA are the prominent compounds found in fish [9]. ALA is present in different plant seeds and grains that convert a small amount into EPA and DHA after human consumption. Flaxseed oil is a major plant source of ALA [10]. In the human diet, the main contributors of DHA and EPA are marine ecosystems (fish, shellfish, and other sea foods) [11]. Fish liver contains a large number of omega-3 fatty acids that have been proven by different studies to lower blood triglycerides and cholesterol levels. Actually, fatty predatory fish like sharks have a lot of omega-3 fatty acids in their tissues that possess a lot of health benefits, particularly in terms of reducing inflammation, improving mental health, and serving as an antioxidant [11]. Fatty fishes, such as Salmo salar (salmon Gadus morhua (cod), Thunnus thynnus (tuna),) Tenualosa ilisha, Sardinella longiceps, Schizothorax richardsonii, and Neolisochilus hexaganolepis, have numerous roles as main sources of DHA and other polyunsaturated fatty acids [12]. Micro- and macroalgae are original sources of DHA [13]. Another study stated that egg yolk contains ALA (0.8%), DHA (0.7%), and EPA (0.1%). Additionally, egg yolk, lean red meat, chicken, and human milk are also good sources of ALA [14].

4. Reason for intake of DHA in our diet

Human body cannot synthesize enough amount of DHA from α-linolenic acid (ALA), under the actions of fatty acid elongases and desaturases, the bioconversion rate in the human body is extremely low, generally at 2–10%), and sometimes, it was reported even at a lower rate of 0.01%. Therefore, DHA-rich or fortified foods and DHA supplements are the two main exogenous sources to obtain additional DHA needed for the biological functions of human body [15].

Important roles of DHA are found in Figure 1.

1. Eyes, 2. Brain, 3. Heart, 4. Developing infants and children, 5. Bones, 6. Joints, 7. Skin, and 8. Spermatozoa (Figure 1).

Figure 1.

Picture showing important benefits of DHA.

Docosahexaenoic acid (DHA) is essential for the growth and functional development of the brain in infants. DHA is also needed for the maintenance of normal brain function in adults. The inclusion of plentiful DHA in the diet boosts learning ability, whereas deficiencies of DHA are associated with deficits in learning. DHA deficiencies are also associated with fetal alcohol syndrome, attention deficit hyperactivity disorder, cystic fibrosis, phenylketonuria, unipolar depression, aggressive hostility, and adrenoleukodystrophy [16]. Decreases in DHA in the brain are correlated with cognitive decline during aging and with the onset of sporadic Alzheimer’s disease.

Several researchers have shown that ω-3 PUFAs play a major role in altering blood lipid profiles and membrane lipid composition and affect eicosanoid biosynthesis, cell signaling cascades, and gene expression, thereby influencing health [17, 18]. In addition, the beneficial effect of ω-3 PUFAs in patients with myriad health conditions and diseases, such as cardiovascular disease (atrial fibrillation, atherosclerosis, thrombosis, inflammation, and sudden cardiac death, among others), diabetes, cancer, depression and various mental illnesses, age-related cognitive decline, periodontal disease, and rheumatoid arthritis, has been investigated [19, 20].

5. Brain development during pregnancy and early life

Controlling and shaping a child’s destiny should start from the stage of pregnancy. Nutrition in pregnancy, during lactation, childhood, and later stages has an important influence on overall development. DHA is a bioactive omega-3 polyunsaturated fatty acid that influences membrane structure and function, cell signaling and communication mechanisms, gene expression, and lipid mediator production. DHA is found in high concentrations in the human brain and eye, where it is linked to better development and function. Maintenance of DHA concentration is important throughout the life course, but pregnancy, lactation, and infancy are vulnerable periods, whereas insufficient DHA supply can impact mental and visual development and performance [21].

Docosahexaenoic acid, 22:6n-3 (DHA), is crucially necessary for the structure and development of the growing fetal brain in utero. DHA is the dominant n-3 long-chain polyunsaturated fatty acid in brain gray matter representing about 15% of all fatty acids in the human frontal cortex. DHA has roles in neurogenesis, neurotransmitter, synaptic plasticity and transmission, and signal transduction in the brain. Data from human and animal studies indicate that adequate levels of DHA in neural membranes are required for the maturation of cortical astrocyte, neurovascular coupling, and glucose uptake and metabolism. Besides, some metabolites of DHA are protective against oxidative tissue injury and stress in the brain. A low DHA level in the brain produces behavioral changes and is associated well with learning difficulties and dementia. In humans, the third trimester-placental supply of maternal DHA to the growing fetus is crucially important as the growing brain obligatorily needs DHA during this window period. Moreover, DHA takes part in the early placentation process, essential for placental development [22].

