The Health Benefits of DHA
Docosahexaenoic acid, or DHA, is a polyunsaturated omega-3 fatty acid found throughout the body. It is a major structural fat in the brain and retina accounting for up to 97% of the omega-3 fats in the brain and up to 93% of the omega-3 fats in the retina. It is also a key component of the heart. Numerous studies confirm that everyone, from infants to adults, benefits from an adequate supply of DHA.
DHA omega-3 is naturally found throughout the body and is most abundant in the brain, eyes and heart. DHA is critical for healthy brain and eye development and function and has been shown to support heart health from infancy through adulthood.
DHA serves as a primary building block for the brain and the eye. Just as calcium is essential for building strong bones, DHA ensures that the cells in the brain, retina, heart, and other parts of the nervous system develop and function properly.
DHA plays an important role in the following:
• Memory function
• Brain and central nervous system development and function
• Psychomotor development (such as eye-hand coordination)
• Visual development and function
• Heart health
• Nerve signal transmission
Understanding the Role that Each Omega-3 Plays: Today, more and more food products claim to be a good source of omega-3s, but not all omega-3s are created equal. There are three major omega-3 fatty acids: DHA, EPA and ALA. Each one plays a distinct role in the body.
The Benefits of DHA Throughout the Lifecycle
Docosahexaenoic acid, DHA, is an omega-3 fatty acid that is found throughout the body. More specifically, it is a major structural fat in the brain and eyes and a key component of the heart. Numerous studies confirm that everyone, from infants to adults, benefits from an adequate supply of DHA.
• Maternal Health
• Infant Development
• Beyond Infancy
• Adult Health
The Importance of DHA in maternal Well-Being
DHA is a major structural fatty acid in the brain and retina, and is naturally found in breast milk. It is important for a mother to consume adequate amounts of DHA during pregnancy and while nursing to support her well-being and the health of her infant.
• DHA supplementation during pregnancy was shown to increase the length of gestation by about six days helping mothers carry to a healthy or full term.
• Increasing dietary intake of DHA during pregnancy and postpartum may help to support a mother's emotional well-being.
• Maternal DHA supplementation resulted in mental development advantages in children including improved psychomotor development (such as eye-hand coordination) at 2.5 years of age and improved attention skills at 5 years of age.
• A study using a statistical model of risk-benefit, designed by Harvard Center for Risk Analysis, estimated that increasing maternal DHA intake by 100mg/day increases child IQ by 0.13 points.
DHA in Infant Development
• DHA is important for healthy visual and mental development throughout infancy. Studies with both preterm and term infants suggest that adequate DHA nutrition, provided through either breastmilk or DHA-fortified formula, is associated with optimal mental and visual development and function.
• Major brain growth occurs during the second trimester of pregnancy and throughout the first two years of life. During these times, the infant has the greatest need for DHA.
• Developing infants cannot efficiently produce their own DHA.
• DHA and ARA supplemented infant formula was shown to be a good source of these nutrients for formula-fed babies and has been recommended for inclusion in infant formulas by several scientific bodies worldwide.
DHA Beyond Infancy
• DHA is important for ongoing brain growth and development in children. It is also important for brain, eye and heart function throughout life. The body will continue to turn over DHA throughout the lifecycle and it is important to replenish the stores of DHA in our bodies. While the body can convert DHA from its precursor fatty acids, this process is inefficient and varies from person to person. It is therefore important for children (and adults) to obtain adequate amounts of DHA directly from their diet.
• During the early childhood years (ages 2 and 6) the brain and eyes experience significant growth. In fact, between birth and 5 years of age, the human brain increases approximately 3.5-fold in mass and DHA content increases from 1 gram to approximately 4.5 grams. Due to the major growth during this time and because DHA represents up to 97% of the omega-3 fatty acids in the brain and up to 93% of the omega-3 fatty acids in the retina, the brain and eyes have significant requirements for preformed DHA.
DHA in Adult Health
• DHA is important for ongoing brain, eye and heart health. It is also important for brain, eye and heart function throughout life. Throughout our lifecycle, the body will continue to turnover DHA and it is important to replenish the stores of DHA in our bodies. While the body can convert DHA from its precursor fatty acids, this process is inefficient. It is therefore important for adults to obtain adequate amounts of DHA in their diets.
Brain and Eye Health
• DHA is the predominant omega-3 fatty acid in the brain and eyes and is necessary for the optimal structure and function of nerve cells in the brain and eyes. In the brain, DHA is especially concentrated in the region responsible for complex thinking skills.
• A recently published large, randomized, placebo-controlled nutritional study in Alzheimer's & Dementia: The Journal of the Alzheimer's Association has demonstrated the benefits of algal DHA in improving memory in older adults. This study found that the cognitive improvement demonstrated by the DHA supplemented group was equivalent to having the learning and memory skills of someone more than three years younger.* No study using a fish oil source of DHA has found this significant benefit.
• A scientific review on DHA stressed the significant role that DHA plays in the maintenance of normal neurological function.
