Study illuminates heart-protective function of key omega-3 in fish fat
by Craig Weatherby
One of the saddest side effects of America’s high-calorie, high-fat, super-sedentary lifestyle is its impact on children.
In addition to unprecedented rates of “adult” diabetes in children, we are seeing warning signs of cardiovascular disease in children, including imbalanced cholesterol levels, and dysfunction in the endothelial cells lining their arteries. Researchers in Britain, where diets and lifestyles resemble ours, found that the arteries in 20 per cent of 11-to-14 year olds they examined showed signs deterioration.
Childhood cholesterol levels were not well-established until fairly recently but experts now believe that high cholesterol in children may be common. Recent UK research revealed that 20 per cent of a group of 11-14 year olds were already experiencing deterioration in their micro-vascular health.
Vascular deterioration or imbalanced cholesterol levels will raise a child's chances of later developing cardiovascular disease (CVD). We lack research showing that statins—drugs that lower cholesterol levels, reduce inflammation, and improve vascular endothelial cell function—are safe for children, so dietary changes and exercise is the usual treatment for signs of incipient CVD in kids.
Researchers at the University of California, San Francisco knew that both fish oil and DHA supplements improve blood vessel function in adults. They wanted to know if DHA could help blood vessel function in children who had high blood fat and cholesterol levels as a hereditary condition. Twenty children between nine and 19 suffering from inherited imbalances in blood fat and cholesterol levels were recruited for a placebo-controlled, double-blind clinical study.
The children followed a heart-healthy diet and were assigned randomly to receive either 1.2 grams of DHA or a placebo daily for six weeks. This phase was followed by a non-treatment phase lasting six weeks, and a six-week “crossover” phase in which the DHA group got the placebo, and vice versa.
Blood vessel function in the children receiving DHA was restored to normal. Specifically, a marker of blood vessel function called endothelium-dependent flow-mediated dilation (FMD) increased significantly after DHA supplementation compared to the heart-healthy diet alone or placebo.
The NIH-funded researchers believe that DHA may improve the synthesis or release of nitric oxide previously observed in a study of the effect of fish oil supplements on human endothelial cells.
As the researchers concluded, “This study demonstrates that DHA supplementation restores endothelial-dependent FMD in hyperlipidemic [i.e., high-cholesterol] children. The endothelium (inner arterial lining) may thus be a therapeutic target for DHA… with the potential for preventing the progression of early coronary heart disease in high-risk children.”
What does this mean for healthy children? It suggests that they might enjoy preventive benefits form eating the twice-weekly servings of fish that US health authorities recommend. Just be sure to steer clear of high-mercury species, as identified in these joint EPA/FDA guidelines:
- Do not eat Shark, Swordfish, King Mackerel, or Tilefish because they contain high levels of mercury.
- Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury. Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish.
- Another commonly eaten fish, albacore ("white") tuna has more mercury than canned light tuna. So, when choosing your two meals of fish and shellfish, you may eat up to 6 ounces (one average meal) of albacore tuna per week. [NOTE: Vital Choice young, troll-caught albacore is low in mercury, which accumulates in tuna as they grow old.]
- Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas. If no advice is available, eat up to 6 ounces (one average meal) per week of fish you catch from local waters, but don't consume any other fish during that week.
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- What You Need to Know about Mercury in Fish and Shellfish. Accessed online April 16, 2005 at http://www.epa.gov/waterscience/fishadvice/advice.html