Docosahexaenoic acid has a rapid accumulation in the brain from week 30 of pregnancy to 2 years postpartum. About 67 mg of DHA is accrued by the fetus per day, thereby increasing its brain weight and making it important for the mother to have adequate DHA intake during this time. The DHA accretion during lactation is 70–80 mg/day, and this huge demand for DHA during lactation depletes maternal stores and may take months to recover even partially [14]. The increasing concentration of DHA takes place nearly 30-fold during the growth spurts of the brain, which corresponds to the beginning of the third trimester of pregnancy to 18 months after birth [23]. During these early growth spurts, the brain is critically vulnerable to nutritional deficiencies. Preterm infants much miss out on the chance of DHA accretion during the last trimester and thus would benefit from external supplementation [24]. Arachidonic acid begins accretion in the brain during the last trimester of pregnancy and continues to accumulate until 2 years of postnatal age. Accretion of about 95 mg/day of ARA takes place during the last 5 weeks of gestation; this is nearly twice the amount of DHA accrued during the same period. A larger amount of the ARA is accumulated in the adipose tissue and skeletal muscles, with relatively lesser amounts accumulated in the brain [25].

A supply of DHA is very important early in life, especially during the fetal and early infant periods when the eye and central nervous system are developing. During pregnancy, transfer of DHA including EPA is done through the placenta from mother to the fetus [26]. The level of omega-3 fatty acid in the fetus is correlated with the amount ingested by the mother, so it is essential that the mother has adequate nutrition [4]. The function of DHA in the brain is to support the transmission of messages through nerve cells and to protect the brain against the loss of scaffolding proteins and oxidative degradation of lipids, thus helping maintain the plasticity of the brain [27]. DHA also plays a functional role in gene expression, myelination, and growth and differentiation of neurons [28]. DHA is also a basic membrane component of the photoreceptor cells of the eye, and proper functioning of the photoreceptor cells is essential for vision [29, 30]. Arachidonic acid is an omega-6 (n-6) fatty acid that plays important roles in brain functioning, including neuronal firing, signal transmission, and long-term potentiation. Besides, ARA preserves hippocampal neuron membrane plasticity, protects the brain against oxidative stress, and aids in the synthesis of new proteins in brain tissues [31].

EPA and DHA supplementation during pregnancy has been found with multiple benefits for the infant. Numerous studies confirmed the benefit of omega-3 supplementation during pregnancy in terms of proper development of the brain and retina. Of the two most important long-chain omega-3 fatty acids, EPA and DHA, DHA is the more crucial for proper cell membrane function and is vital to the development of the fetal brain and retina [32].

6. DHA supplementation after birth

The need for adequate DHA intake for women does not stop after the birth of a healthy baby. DHA goes on rapidly to accumulate in the brains of infants and young children through at least the second year of life [33]. However, human infants can only synthesize DHA in very limited amount, making them dependent on dietary sources, such as breast milk, formula, or DHA supplements [34].

It has long been known that breastfed infants have higher IQs and more advanced cognition than bottle-fed babies [35, 36]. It is now clearly known that one reason for this difference may be that breast milk normally contains DHA. Like the placenta, the milk-producing apparatus in the human breast routinely pulls DHA and other brain-nourishing fatty acids from the mother’s blood in preference to other fats, delivering the highest possible amounts to the breastfed infant. Again, this result can come at the expense of the mother’s own DHA supplies if steady intake is not assured. The DHA content of the maternal diet is the most important factor determining how much DHA is found in breast milk. Some experts have raised concerns that the consumption of otherwise healthy low-fat diets by women of reproductive age could reduce the amount of DHA available to them during pregnancy and lactation [37]. Given the known low levels of DHA in most women’s diets, this observation strongly suggests that DHA supplementation in nursing mothers is critical to optimizing brain development in their infants. DHA supplementation by nursing mothers increases the DHA content in their milk and in infant red blood cells, which is associated with enhanced visual acuity at 4 months [38, 39] and early language development in breastfed infants [33]. High maternal DHA intake is also associated with improved long-term growth in breastfed children [40, 41, 42]. Longer duration of breastfeeding and higher ratios of DHA to arachidonic acid (a precursor to DHA) was associated with higher total IQ scores in these school-aged children. The DHA that gets stored in the brain during infancy is an essential building block for children’s cognitive, social, emotional, and behavioral development. Higher levels of DHA in infants are connected to stronger development of language, cognition, social, and motor skills as they move out of infancy and into young childhood [32].

