Higher levels of omega-3 fatty acids in seafood were tied toa moderately lower risk of chronic kidney disease and a slower decline in kidney function, according to research from the University of New South Wales.
These associations were not seen with higher levels of plant-derived omega 3 fatty acids, such as ALA (alpha linolenic acid) found in walnuts, ground flax and chia and hemp seeds
Although the size of these associations was modest, the findings support current clinical guidelines that recommend adequate consumption of seafood and oily fish as part of healthy dietary patterns.
Animal studies suggest that omega-3 fats may have beneficial effects on kidney function, but evidence from human studies is limited and relies mainly on dietary questionnaires, which can be prone to error.
About the study
To explore this further, the researchers pooled the results of 19 studies from 12 countries, published up to May 2020, that investigated the links between levels of omega-3 fats and development of chronic kidney disease (CKD) in adults.
Specifically, the researchers measure levels omega-3 fatty acids called eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and alpha linolenic acid (ALA).
The main dietary sources of EPA, DHA and DPA come from seafood, while ALA is found mainly in plants (nuts, seeds, and leafy green vegetables).
CKD was identified by a measure of kidney function known as the glomerular filtration rate, which measures how well the kidneys are removing waste and excess fluid from the blood.
The findings
Overall, 25,570 participants were included in the analysis. In total, 4,944 participants (19%) developed CKD during an average monitoring period of 11 years.
After accounting for other a range of factors including age, sex, race, body mass index, smoking, alcohol intake, physical activity, heart disease and diabetes, higher levels of total seafood onega-3 fats were associated with a modest lower risk of developing CKD.
When participants were split by omega-3 levels, those with total seafood omega-3 levels in the highest fifth had a 13% lower risk of CKD compared with those in the lowest fifth.
Higher levels of total seafood omeg-3’s, especially DHA, were also associated with a slower annual decline in eGFR.
Plant-derived ALA levels were not associated with CKD.
These are observational findings and do not prove cause and effect. And they cannot rule out the possibility that some of the observed risk may be due to unmeasured factors.
Nevertheless, results were similar after further analysis, and appeared consistent across age groups (under 60 and over 60 years), high blood pressure, diabetes and coronary heart disease.
“Further randomised controlled trials are warranted to assess the potential beneficial role of seafood n-3 PUFAs in preventing and managing CKD,” they add.
Source: The BMJ, January 18, 2023.
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