by Craig Weatherby
When it comes to the risk of hypertension, adults tend to follow a path laid down decades earlier.
Ample evidence shows that having high blood pressure in childhood and adolescence predicts a greater chance of developing serious hypertension in middle age.
In addition to being overweight or under stress, a recent study revealed that sleep deprived teenagers—an increasingly kind—face risks of elevated blood pressure (Javaheri S et al. 2008).
So the results of a Danish clinical trial—in which omega-3s lowered overweight boys’ blood pressure—provide another reason for kids to get ample fish fats.
University researchers in Denmark recruited 78 mildly overweight adolescent boys aged between 13 and 15.
Like other slightly overweight teenagers, the volunteers had higher average blood pressure than their peers—at the high end of the normal range—and worse blood fat and sugar-control profiles.
Even though the boys did not actually have hypertension, they all had room to gain meaningful improvements in blood pressure and the other diabetes and cardiovascular risk factors measured by the Danish team.
There’s substantial clinical evidence that supplemental omega-3s can lower high blood pressure to a modest but significant extent (Cicero AF et al. 2009 and 2010).
As the author of a recent evidence review wrote, “There is substantial evidence that omega-3 fatty acids reduce blood pressure, with a greater effect in hypertensive patients and those with high-normal blood pressure” (Mori TA 2010).
The outcomes of the Danish trial seem to support that conclusion, and extend it to adolescent boys… with positive implications for their adult futures.
Four months of bread with fish fat yielded blood pressure benefits
The boys were randomly assigned to consume one of two breads daily for 16 weeks:
Control bread containing a vegetable oil with no omega-3s.
Test bread containing 1.5 grams of marine-source omega-3s (EPA and DHA)
At the end of the study, the boys who ate the omega-3-enriched bread daily had significantly lower average blood pressure, compared with the boys in the control group.
Specifically, systolic pressure averaged 3.8 mmHg lower and diastolic blood pressure averaged 2.6 mmHg lower in the omega-3 group.
The blood tests showed no changes in blood levels of triglycerides or insulin sensitivity.
While the omega-3 group showed small increases in HDL and non-HDL cholesterol levels compared with the control group, the researchers considered this unimportant.
As they wrote, “In this study, the non- HDL/HDL ratio, which is believed to be a better indicator of risk, was unaffected by the treatment, and thus the net effect [on blood fat profiles] appears to be neutral” (Pedersen MH).
Outcome attributed to omega-3s anti-inflammatory effect
To explain the trial’s main outcome, the researchers noted the competition between omega-3 EPA and DHA and the omega-6 fat called arachidonic acid (AA).
The body uses these long-chain omega-3 and omega-6 fats to make inflammation-related immune system chemicals called eicosanoids (eye-cose-uh-noyds).
Omega-6 AA tends to yield pro-inflammatory eicosanoids, while omega-3 EPA and DHA can only yield inflammation-easing eicosanoids.
The Danish team noted that the pro-inflammatory eicosanoids made from omega-6 AA tend to stimulate constriction of blood vessels, which would increase blood pressure.
In contrast, the anti-inflammatory eicosanoids the body makes from omega-3s (especially EPA) tend to help keep arteries relaxed and open.
Unfortunately, the average American diet provides far too many omega-6 fats—from common vegetable oils (corn, soy, safflower, sunflower, cottonseed) and the many packaged and prepared foods that include them—and far too few omega-3s.
While plant-form omega-3s are beneficial, they must be converted internally to EPA and DHA to be useful, at a very low rate of two to 10 percent.
The body makes far more efficient use of the omega-3 EPA and DHA in marine oils, as these are the fats it actually needs in its cells.
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Cicero AF, Derosa G, Di Gregori V, Bove M, Gaddi AV, Borghi C. Omega 3 polyunsaturated fatty acids supplementation and blood pressure levels in hypertriglyceridemic patients with untreated normal-high blood pressure and with or without metabolic syndrome: a retrospective study. Clin Exp Hypertens. 2010 Jan;32(2):137-44.
Cicero AF, Ertek S, Borghi C. Omega-3 polyunsaturated fatty acids: their potential role in blood pressure prevention and management. Curr Vasc Pharmacol. 2009 Jul;7(3):330-7. Review.
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