7. DHA and inflammation

The role of omega-3 (EPA + DHA) in promoting the resolution of inflammation is an exciting development. Immunity, inflammation, and metabolic health are interrelated. Inflammation drives poor metabolic health. Inflammation leads to morbidity and mortality. Specific nutritional strategies can target inflammation to improve metabolic health. These same strategies target immunity—P.C. Calder.

Inflammation is a key component of normal host defense mechanisms initiating the immune response and later playing a role in tissue repair. Inappropriate, excessive, or uncontrolled inflammation contributes to human diseases and is believed to play a central role in many of the chronic diseases that characterize modern society [43, 44, 45].

Fatty acids can give influence on inflammation through a variety of mechanisms, including acting via cell surface and intracellular receptors/sensors that control inflammatory cell signaling and gene expression patterns. Some effects of fatty acids on inflammatory cells seem to be mediated by, or at least are associated with, changes in the fatty acid composition of cell membranes. Alterations in these compositions can modify membrane fluidity, lipid raft formation, cell signaling leading to altered gene expression, and the pattern of lipid and peptide mediator production [43, 45]. Cells within the inflammatory response are typically rich in the n-6 fatty acid arachidonic acid, but the contents of arachidonic acid and of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can be altered through oral administration of EPA and DHA. Eicosanoids produced from arachidonic acid have inflammatory roles [45, 46]. EPA also produces eicosanoids and these may have differing properties from those of arachidonic acid-derived eicosanoids. EPA and DHA produce resolvins that are anti-inflammatory and inflammation-resolving. Thus, fatty acid exposure and the fatty acid composition of human inflammatory cells have an impact on their function. As a result of their anti-inflammatory actions, marine n-3 fatty acids have healing roles in rheumatoid arthritis, although benefits in other inflammatory diseases and conditions have not been unequivocally demonstrated [45, 46]. The anti-inflammatory effects of marine n-3 fatty acids may contribute to their protective roles toward atherosclerosis, plaque rupture, and cardiovascular mortality. The role of resolvins and related compounds may be very important because the resolution of inflammation is important in shutting off the ongoing inflammatory process and in limiting tissue damage [44]. Human trials show the benefits of oral n-3 fatty acids in rheumatoid arthritis and in stabilizing advanced atherosclerotic plaques. Intravenous n-3 fatty acids may be useful in critically ill patients through reduced inflammation. The anti-inflammatory and inflammation-resolving actions of EPA, DHA, and their derivatives are of clinical relevance [47].

Evidence suggests that, in addition to the amount of fat, the types of fats consumed can have a differential impact on human health. Their results on the risk of cardiovascular disease have dominated the rationale for these recommendations for the past 50 years [48]. There is increasing recognition by leaders in the nutrition and health field that dietary fats can affect host inflammatory responses [15].

8. DHA and cardiovascular disease

CVD is the leading cause of mortality in the world. For example, the prevalence of CVD in China is still rising [49] and India has a much higher rate of 272 per 10,000 higher than that of the global average of 235 [50]. AHA 2022 reports that CVD is the leading cause of death in America [7]. Some researchers have shown that n-3 fatty acids play a role in the protection against cardiovascular heart disease [51], sudden coronary death [52, 53], and peripheral arterial disease [54]. In addition, n- 3 omega-3 fatty acids have multiple beneficial effects on reducing cardio-metabolic risk factors, including dyslipidemia [55], increased blood pressure [56], arterial compliance [55], inflammation [57, 58] and vascular reactivity [59]. A recent meta-analysis showed that there were 9% and 13% risk reductions in coronary heart disease (CHD) events and myocardial infarction, respectively, with 1 g/day DHA supplements, and the effects were dose-dependent [60].

