DHA products have long been available on the market and can be regarded as one of the most popular and widely accepted nutritional supplements. DHA is a natural nutrient that has undergone significant research, with application in clinical trials and is widely recognized by medical practitioners. Related long-term and large scale research has been ongoing since the 70's. Research on DHA covers all demographic segments of the population on its benefits including for overall health enhancement and therapeutic effects.
In November 2000, DHA was recognized by the US FDA (Food and Drug Administration) in that the authority allowed manufacturers to make a limited claim relating DHA to heart health. Nutritional supplements may now claim the benefit of "reducing the risks of coronary heart disease". Whilst many researchers felt that the clinical evidence should have allowed for broader claims, it is nevertheless a step in the positive direction.
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What is DHA?
DHA is an essential fatty acid (EFA). Nutritionists always remind us of the importance of diet based omega-3 consumption. DHA is not a fat but a kind of unsaturated fatty acid that is present in fish such as tuna, salmon etc. EFAs cannot be manufactured by the human body so that the only source is from food. The cerebral cortex, retina and breast milk contain relatively higher concentrations of DHA in human body. Since the 70's, scientists have found that Eskimos seldom suffer from cardiovascular diseases due to their diet of a large intake of unsaturated fatty acid from fish.
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Where does DHA come from?
DHA is an important element for building cells and the outer cell membrane. From birth, it is necessary for human body to obtain DHA from food so as to fulfill its needs. Deep-sea fish consume marine algae and smaller fish in the food chain thus accumulating larger amounts of linoleic acid (a precursor to DHA). Human obtains DHA by the intake of fish and other foods that contain DHA. Fat around eye socket of deep-sea fish contain one of the highest concentrations of DHA. Among fish species, fishes with brighter or shimmering skin such as bluefish, sardine, sturgeon, tuna and cod, contain more DHA. Meat and vegetables contain nearly zero percent of DHA. Thus, people who dislike eating fish are recommended to supplement DHA from other sources because inadequate intake of fatty acid is closely related to an increased risk of cardiovascular diseases.
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Fat and fatty acid
The July 1995 issue of a monthly magazine Nutrition Review in Italy carries a report about human health and fat released by the Committee on Food and Crops of the World Health Organization (WHO). This report states that fat is a key nutrient intake from food by human body but it only accounts for 15-35% of total energy consumption. For saturated fat (typically fat obtained from animal meat), the intake should not exceed 10%. For improved health, it is vital to obtain various fatty acids by taking fat in an appropriate way. On the other extreme, beauty fads may lead people to select low-fat foods but neglect the importance of taking enough fat to maintain health. Children going through the growth phase are not encouraged to have low-fat food. To get a better understanding of the significance of fat, we have to realize what EFAs (essential fatty acid) are.
EFA is a substance essential for the proper function of major organs and tissues in the human body. It is as crucial as water, vitamins, minerals, amino acids and oxygen. In the event of a deficiency, sufficient supplementation of EFA is essential for our daily needs. EFAs are polyunsaturated fatty acids that can be classes as omega-3, omega-6 and omega-9. Each of these has specific functions and is able to bring fat-soluble toxins deep in the body to skin surface for elimination.
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Functional value of DHA
Of the various health benefits associated with DHA, those related to heart function are the focus of the most attention in the medical community.
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- Enhance heart function:
In a 1988 edition of the British Journal of the Royal Society of Health, it was stated that DHA and EPA in fish oil contribute directly to the reduction of risks of having coronary heart disease and cardiovascular diseases. Similar reports also appeared in Japan, the US and Europe. Moreover, according to the US Epidemiology Periodical published in 1995, a clinical study lasting for 20 years concluded that high levels of DHA in the body can directly lower the probability of cardiovascular disease and high cholesterol levels in the patient research group.
Research on arteriosclerosis conducted in Taiwan suggests that this condition results from the accumulation of fat in blood vessels, which decrease the capacity of blood vessels, causing blockage and increased resistance to blood flow. The hardening of blood vessels and diminishing flexibility may lead to serious disease such as myocardial infarction and cerebral haemorrhage. Supplementation with DHA has an apparent preventative effect. DHA can also remove harmful fat in the blood, reduce blood pressure and minimize the crisis brought on by arrhythmia.
- Strengthen the functioning of brain and anti-aging.
By improving the delivery of nutrients to cells, EFA may prolong the lifespan of the cell and increase oxygen levels. DHA plays a crucial role in the functioning of the cerebral cortex, maintaining good memory as well as enhancing the development of the brain during the growth of a child. Our cerebral cortex consists of 10% DHA. DHA softens the structure of cell wall and facilitates the efficient transfer of messages. DHA is not only beneficial for growing children but also activates brain cells and slows down the aging process. It is also a powerful antioxidant.
- Protection for eye-sight
Sufficient DHA is present in the structure of the human retina so as to ensure normal eyesight. It is especially important for visual development in babies and infants. It may stimulate the light-sensitive cells so as to enhance eyesight. It is particularly beneficial in infants and the elderly.
- A treasure for pregnant women:
During pregnancy, the DHA level in mother's body affects the development of the fetus' head, the formation of cranial cells, eye tissue and heart. A number of studies point out that DHA supplementation in the third trimester of pregnancy (the last three months) and during the breast-feeding period can enhance the overall well-being of fetus and infant. It is now common to see milk powder with added DHA as one of its ingredients but the dosage in such forms may be relatively low.
- Fortify immune system:
Our immune system suffers when we are tired or stressed. Decline in immunity is common among adult smokers, patients with chronic illness, those on long-term medication and those suffering from different kinds of allergies. Supplementation with an appropriate amount of DHA leads to cell recovery and strengthens immunity.
The US Naturopathy Encyclopedia indicates that DHA can ease various skin allergies, inflammation and fibroma.
- Raise intelligence and calm down negative emotion:
There has been extensive research about the benefits of DHA for children's health including ADHD (Attention Deficit Hyperactivity Disorder). Reports on improving intelligence by DHA are also plentiful. The latest is an article written by Dr. Thomas Stuttaford in TIME magazine. He states that Britain is the first nation advocating the addition of DHA supplements into infant milk powder. Studies have shown that children with long-term intake of DHA have obvious advantages in learning skills and ability to concentrate, over those without DHA supplementation.
- Fair and delicate skin
DHA supplementation raises oxygen levels in blood so that skin can absorb oxygen and nutrients more effectively. With improved metabolism, the skin turns 'brighter'. By eliminating toxins in the deep layer of skin, DHA accelerates the renewal of skin reducing the 'dullness'. Research relating to fatty acids and obesity reveals that appropriate DHA supplementation supports a healthy metabolism and boosts the metabolic rate in fat cells. It minimizes the accumulation of fat thereby indirectly promoting weight control.
There are many other DHA related studies focusing on its impact in cases of diseases ranging from rheumatoid arthritis, albuminuria (derived from kidney disease) to depression. It is a good reflection of the significant nutritional value of DHA.