Women with High Intakes of Long-Chain Omega-3s May Have Fewer Strokes
There is considerable evidence, although some of it is inconsistent, that the consumption of fish or the long-chain omega-3 PUFAs (n-3 LC-PUFAs) they contain is associated with a lower risk of stroke in women. However, as one research group understated it, “the relationship between fish consumption and stroke risk is not straightforward.” These researchers reported that high consumption of salted fish was associated with a 2-fold greater risk of intracerebral hemorrhage compared with eating no salted fish. The high sodium intake of salted-fish-eaters probably contributed more to the stroke risk than the fish itself. In a study relevant to stroke risk, middle-aged Japanese men with high levels of serum DHA were more likely to have low carotid intima-media thickness scores compared with those having low DHA levels, suggesting that greater DHA intakes may reduce the risk of stroke.
Data from 34,670 Swedish women aged 49 to 83 years (average age 62 years) suggested that the consumption of more than 3 servings of lean fish per week, but not other fish, was associated with a 33% lower risk of stroke in women. In contrast, a study of women in southern Sweden reported that high intakes of lean fish were associated with a 63% increase in stroke risk in women, but greater consumption of fatty fish was associated with a 31% decrease in stroke risk among men and women. A meta-analysis of 15 prospective studies of fish consumption and stroke reported that fish consumption was only weakly associated with a reduced risk of stroke. These inconsistencies about such a prevalent condition demand resolution.
In this report, Swedish investigators assessed the relationships between total fat, specific fat classes and dietary cholesterol and the risk of stroke in the same cohort of nearly 35,000 women mentioned above. Dietary intakes were determined from a validated food frequency questionnaire with lifestyle habits and demographic data obtained from revisions to the original questionnaire. Stroke cases and deaths were identified from the Swedish Hospital Discharge Registry and classified as cerebral, intracerebral, subarachnoid or unspecified according to the International Classification of Diseases, 10th revision.
Over a follow-up period of 10.4 years, 1680 stroke events occurred, with 1310 cerebral infarctions (78%), 233 hemorrhagic (14%) and 137 (8%) unspecified strokes. The demographic data showed that participants in the highest quintile of n-3 LC-PUFA intake were more likely to be university-educated, had higher rates of diabetes, hypertension and a somewhat higher body mass index. They also consumed more alcohol, protein, monounsaturated and polyunsaturated fat and more cholesterol than women in the lowest category of n-3 LC-PUFA (EPA + DHA) consumption.
In multivariate analysis, high intakes of n-3 LC-PUFAs were associated with a significantly lower risk of total stroke (16% lower for the highest quintile of consumption)[frame src=”/wp-content/uploads/2012/04/PUFA4.12_Callout2.png” alt=”” width=”174″ height=”160″ align=”right” ] compared with the lowest quintile of intake (Table). Those with the greatest intakes consumed an estimated average of 730 mg/day compared with the lowest group at 144 mg/day. Those with the highest dietary cholesterol faced a significant 20% higher risk of total stroke and 29% greater risk of cerebral infarction. No other fat or fatty acid variables were associated with stroke risk in multivariate analysis.
These data support the previous report from southern Sweden in which higher consumption of fatty fish was inversely associated with stroke risk in women. They are consistent with several other prospective cohort studies in men and women, but not the US male physicians study, Chinese or Finnish studies. They confirm many previous reports linking high dietary cholesterol with greater stroke risk. While these findings do not settle questions arising from data inconsistencies, they suggest that n-3 LC-PUFAs may contribute to a modestly lower risk of stroke in women.
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