Earlier studies were done on the benefits of n- 3 LCPUFA in preventing CVD using a combination of EPA and DHA. In recent years, the separate effects of EPA and DHA on the risk factors of CVD have been shown in order to have a better understanding of their mechanisms. Asztalos et al. [60] recruited 121 healthy, normolipidemic subjects, where subjects were randomly assigned into four treatment groups: two doses of EPA (1800 and 600 mg/day), one dose of DHA (600 mg/day), and olive oil without EPA and DHA (control). After 6 weeks of intervention, the DHA group showed a significant decrease in the postprandial TG concentration compared with the control group although the fasting TG remained unchanged. However, interestingly, the DHA group also displays a significant increase in the low-density lipoprotein cholesterol (LDL) level. Although the EPA groups did not show the same results, there was a significant decrease in the lipoprotein-associated phospholipase A2 concentration, which is an inflammatory marker, at the dose of 1800 mg EPA/day. It seems that both EPA and DHA can decrease the CVD risk factors, and DHA may be more effective in reducing the lipid risk factors than EPA [61].

9. Cancers

Cancer is one of the most frequently diagnosed diseases worldwide, cancer is one of the leading causes of death in the Western world, and omega-3 fatty acids have long been claimed to reduce the risk of certain cancers. Interestingly, studies indicate that people who take the most omega-3s have up to a 55% lower risk of colon cancer [62, 63]. Additionally, omega-3 consumption is linked to a reduced risk of prostate cancer in men and breast cancer in women. However, not all studies show the same results [64, 65, 66].

10. Vision and eye health

Age-related macular degeneration is a major cause of blindness worldwide. With aging populations in many countries, more than 20% might have the disorder. DHA, a type of omega-3, is a key structural component of the retina of your eye [67]. When enough DHA is not present in the body, vision problems may arise [68, 69]. Interestingly having enough omega-3 is linked to a reduced risk of macular degeneration, one of the world’s leading causes of permanent eye damage and blindness [69, 70].

11. Inflammatory bowel disease

The anti-inflammatory effects of omega-3 fats may assist in managing inflammatory bowel disease (IBD) and other gastrointestinal diseases causing inflammation, but the available evidence is weak [71, 72]. In one study, 4.2 g of fish oil daily for 8 months reduced the symptoms of active mild-to-moderate ulcerative colitis [73]. However, a review of three clinical trials and 138 ulcerative colitis patients found no significant benefits of fish oil supplementation. The authors suggested further trials with improved fish oil formulation (enteric-coated capsules) [74].

12. Depression and anxiety

Symptoms of depression include sadness, lethargy, and a general loss of interest in life [75]. Anxiety is also a common disorder and is characterized by constant worry and nervousness [76]. It is one of the most common mental disorders in the world. Interestingly, studies indicate that people who eat omega-3 s regularly are less likely to be depressed [77, 78]. What’s more, when people with depression or anxiety start consuming omega-3 supplements, their symptoms improve [79, 80]. ALA, EPA, and DHA are the three types of omega-3 fatty acids. Of the three, EPA seems to be the best at fighting depression [81].

13. Improving ADHD

Attention deficit hyperactivity disorder (ADHD)—characterized by impulsive behaviors and difficulty concentrating—generally starts in childhood but often continues into adulthood [82]. As the main omega-3 fat in your brain, DHA helps boost blood flow during mental tasks. Research has demonstrated that children and adults with ADHD commonly have lower blood levels of DHA [82, 83, 84]. In a recent review, seven of nine studies that tested the effects of DHA supplements in children with ADHD give some improvement—such as with regard to attention or behavior [85]. For example, in a large 16-week study in 362 children, those taking 600 mg of DHA daily had an 8% decrease in impulsive behaviors as rated by their parents, which was twice the decrease observed in the placebo group [86]. In another 16-week study in 40 boys with ADHD, 650 mg each of DHA and EPA daily alongside the children’s usual ADHD medication resulted in a 15% decrease in attention problems [87].

14. Metabolic syndrome

A metabolic syndrome is a group of conditions. It consists of central obesity—also known as belly fat—as well as high blood pressure, insulin resistance, high triglycerides, and low “good” HDL cholesterol levels. It is a major public health issue because it increases your risk of many other illnesses, including heart disease and diabetes [88]. Omega-3 fatty acids can help insulin resistance, inflammation, and heart disease risk factors in people with metabolic syndrome [80, 89, 90].

