Eating at least two servings of oily fish such as mackerel, sardines or herring per week is associated with a lower risk of chronic kidney disease and a slower decline in the organ’s function, research shows.
Chronic kidney disease (CKD) affects about 700 million people worldwide. It can lead to kidney failure and death, so there is an urgent need to identify factors that could prevent its onset and progression.
Now a study has found a link between higher levels of omega 3 fatty acids found in oily fish and other seafood and a reduced risk of kidney problems. No association was found with higher levels of plant omega 3 fatty acids.
The findings of the international team of researchers, led by the George Institute for Global Health and the University of New South Wales, were published in the medical journal BMJ.
“Although we can’t say for sure which specific fish had the biggest effect on CKD risk, we do know that fatty acid levels in the blood reflect their intake well,” said Dr. Matti Marklund, a senior research fellow at the institute. George, to the Guardian in an email.
“Among the richest dietary sources of these fatty acids are oily cold-water fish – such as salmon, sardines, mackerel and herring – and to a lesser extent shellfish such as oysters, clams and crab.”
The findings support guidelines recommending the consumption of oily fish and other seafood as part of a healthy diet.
“Current dietary recommendations in most countries suggest at least two servings of fish per week, preferably oily fish, which will provide about 250 mg/day of long-chain omega-3s,” Marklund said.
Animal studies have previously suggested that omega 3 fatty acids may help kidney function, but until now evidence from human studies has been limited – and mostly relied on dietary questionnaires.
The researchers pooled the results of 19 studies from 12 countries examining the links between omega 3 fatty acid levels and the development of CKD in adults.
About 25,000 people between the ages of 49 and 77 were included in the main analysis.
After accounting for a number of factors, including age, gender, race, body mass index, smoking, alcohol intake, physical activity, heart disease, and diabetes, higher levels of omega-3 fatty acids from seafood were associated with an 8% – low risk of developing CKD.
When participants were divided by levels of omega 3 fatty acids from seafood consumed, those in the highest quintile had a 13% lower risk of CKD compared to those in the lowest quintile. Higher levels were also associated with a slower annual decline in kidney function.
The researchers pointed out that their findings are observational and therefore do not prove that including more seafood in your diet definitely reduces the risk of CKD. “We need randomized controlled trials to determine this type of causal relationship,” Marklund said.
Nevertheless, the results were similar after further analysis and appeared to be consistent across age groups. “Higher levels are consistently associated with a lower risk of CKD,” he added.
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