DIET AND DHA

Role of docosahexaenoic acid (DHA) in children :

DHA is an omega -3 polyunsaturated essential fatty acid. The development of visual and neurological functions in infants has been demonstrated in various DHA studies. (1) In a randomized controlled trial in USA, it has been found that toddler formula supplemented with DHA improved RBC DHA status and lowered incidence of respiratory illness (p=0.024) compared to formula without DHA in children less than 3 years of age. (2) Thus role of DHA in infants and toddlers seems to be defined and adequate intake needs to be ensured.

Intake of DHA in children :

Eicosapentaenoic acid (EPA) and DHA intake is often low in 2-12 years old children relative to intake in breast fed infants and adult intake. It has been found that large proportions of children have low levels of intake of n-3 omega fatty acids with >97% of all groups consuming less than 1% energy from this fats due to poor intake of EPA & DHA. (3)

Consumption of healthy diets that contribute with adequate amounts of fat and fatty acids is needed to children. (3) Dietary intakes in childhood should support future adult health such as prevention of metabolic disorders & cardiovascular disease, support immune function and maintain healthy reproductive system (4).

DHA is predominant in fish and seafood and consumption of these foods in Indian children is virtually lacking. In vegetarians the predominant polyunsaturated fatty acid is linolenic acid (LA) - an omega 6 fatty acid. Alpha linolenic acid (ALA) which is an omega 3 fatty acid is not so abundant in vegetarian diets. (5) ALA is a precursor of EPA and DHA. The ideal ratio of LA to ALA should be 3:1 in the diet, however most diets have a ratio of 10:1 or 15:1. (5) Under these circumstances, omega 6 fatty acids inhibit the conversion pathway of omega 3 fatty acids. Thus decreasing LA content has been found to increase the ALA conversion to EPA and DHA.

Sources of DHA :

Foods with rich ALA content are rape seed oil, walnut and flaxseed oil. (5) Milk and cheese are good sources of omega – 3. Half a pint of milk provides 10% of recommended daily intake (RDI) of ALA. Although fish oils are rich sources of DHA, most commercially available fish oils contain higher amount of EPA than DHA. Most DHA found in extracted fish oil preparation is derived from microalgae consumed by the fish. Pure DHA from fish oil is not readily available in the commercial market due to difficulties in extraction and purification processes. Currently, the best commercial source of DHA is derived from microalgae by fermentation which is the vegetarian source of DHA. (6) This vegetarian source of commercial microalgae DHA may have to be supplemented in children to achieve adequate DHA content.

The DHA content in various foods is depicted in Table 1. :

Table 1: Dietary sources of DHA (7)

Source	Grams of omega – 3 fatty acid
Fish	(per 3 oz serving)
» Tuna	0.21 – 1.1
» Pollock	0.45
» Salmon	1.1 – 1.9
» Cod	0.15 – 0.24
» Catfish	0.22 – 0.3
» Flounder	0.48
» Grouper	0.23
» Halibut	0.60 – 1.12
» Mahi mahi	0.13
» Orange roughy	0.028
» Red snapper	0.29
» Shark	0.83
» Sword fish	0.97
» Tile fish	0.90
» King mackerel	0.36
Botanical sources	Percentage of omega – 3 in seed oil
Chia	64
Kiwifruit	62
Perilla	58
Flaxseed	55(18% of omega-3 in the whole food
Cow berry	49
Camelina	36
Purslane	35
Black raspberry	33
Hemp seed	19 (8.7% of omega 3 in the whole food)

Daily requirement of DHA (8) :

While exact dose of DHA to be consumed is not known, the following are recommended

• Pregnant and Nursing women – A workshop sponsored by the National Institutes of Health and International Society for the study of fatty acids and lipids (NIH/ISSFAL) recommended an intake of 300mg/day of DHA
  
  
• Children and Healthy Adults – NIH/ISSFAL have recommended an intake of 220 mg/day of DHA.
  
  

Conclusion :

Adequate amount of DHA is required in children for cognitive, visual, immunological effects. Intake of DHA from diet is often poor and thus supplementation of DHA may be required.

References :

1.	Gil-Campos M, Dalmau Serra J; Comité de Nutrición de la Asociación Española de Pediatría. Importance of docosahexaenoic acid (DHA): Functions and recommendations for its ingestion in infants. An Pediatr (Barc). 2010 Jun 4. [Epub ahead of print] Spanish
2.	Minns LM, Kerling EH, Neely MR, Sullivan DK, Wampler JL, Harris CL,et al. Toddler formula supplemented with docosahexaenoic acid (DHA) improves DHA status and respiratory health in a randomized, double-blind, controlled trial of US children less than 3 years of age. Prostaglandins Leukot Essent Fatty Acids. 2010; 82: 287-293
3.	Bermudez OI, Toher C, Montenegro-Bethancourt G, Vossenaar M, Mathias P, Doak C, Solomons NW. Dietary intakes and food sources of fat and fatty acids in Guatemalan schoolchildren: a cross-sectional study. Nutr J. 2010; 9: 20
4.	Koletzko B, Uauy R, Palou A, Kok F, Hornstra G, Eilander A, et al. Dietary intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in children - a workshop report. Br J Nutr. 2010; 103: 923-928.
5.	The Vegetarian Society - Information Sheet - omega 3. Available at URL: http://www.vegsoc.org/info/omega3.html. Accessed on 2nd July 2010
6.	http://www.martek.com/About/Martek-Products.aspx. Accessed October 23, 2009]
7.	Omega-3 fatty acid – Wikipedia, the free encyclopedia. Available at http://en.wikipedia.org/wiki/Omega-3_fatty_acid. Accessed on 2nd July 2010
8.	About Docosahexaenoic Acid, DHA Omega 3 Fats. Available at URL: http://www.lifesdha.com/About-DHA.aspx. Accessed on 2nd July 2010