15. Skin health

DHA is a structural component of our skin. It is responsible for the health of cell membranes, which are up to a large part of your skin. A healthy cell membrane shows soft, moist, supple, and wrinkle-free skin. EPA also benefits the skin in several ways, including managing oil production, and skin hydration, and preventing hyperkeratinization of hair follicles, which appears as the little red bumps often seen on upper arms, reducing premature aging of your skin, reducing the risk of acne [91, 92]. Omega-3s can also save your skin from sun damage. EPA aids in blocking the release of substances that eat away at the collagen in your skin after sun exposure [91, 93].

16. Early preterm births

Delivering a baby before 34 weeks of pregnancy is known as early preterm birth and increases the baby’s risk of health problems [94, 95]. An analysis of two large studies shows that women consuming 600–800 mg of DHA daily during pregnancy decreased their risk of early preterm birth by more than 40% in the US and 64% in Australia, compared to those taking a placebo [96]. Therefore, it is especially critical to make sure that you are getting sufficient amounts of DHA when you are pregnant—either through diet, supplements or both.

17. Age-related cognitive decline (ARCD) and Alzheimer’s disease

Docosahexaenoic acid (DHA) has an important role in neural function. Decreases in plasma DHA are related to cognitive decline in healthy elderly adults and in patients with Alzheimer’s disease. A higher DHA level is inversely correlated with a relative risk of Alzheimer’s disease. Twenty-four-week supplementation with 900 mg/d DHA is reported to improve learning and memory function in ARCD and is a beneficial supplement that supports cognitive health with aging [97].

18. Kidney disorders

Researchers at the Mayo Clinic report that patients with IgA nephropathy have an abnormal EFA profile and that this abnormality can be corrected by supplementation with fish oil. The researchers conclude that fish oil supplementation retards the progression of IgA nephropathy [98]. Kidney transplant patients also benefit from fish oils [99].

19. Neuropathic pain

Pain is an electrical signal interpreted by one’s brain. Neuropathic pain or nerve pain is a chronic pain state that usually (but not always) is caused by some sort of tissue trauma. In neuropathic pain, the nerve fibers themselves get often damaged, dysfunctional, or injured. These damaged nerve fibers transmit incorrect electrical signals to the brain’s pain centers. The first-ever reported case series suggests that omega-3 fatty acids may be of benefit in the management of patients with neuropathic pain [100]. Long-chain omega-3 fatty acids supplementation accelerates nerve regeneration and prevents neuropathic pain behavior in mice [101]. Treatment with omega-3 PUFA could represent a promising therapeutic approach in the management of neurological injury [102].

20. Benefits for the aging brain

Brain volume shrinks with age [103], with a parallel decrease in DHA composition [104]. DHA is critical for healthy brain aging. With aging, your brain goes through natural changes, characterized by increased oxidative stress, altered energy metabolism, and DNA damage [105], while many of these changes are also seen when DHA levels decrease. These include altered membrane properties, enzyme activity, memory function, and neuron function [106]. Importantly, n-3 PUFA intake is positively correlated with gray matter volume in adults [107] and in brain regions responsible for cognition in normal, elderly adults [108]. Taking a supplement may help, as DHA supplements have been linked to significant improvements in memory, learning, and verbal fluency in those with mild memory complaints [108]. Environmental factors, such as diet, exercise, and DHA consumption, can positively affect the normal aging process and overall mental health and performance [109].

21. Benefits of asthma in children

Asthma is a chronic lung disease, which has symptoms like coughing, shortness of breath, and wheezing. Severe asthma attacks can have very dangerous attacks. They are characterized by inflammation and swelling in the airways of your lungs. Specialized pro-resolving mediators (SPM: protectins, resolvins, and maresins) are released from omega-3 fatty acids, such as EPA and DHA, via several enzymatic reactions. These mediators counter-regulate airway eosinophilic inflammation and promote the resolution of inflammation in vivo [110, 111]. Several studies link omega-3 consumption with a lower risk of asthma in children and young adults [112, 113].

