|Is DHA supplementation safe in children?|
|Current research even with high dose DHA has not reported any serious adverse effects in children.
|Are there vegetarian sources of DHA?|
DHA in fish oil is also made from microalgae.
Several vegetable oils are rich in omega-3 PUFA namely, flaxseed or linseed oil, rapeseed oil , canola oil, peanut oil, olive oil, soya oil, walnut oil. However availability of DHA through these would be variable as they tend to have more of alpha-linolenic acid. Over the past few years, commercial sources of algae have been developed such that the algal oil derived from there does contain DHA which is of vegetarian origin.
|What is the upper limit of DHA intake?|
|Various health agencies from different countries have recommended intakes of DHA/EPA (combined) for optimal health during adulthood ranging from 300-650 mg per day. Children aged 4-8 years should consume at least 900 mg of ALA (alpha-linolenic acid) per day and may consume up to 10% of that (90 mg / day) as DHA + EPA. The Food and Drug Administration in the US have indicated that up to 3000 mg of DHA/EPA per day from all sources (diet + supplements) is generally considered safe for most adults.
|Does cooking decrease the DHA content of food?|
|Very little or no significant reduction in the percentages of DHA in the total fat occurs with normal cooking procedures
|If a mother cannot breast feed her child, is it necessary to give infant formula fortified with DHA?|
|The American Dietetic Association and the Dietitians of Canada have recommended that all infant formula should provide DHA during the first year of life to infants who are not being breastfed for whatever reason
|What are fatty acids? |
|Not to be confused with fats, fatty acids are chains of carbons with hydrogen attached to them and an “acid” group at one end of the molecule. Individual fatty acids serve different purposes in the body—some are “burned” or oxidized for energy, some are structural features of cell membranes, others are converted to different fatty acids or substances, such as sterols, while still others perform special duties in tissues, such as nerve cells.
Fatty acids also differ in the length of the carbon chain. Short-chain fatty acids have less than eight carbons. Medium-chain fatty acids have 8 to 14 carbons and long-chain fatty acids have 16 or more carbons.
|Types of Fatty Acids? |
|Fatty acids belong to one of three types or families: saturated, monounsaturated and polyunsaturated.
Saturated Fatty Acids :
The carbons in these fatty acids are fully loaded with hydrogen, thus forming straight chains. Saturated fatty acids stack tightly, providing rigidity and making food fats, such as butter, solid at room temperature. They have a similar effect in cell membranes. Many saturated fatty acids increase blood cholesterol levels and for that reason have been considered less healthful
Unsaturated Fatty acids :
These are called unsaturated because they have lost one or more pairs of hydrogen from their carbon chain. Unsaturated fatty acids include mono- and polyunsaturated fatty acids (PUFAs). When hydrogen pairs are removed, the fatty acid molecule develops a kink or bend, known as a double bond. The more hydrogen missing, the more bent out of shape the fatty acid becomes. Unsaturated fatty acids, especially those with several double bonds, occupy more space, thereby making a fat containing them liquid (an oil) and cell membranes more fluid.
Monounsaturated Fatty Acids :
These fatty acids are missing one pair of hydrogen, creating one double bond.
Polyunsaturated Fatty Acids (PUFA):
If two or more double bonds occur in the fatty acid, it is called "polyunsaturated."
|What are essential fatty acids?|
|Essential Fatty Acids are the "good fats". These are PUFAs necessary fats that humans cannot synthesize or derive from other fatty acids and must be obtained through diet. Traditionally, linoleic acid (omega-6) and, more recently, alpha-linolenic acid (ALA) (omega-3) were the only PUFAs considered essential because deficiency symptoms develop in their absence, it is the long-chain derivatives—arachidonic acid and DHA-that are the most critical for the body’s needs.
Some Fatty acids can be produced by our body those are called the non-essential fatty acids and no extra dietary supplementation for them is required. Both Essential fatty acids and their derivatives (DHA and arachidonic acid) are required by the body for proper functioning, growth and development.
|What are omega fatty acids? |
|They are essential fatty acids .They are component of fats that we consume, they are necessary for human health but the body can’t make them we have to get them through food. Also known as polyunsaturated fatty acids (PUFAs), omega-3 fatty acids play a crucial role in brain function, as well as normal growth and development. They have also become popular because they may reduce the risk of heart disease. |
|What are omega-3 and omega-6 fatty acids?|
|The end of the fatty acid farthest from the acid is called the omega end. The location of the first double bond counted from the omega end denotes whether a fatty acid belongs to the omega-6, omega-3 or other omega family. Humans cannot convert omega-3 and omega-6 fatty acids to each other, nor can they make either of these fatty acids from scratch.
These are two forms of fatty acids which differ in their chemical structure and also in their actions, one promotes inflammation (omega-6) and other reduces inflammation (omega-3). A correct ratio of omega-3/omega-6 is required in the body for optimal maintenance of metabolic functions.
These come in short- and long-chain varieties. The short-chain form is alpha-linolenic acid, the only omega-3 found in plants (except for some algae). It has 18 carbons and 3 double bonds. It is found in flaxseed oil (53%), canola oil (11%), English walnuts (9%), and soybean oil (7%). Alpha-linolenic acid is considered essential because we cannot make it and we need it or its long-chain derivatives. DHA is derived from ALA and is an important omega-3 fatty acid. Docohexaenoic acid (DHA) is the most abundant omega-3 long-chain polyunsaturated fatty acid (LC-PUFA) in the brain and retina and is essential for brain development in children and for vision.
