DHA and You

by Paulette Avery, R.N., M.S.N., I.B.C.L.C.

I suspect that your first reaction after reading the title of this month's column will be, "What is DHA?" The answer is docosahexaenoic acid, an omega-3 essential fatty acid that is vital to the growth and proper functioning of the brain and nervous system and also to good vision. Read on to find out more about this important substance and how to be sure you have as much as you need.

Wikipedia describes DHA as the most abundant polyunsaturated fatty acid (PUFA) in the brain and retina, comprising 40 percent of the PUFAs in the brain and 60 percent of the PUFAs in the retina. Although adequate DHA is important throughout the lifespan, it is especially important during pregnancy and breast-feeding, early childhood, adolescence, and the last two decades of life.

The most rapid brain growth in humans occurs during fetal development and the first year of life. In the first 12 months after birth, an infant's brain triples in size. Without adequate levels of DHA, poorer brain development and lowered visual acuity result. The fact that breast milk contains higher levels of DHA than formula may account for the higher IQs and better academic performance of breast-fed vs. formula-fed infants.

By adolescence, the brain has completed most of its growth, but important connections within the brain continue to develop at this stage. Because teens often eat diets high in saturated fats or may limit fat intake to increase athletic performance, they may not get all the DHA their brains need.'

Low levels of DHA have been associated with mental decline in older adults. A study by the Department of Veterans Affairs and UCLA found that a diet high in DHA slowed the progression of Alzheimer's disease by decreasing the harmful plaques in the brain. Adequate DHA appears to contribute to better heart health and may also decrease the development of macro degeneration, a serious condition that can lead to blindness.'

So there are plenty of reasons to maintain adequate levels of DHA. How do you do that? One of the best ways is through eating a diet high in omega-3 fatty acids found in cold water fish such as salmon and tuna, and in flax. But according to a talk I heard recently by nutritionist Monika Woolsey, MS, RD, all seafood can help you get the DHA you need. She recommended trout as another good source that is usually more available and less expensive than wild salmon. Just be sure to avoid fish known to have high mercury content, especially shark, swordfish, mackerel king, and tilefish. Flaxseed and canola oils also contain omega-3s.

Most experts recommend two four-ounce servings of coldwater fish each week. If you can't get enough through dietary sources, taking fish oil capsules is another option. Woolsey recommended 500 mg/day, but other experts suggest 300 mg/day for pregnant and lactating women and up to 1000 mg/day for people with cardiovascular disease. Along with increasing intake of omega-3s, most of us need to limit omega-6 fatty acids to achieve a healthy balance between the two. Eat fewer processed and fast foods, and use extra virgin olive oil instead of soy, safflower, corn, or cottonseed oils.

Paulette Avery is a registered nurse and a freelance writer who specializes in health issues.