22. Fat reduction in liver

Nonalcoholic fatty liver disease (NAFLD) is more common than you think. It has increased with the obesity epidemic to become the most common cause of chronic liver disease in the Western world [114]. However, supplementing with omega-3 fatty acids effectively decreases liver fat and inflammation in people with NAFLD [115].

23. Psychosis

In a study of 81 young patients with mild psychosis, low-dose omega-3 supplementation (1.2 g/day) significantly reduced the incidence of psychotic disorders [94]. Further trials should investigate this potential benefit of omega-3/fish oil.

24. Cachexia

Taking mega-doses (7.5–8.1 g daily) of fish oil slightly slowed down weight loss in 67 patients with cancer-related cachexia (severe weakness and wasting) [116, 117]. Lower doses (3 g daily) do not seem to have beneficial effects [118].

25. Aggression

DHA significantly reduced aggression due to mental stress in a study of 41 students. The same group of authors failed to confirm this benefit in non-stressful situations [119, 120]. In a 6-month study on 200 school children aged 8–16 years old, omega-3 supplementation caused a significant reduction in several measures of aggression [121].

26. Rheumatoid arthritis

Resolvins found in EPA and DHA appear to prevent certain inflammatory cytokines, such as TNF-α from inducing pain [122]. Long-term supplementation with fish oils benefits rheumatoid arthritis patients significantly and may lessen their need for NSAIDs and other RA medications [123]. Dietary fish oil supplements should now be regarded as part of standard therapy for rheumatoid arthritis [124, 125].

27. Osteoporosis and bone health

Osteoporosis and arthritis are two common disorders that affect your skeletal system. Studies show that omega-3 s can improve bone strength by boosting the amount of calcium in your bones, which should lead to a reduced risk of osteoporosis [126, 127]. Omega-3 s may also cure arthritis. Patients taking omega-3 supplements have been reported to have reduced joint pain and increased grip strength [128, 129].

28. Omega-3s and menstrual pain

Menstrual pain occurs in your lower abdomen and pelvis and often radiates to your lower back and thighs. It can significantly affect the quality of female life. However, studies repeatedly prove that women who consume the most omega-3s have milder menstrual pain [129, 130]. One study even determined that an omega-3 supplement was more effective than ibuprofen in treating severe pain during menstruation [131].

29. Good sleep

Good sleep is one foundation for good health. Low levels of omega-3 fatty acids are associated with sleep problems in children and obstructive sleep apnea in adults [131, 132]. Low levels of DHA are also linked to lower levels of the hormone melatonin, which helps you fall asleep [133]. Studies in both children and adults reveal that supplementing with omega-3 increases the length and quality of sleep [132, 133].

30. Blood pressure reduction and circulation help

DHA boosts good blood flow, or circulation, and may help endothelial function— the ability of your blood vessels to dilate [134]. A review of 20 studies found that DHA and EPA may also help in lowering blood pressure, though each specific fat may affect different aspects. DHA decreases diastolic blood pressure (the bottom number of a reading) by an average of 3.1 mmHg, while EPA helps lower systolic blood pressure (the top number of a reading) by an average of 3.8 mmHg [135].

31. DHA in sport nutrition

DHA may influence sports performance by improving aerobic processes and using fat as an energy substrate [136]. The applications of omega-3 supplementation for sports performance seem to be relevant for athletes involved in strength, endurance, and team-based activities. However, determining exactly how they work and how much omega-3s may benefit strength, endurance, and recovery is not confirmed. This is accomplished by enhancing the delivery of oxygen and nutrients and removing waste products from tissues. Postexercise recovery time may decrease due to reduced inflammation and increased release of growth hormones [137].

Walser et al. [137], reported that stroke volume and cardiac output increased during exercise when DHA + EPA were administered to subjects. This finding suggests that DHA + EPA may increase oxygen delivery during exercise [138]. Other researchers have shown that DHA + EPA supplementation improves circulatory function through. DHA supplementation improves minute heart rate recovery after exercise. Both of these DHA-related effects may contribute to better athletic performance and exercise recovery. DHA supplementation during exercise positively affects cognition and the strength of the connection between synapses in the brain [139].

