Preventing Kidney Disease Is As Simple As That

At present, about 11% of the world's population, or 700 million people, suffer from chronic kidney disease (CKD), and the number of patients is increasing every year. Therefore, there is an urgent need for a method that can reduce the risk of CKD occurrence or progression. Previous studies have shown that omega-3 polyunsaturated fatty acids in marine organisms (hereinafter referred to as omega-3 fatty acids) may reduce the occurrence and development of CKD, which is beneficial to the prevention and treatment of CKD. 

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However, is this true? In addition, do unsaturated fatty acids in plants have the same effect?

On January 18, 2023, the BMJ published a pooled analysis from multiple countries showing that a higher intake of seafood-derived omega-3 fatty acids was associated with a reduced risk of CKD, while plant-based omega-3 fatty acids were not. Correlation1.

Method

The FORCE Research Consortium is a multinational research consortium aimed at studying the relationship between intake, circulating or body fatty acid content, and chronic disease. They pooled cohort studies conducted by different research groups to determine the relationship between omega-3 fatty acids and the risk of developing CKD.

A total of 19 studies from 12 countries were included in this meta-analysis. The primary endpoint was the incidence of CKD, defined as estimated glomerular filtration rate (eGFR)<60ml/min/1.73㎡. In addition, all participants included in the analysis had a baseline eGFR ≥ 60 ml/min/1.73㎡. The secondary endpoints analyzed were the change in eGFR and the proportion of patients with a ≥40% decline in eGFR.

Result

A total of 25,570 participants were included in 19 studies. The average age of the participants ranged from 49 to 77 years old, the average body mass index (BMI) ranged from 23.2 to 28.3kg/㎡, and the weighted average follow-up time was 11.3 years. The baseline eGFR of the study ranged from 76.1 to 99.8 ml/min/1.73㎡, and the average annual change in eGFR ranged from -6.2 to 0.3 ml/min/1.73㎡. A total of 4944 (19.3%) participants developed CKD.

A higher intake of omega-3 fatty acids in seafood can reduce the risk of CKD by 8% (RR=0.92; 95% CI, 0.86-0.98; P=0.009, I²=9.9%). After multivariate adjustment, the significance was No change (RR=0.91; 95% CI, 0.85-0.97; P=0.006, I²=17.2%). Compared with participants in the lowest 1/5 intake of seafood omega-3 fatty acids, the risk of CKD decreased by 13% in the highest 1/5 intake of seafood omega-3 fatty acids (RR=0.87; 95% CI, 0.80~0.96; P=0.005, I²=0.0%).

In a sequential analysis, seafood omega-3 fatty acid intake was not associated with a ≥40% reduction in eGFR. However, seafood omega-3 fatty acid intake can affect the rate of eGFR decline. Compared with participants in the lowest 1/5 intake, the decline rate of eGFR in the highest 1/5 intake was 0.07 ml/min/1.73㎡/year slower (95% CI, 0.02~0.13; P = 0.007; I²=42.2%).

It is worth noting that the study found that the intake of plant-based omega-3 fatty acids and flax oil did not change the risk of CKD (RR=1; 95% CI, 0.94~1.06; P = 0.94; I²=5.8%), and there were no significant differences in secondary endpoints.

Conclusion

This analysis showed that seafood intake of omega-3 fatty acids such as eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) is related to the risk of CKD, that is, the intake of more seafood omega-3 fatty acids can reduce the risk of CKD. However, flax oil intake was not associated with CKD risk.

Previous randomized controlled studies have found that increasing the intake of seafood omega-3 fatty acids can reduce blood pressure. The researchers believe that the lowering of blood pressure is the main reason for the lower risk of CKD. In addition, studies have confirmed that flax oil has little or no effect on lipids, glucose, and inflammation. 

Previous animal studies have shown that intake of EPA and DHA reduces fibrosis, inflammation, and oxidative stress. Increasing the production of endogenous DHA through transgenic technology can also reduce the level of renal fibrosis and inflammation in nephropathy mice with unilateral ureteral obstruction. However, little is known about DPA because there are few previous studies. However, DPA has been shown to have beneficial effects on cardiometabolic markers, although the evidence is limited.

Although flax oil is also an omega-3 fatty acid, it can be converted into long-chain omega-3 fatty acids (such as EPA and DHA) by enzymes in the body, but the catalytic rate of the enzyme is low. In addition, flaxseed oil intake was weakly correlated with blood levels, whereas EPA, DHA, and DPA had strong correlations. This may be related to the higher oxidation rate of linseed oil.

In this study, the source of omega-3 fatty acids was food (seafood), not food supplements. Previous studies have found that omega-3 fatty acid supplementation can improve blood lipid levels and reduce oxidative stress in patients with CKD. However, whether Omega-3 can delay the progression of CKD or the risk of CKD remains to be further studied. Researchers suggest that increased seafood intake may reduce intake of unhealthy diets such as red meat, which is associated with a greater risk of cardiovascular disease2 compared with white meat, and increased intake of omega-3 fatty acids Income can benefit the health of CKD patients in many ways1.

Overall, consuming more seafood rich in omega-3 fatty acids is beneficial to reduce the risk of CKD. In addition, studies have also shown that silver carp and bighead carp, which are freshwater fish in the Yangtze River Basin in China, are also rich in EPA and DHA, which are similar to tuna and salmon, which are higher in marine fish, but lower in cholesterol content3. This suggests that if it is difficult for residents in some areas of China to obtain marine fish rich in omega-3 fatty acids, they can also eat some freshwater fish.

for more information:Ali.ma@wecistanche.com