Like omega-3, this family of PUFAs has its short-chain representative, linoleic acid. Considered essential in its own right for healthy skin, it predominates in several vegetable oils, namely corn, sunflower, soybean and canola oils. Linoleic acid is converted to a limited extent to the long-chain fatty acid, arachidonic acid, which has 20 carbons and four double bonds. Arachidonic acid is a vital constituent of cell membranes and an important source of substances involved in combating infection, generating protective inflammatory responses and promoting blood coagulation. It also has important functions in the communication between and within cells.
|Sources of omega fatty acids|
|Fish, plant, and nut oils are the primary dietary source of omega-3 fatty acids. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are found in cold water fish such as salmon, mackerel, halibut, sardines, tuna, and herring. ALA is found in flaxseeds, flaxseed oil, canola (rapeseed) oil, soybeans, soybean oil, pumpkin seeds, pumpkin seed oil, purslane, perilla seed oil, walnuts and walnut oil.
In infants, breast milk is a good source of DHA. Breast milk content of DHA depends on intake of DHA and its stores in the mother. Fish oils are rich in DHA. Most of the DHA in fish and other organisms originate from microalgae. ALA is present in vegetable oils such as flaxseed or linseed oil, rapeseed or canola oil, peanut oil, olive oil, soya oil, walnut oil, green leafy vegetables, fenugreek seeds, kidney beans and dry fruits. DHA is also manufactured from microalgae in vegetarian form for commercial use. Inadequate intake of n-3 PUFA decreases DHA and increase n-6 PUFA in the brain. Western diets as well as diet in developing countries are low in n-3 PUFA (7) whereas consumption of n-6 fatty acids is higher. The ideal ratio of n-6 and n-3 PUFA in diet should be 5-10:1 for optimal health benefits.
Table 1: Dietary sources of DHA
|Source||Grams of omega - 3 fatty acid|
• Mahi mahi
• Orange roughy
• Red snapper
• Sword fish
• Tile fish
• King mackerel
|(per 3 oz serving)|
0.21 - 1.1
1.1 - 1.9
0.15 - 0.24
0.22 - 0.3
0.60 - 1.12
Percentage of omega - 3 in seed oil
|Flaxseed||55(18% of omega-3 in the whole food|
|Hemp seed||19 (8.7% of omega 3 in the whole food)|
|Why is DHA so important in the retina?|
|DHA is a critical part of retinal structure. Its presence enhances the development of photoreceptors, specialized cells in the retina necessary for vision. High DHA concentrations are needed for rhodopsin—a pigment in the photoreceptor rod cells—to respond to light in a way that permits vision in dim light and at night. The highly unsaturated nature of DHA has unique effects on retinal cell membranes allowing them to transmit light signals very quickly.|
|How is DHA important for the brain?|
|Docosahexaenoic acid (DHA) is the most abundant omega-3 (n-3) long-chain polyunsaturated fatty acid (LC-PUFA) in the brain and retina. It constitutes 40% of the PUFA in the brain & 60% of the PUFA in the retina. Docosahexaenoic acid (DHA) is an omega-3 long chain polyunsaturated essential fatty acid which is important constituent of the membrane of the nerves in the brain. In young children, it enhances the brain development and cognitive functions whereas in older age it decreases progression of Alzheimer's disease.|
|How does DHA act on the brain?|
|DHA is an important constituent of membrane of the neurons. Low DHA levels increases risk of early death of the neurons. It has been found that total n-3 and n-6 polyunsaturated fatty acids increase in the whole forebrain during the prenatal and post natal period upto at least 2 years of age. Low maternal DHA is linked to poor child neural development and improving maternal DHA by supplementation decreases that risk. Human milk is a good source of DHA provided maternal DHA levels are normal. In young children, neurodevelopment and cognitive abilities are also enhanced by early provision of n-3 LC PUFA through milk or DHA fortified foods.|
|How does brain growth occur in children?|
|The human brain begins forming by 3rd week of pregnancy and 100 billion neurons are formed during first 5 months of gestation. New neurons are produced throughout life though far less rapidly and probably in numbers sufficient only to replace those that gradually die off. However brain size increases more gradually; a newborn’s brain is only quarter the size of an adult (about 360-380 gm), grows to about 80% of adult size by three years of age (1090-1270 gms) and 90% by 5 years of age. Adult brain size is 1170-1310 gms. Thus brain development is most sensitive to a child’s nutrition in fetal period, in first 2 years of life and early childhood. Because of rapid brain growth, children need a higher level of fat and fatty acids in their diet. With DHA being an important part of the neuron membrane, adequate DHA content is crucial for brain development.|
|How does maternal nutrition affect infant development?|
|Adequate dietary intake of DHA is particularly important for pregnant and nursing women. Significant brain and eye development occurs in utero and continues during the first year after birth.
Infants rely on their mothers to supply DHA for the developing brain and eyes initially through the placenta and then through breast milk. DHA is the most abundant omega-3, long chain fatty acid in breast milk, and studies show that breast-fed babies have IQ advantages over babies fed formula without DHA.
Women need sufficient stores of DHA for the proper nourishment of their babies during pregnancy and while feeding. Evidence points to the need for them to build up their stores ahead of the actual need. Infants of mothers who consumed DHA regularly during pregnancy have higher levels of DHA than infants of mothers consuming little DHA. These infants also have more DHA in their body fat, which provides insurance against a possible low intake after birth. Starting life with higher DHA is an advantage for the young infant whose brain grows for at least the next two years.
|How important is breast feeding?|
Breast feeding is the only source of nutritional supplementation in a newborn and has marked advantages over formula feeds. Most of the formulae feeds are deficient in long chain fatty acids (DHA is most important of them) and play a pivotal role in growth, development and functioning of human brain as the maximum potential of brain growth is during the first 24 months of life.