(30-04-12) The Blood Pressure Solution from the Sea

by David Juan, MD

Everyone who pays attention to health news knows that omega- 3 fats in fish
are extraordinarily healthful. In my ongoing series on blood pressure, we find
that omega-3s could help those who suffer hypertension.

The inverse relationship between fish intake (specifically omega-3 fatty
acids) and heart disease was well established after we discovered that
inhabitants of Greenland had a low death rate from heart disease despite a fat-
rich diet. Later on, it was shown by large population studies that there is
also an inverse relationship between omega-3 fatty acids and the incidence of
stroke. This observation helps to fuel intensive research into the effect of
omega-3 fatty acids and their effect on blood pressure.

A meta-analysis found that omega-3s' effect on blood pressure is dependant on
dose. The minimal dose to be effective is three grams a day. The blood-pressure-
lowering effects in untreated high blood pressure were 5.5 mmHg (systolic blood
pressure) and 3.5 mmHg (diastolic blood pressure).

In a meta-analysis of 31 studies with 1,356 individuals, omega-3 fatty acids
lowered blood pressure again. Each gram of omega-3 led to a 0.66-mmHg and 0.35-
mmHg drop in systolic and diastolic levels, respectively. Whereas normal people
had no significant effects from omega-3, those with high blood pressure
experienced drops of 3.4 mmHg and 2.0 mmHg in systolic and diastolic levels.

In a meta-analysis of 36 studies with an average of 3.7 grams a day of omega-3
fatty acids, systolic blood pressure dropped by 2.1 mmHg and diastolic by 1.6
mmHg. The blood-pressure- lowering effects of omega-3s were more significant in
adults over 45 years and those with high blood pressure.

Now, there are two major omega-3 fats in fish -- eicosapentaenoic acid (EPA);
and docosahexaenoic acid (DHA) -- that have different effects on blood
pressure.

In one good study, 59 overweight patients were randomly assigned to get four
grams a day of purified EPA, DHA, or olive oil (placebo) capsules for six
weeks. Only DHA -- not EPA -- lowered blood pressure. Compared to the placebo,
DHA lower systolic blood pressure by 5.8 mmHg and diastolic blood pressure by
3.3 mmHg, and lowered heart rate.

In another study of 265 adults (between 30 and 54 years old), the effect of
modest variations of omega-3 fatty acid intake on blood pressure was studied.
The results: DHA again was the effective treatment, lowering diastolic levels
by 2.1 mmHg.

sources:Appel, L.J., et al., "Does supplementation of diet with 'fish oil'
reduce blood pressure? A meta-analysis of controlled clinical trials," Arch.
Int. Med., 1993; 153: 1,429-38.
Morris, M.C., et al., "Does fish oil lower blood pressure? A meta-analysis of
controlled trials," Circulation, 1993; 88: 523- 33.
Geleijnse, J.M., et al., "Blood pressure response to fish oil supplementation:
met regression analysis of randomized trials," J. Hypertens., 2002; 20: 1,493-
9.
Mori, T.A., et al., "Docosahexaenoic acid but not eicosapentaenoic acid lowers
ambulatory blood pressure and heart rate in humans," Hypertension., 1999; 34:
253-60. Liu, J.C., et al., "Long chain omega 3 fatty acids and blood pressure,"
Am. J. Hypertens., 2011; 24: 1,121-6.

News

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In evidenza

"L'informazione presente nel sito serve a migliorare, e non a sostituire, il rapporto medico-paziente."

Per coloro che hanno problemi di salute si consiglia di consultare sempre il proprio medico curante.