32. DHA and skeletal muscle

Skeletal muscle disuse results in a reduction in fed and fasted rates of skeletal muscle protein synthesis, leading to the loss of skeletal muscle mass. Recent evidence has shown that supplementation with ω-3 fatty acids during a period of skeletal muscle disuse increases the ω-3 fatty acid composition of skeletal muscle membranes, heightens rates of skeletal muscle protein synthesis, and protects against skeletal muscle loss. Omega-3 fatty acid ingestion is a potential preventive therapy to combat skeletal muscle-disuse atrophy but additional, appropriately powered randomized controlled trials are now needed in a range of populations before firm conclusions can be made [140]. Following n3-PUFA supplementation, mixed muscle, mitochondrial, and sarcoplasmic protein synthesis rates were moved up higher in older adults before exercise. n3-PUFA boosts postexercise mitochondrial and myofibrillar protein synthesis in older adults. These results have shown that n3-PUFA reduces mitochondrial oxidant emissions, increases postabsorptive muscle protein synthesis, and enhances anabolic responses to exercise in older adults [141]. Enrichment of EPA and DHA in these membrane phospholipids is linked to enhanced rates of muscle protein synthesis, decreased expression of factors that regulate muscle protein breakdown, and improved mitochondrial respiration kinetics [141].

33. Men’s reproductive and sexual health

As wellness professionals would agree, fish oil does help with sexual performance and more. They would recommend filling up with the omega-3 in fish oil every day to be empowered sexually with maximum energy and drive. Neurons, photoreceptor cells, and spermatozoa are three cell types that show high DHA content. The structural integrity of the spermatozoa cell membrane plays a pivotal role in successful fertilization. This is because both the acrosome reaction and sperm-oocyte fusion is associated with the membrane’s fatty acid profile [142].

The majority of researchers have demonstrated that DHA (22:6n-3) is a major PUFA in human spermatozoa. Its deficiency is a typical sign in spermatozoa of subfertile or infertile men [143]. DHA comprises up to 30% of esterified fatty acids in phospholipids and 73% of all PUFAs and it gives proper fluidity to fertile sperm [142]. The percentage of DHA in sperm membrane phospholipids was higher than that of DHA in other cells. Hence, PUFA metabolism was more active in the testes during spermatogenesis and epididymal sperm maturation than these PUFA metabolism in other cells [144]. Interestingly, Zalata et al. have indicated that DHA in human spermatozoa may have specific functions unrelated to fluidity, which is similar to the functions of DHA in the brain and retina. More recently, it has been suggested that lipid concentrations may affect semen parameters, and this effect is more pronounced in sperm head morphology [145] Inadequate DHA concentration is the main cause of low-quality spermatozoa. Getting adequate DHA supports both the vitality and motility of sperm and improves sperm quality and function, which impacts fertility [142].

For erectile dysfunction, consuming a fish oil concentrate improves blood flow to the pelvis, reduces inflammation, and cuts the risk of tiny blood clots that impede erections. Highly absorbable omega-3 fats in a concentrate also stabilize hormone and neurotransmitter balance, for stronger erections that are sustained longer [146]. A healthy heart is a good sign of a functioning penis.

“Many of our male patients over the years are receiving enduring improvements in erectile dysfunction, taking a potent fish oil concentrate for at least 6 months.”—Dr. Rachelle Herdman.

34. Benefits for healthy hair growth

Fatty acids promote hair growth, as well as add sheen and luster to hair. A proper amount of omega-3 in your diet prevents dry, itchy, flaky scalp, and is beneficial in reversing hair loss [147].

35. Help in stem cells

Omega-3 fatty acids support stem cells [148]. The available evidence shows that n-6 and n-3 PUFA and their metabolites can act through multiple mechanisms to promote the proliferation and differentiation of various stem cell types [149].

36. Conclusion

In summary, the health benefits of DHA start from the baby’s formation in the mother’s womb and continue to the adolescent and adult stages up to aging for men and women, including sexual health. Higher DHA levels in body are associated with better mental, physical health, and performance enhancement while low level of DHA has been linked to physical and mental diseases that may cost huge financial burdens. So, DHA is a critical component for a happy life. There have been negative results in a few human trials of the effectiveness of omega-3 fatty acids starting from even CVD. However, the substantial literature of positive results outweighs the negative results. It will be wiser for us to keep the optimum level of DHA in our bodies throughout life. Indeed, it needs more research to verify them more.

Acknowledgments

Authors acknowledge gratefully the initiation of IntechOpen .com team for the book and the typist for his help.