Healthy diets are good for the kidneys - not just the heart

NUI Galway’s Dr Andrew Smyth
Nov 17 2014 Posted: 10:12 GMT

A healthy diet may help protect our kidneys, according to a new study presented by NUI Galway researchers at a major conference in Philadelphia which comes to a close today. However, individuals must also pay particular attention to their sodium (salt) and potassium intake, according to the research, which analysed data from over 500,000 people.

Chronic kidney disease is estimated to affect over 300,000 people in Ireland, although many people with chronic kidney disease may be unaware that they have it. Recent data suggests that approximately 4,000 people in Ireland have end-stage kidney disease, the most severe form of chronic kidney disease, and need dialysis or a kidney transplant. Chronic kidney disease is associated with an increased risk of other medical conditions including cardiovascular disease (heart disease and stroke).

“Current guidelines for healthy eating focus primarily on preventing cardiovascular disease”, explains the lead author on the research, NUI Galway’s Dr Andrew Smyth, whose work is supported by the Health Research Board. “We completed this research work to explore if healthy eating may also protect from kidney disease. This is particularly important, as people with more advanced kidney disease may be advised to restrict their diet.”

The study indicates that dietary modifications may reduce the burden of chronic kidney disease. Dr Smyth said: “Our results suggest that a healthy diet may reduce the future risk of kidney outcomes. Importantly, it highlights the importance of looking at the whole diet, rather than just looking at healthy foods alone. The most benefit was seen from a healthy diet, containing plenty of healthy foods, low amounts of unhealthy foods, higher potassium and not too much sodium. As dietary modification is a low-cost, simple intervention, it offers the potential to significantly reduce the burden from chronic kidney disease, while also protecting from cardiovascular disease.”

Dr Smyth presented the initial findings of the study at Kidney Week 2014, the annual meeting of the American Society of Nephrology, which was attended by over 13,000 people. The study, which was called ‘Diet and Major Renal Outcomes: The NIH-AARP Diet and Health Study’, used data from a large US study (National Institutes of Health Diet and Health Study). Dr Martin O'Donnell of NUI Galway was the senior author on the report.  

Over 500,000 people aged 50-71, living in the United States, provided medical information and completed a diet questionnaire, which was used to measure how healthy each person's diet was at baseline (using four different scoring systems), as well as calculating each person's intake of sodium and potassium. Using available follow-up data, the researchers explored the association between diet and kidney outcomes, including the need for dialysis or dying with chronic kidney disease. During the study period, almost 5,000 people required dialysis or died with chronic kidney disease.

Using three of the four diet scoring systems, people with the highest scores for diet quality had the lowest risk of kidney outcomes. In these three scoring systems, people scored highly for eating plenty of healthy foods (such as fruits and vegetables) and for eating low amounts of unhealthy foods (e.g. deep fried, fatty or sugary foods). The biggest effects were seen with the scoring systems that focus on the whole diet. The fourth scoring system, which focuses only on healthy foods (Recommended Food Score), was not associated with kidney outcomes. In addition, the researchers found that high sodium intake was associated with an increased risk of kidney outcomes, as was low potassium intake.


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