• There is preliminary research exploring the possible role of DHA in neurological function. Promising results from animal model and human-cell model studies suggest DHA may play a role in reducing the risk of certain neurological diseases. Additional research in humans is needed to evaluate the effect of DHA supplementation on preventing or treating these neurological disorders. Further research is also needed to determine the exact mechanism of action. A Japanese animal-model study found that DHA supplementation reduced the increase in number of reference and working memory errors and increased the antioxidative defenses suggesting DHA as a possible agent for ameliorating learning deficiencies due to Alzheimer's.
• The results of a human-cell model study showed that DHA intake may lower the accumulation of a protein that is associated with brain aging and Alzheimer's disease.
• An animal-model study showed that DHA may protect against the accumulation of a protein believed to be linked to Alzheimer's disease.
Cardioprotective Effects of DHA
• DHA is also a key component of the cardiovascular system. In the past 25 years, there have been over 4,500 studies of the cardiovascular effects of long-chain omega-3 polyunsaturated fatty acids, such as DHA.
• Although the exact relationship between DHA and the cardiovascular system is still being studied, observational and intervention studies support an association between DHA and good cardiovascular health.
• Based on the current body of research, several scientific bodies have made recommendations regarding the intake of omega-3 fatty acids and good cardiovascular health.
Controlling Blood Lipids
• Controlling blood lipids (total cholesterol, low density lipoprotein (LDL or "bad" cholesterol), high density lipoprotein (HDL or "good" cholesterol)) and triglycerides is important for reducing the risk of developing heart disease.
• One of the cardioprotective effects of DHA appears to be helping to normalize certain blood lipids. Three independent research studies in subjects with normal blood lipids have demonstrated a statistically significant drop (14-26 percent) in triglycerides and a trend toward higher HDL levels over baseline lipid levels after supplementation with high doses of DHA (more than 1.5g DHA/day) for 2-15 weeks. A fourth study showed similar blood lipid changes in the DHA group compared to the placebo group.
Controlling Blood Pressure
Controlling blood pressure is also important for maintaining cardiovascular health. One study found that DHA had modest blood pressure lowering effects in mildly hyperlipidemic men. Multiple human trials report small reductions in blood pressure with intake of omega-3 fatty acid.
• 5 to 6 mmHg in systolic pressure and 3 to 5 mmHg in diastolic pressure
- Dose: 3-6 grams of n-3 fatty acids (EPA plus DHA) over 6 weeks. DHA may have greater benefits than EPA
Cancer prevention
• Epidemiological studies have shown a reduced risk of developing breast, colon, or prostate cancer. DHA and EPA inhibited growth and metastasis of breast cancer cells in animal study. DHA directly suppressed arachidonic acidinduced colon cancer cell growth
Dietary Sources of DHA: Dietary sources of DHA include:
• Algae - Certain algae are natural sources of DHA. And while most people believe that fish produce their own DHA, in fact, it's the algae they feed on that make them a rich source of DHA.
• Seafood/Fatty fish,Walnuts, Wheat germ oil,Flaxeed oil/canola oil, Fish liver oils
• Organ meat such as liver,Small amounts are found in egg yolks are the good sourses of DHA.
Other Vegetable Sources
Grams/100 g edible portion
• Flaxseed 22.8g
• Walnuts 3.3 - 6.8g
• Soybeans (roasted) 1.5g
• Soybeans (raw) 3.2g
• Oats (germ) 1.4g
• Seaweed (spirulina) 0.8g
(Adapted from: Kris-Etherton et al. Polyunsaturated fatty acids in the food chain in the US. Am J Clin Nutr. 2000;71:180S).
Recommendations: For Infants & Children
• The American Academy of Pediatrics recommends that infant milk formula should provide at least 2.7% of total kilocalories in the form of linoleic acid.
• Of note, human milk provides 3.5% to as high as 12% of total kilocalories in the form of linoleic acid depending on the fat composition of the maternal diet.
For Infants and Children
0-6 months 0.5 g/day of n-3 PUFA
7-12 months 0.5 g/day of n-3 PUFA
1-3 yrs 0.7 g/day of a-linolenic acid
4-8 yrs 0.9 g/day of a -linolenic acid
Boys
9-13 yrs 1.2 g/day of a -linolenic acid
14-18 yrs 1.6 g/day o a-linolenic acid
Girls
9-13 yrs 1.0 g/day of a -linolenic acid
14-18 yrs 1.1 g/day of a -linolenic acid
Food and Nutrition Board, Institute of Medicine (FNBIOM,2001)
Recommendations: For Adults
• Requirements for EFAs are 1 to 2% of dietary calories for adults.
• Recommended 0.2% to 1% of total calories should be provided by omega-3 fatty acids.
For Adults
Men
19- >70 yrs 1.6 g/day of a-linolenic acid
17 g/day of linoleic acid
Women
19- >70 yrs 1.1 g/day of a-linolenic acid
12 g/day of linoleic acid
Food and Nutrition Board, Institute of Medicine (FNBIOM,2001)
No comments:
Post a Comment