Can a diet rich in fruit and vegetables help the kidneys over the long term?

• Kidney disease is a problem for some people with HIV, particularly as they grow older
• A study of 1,608 women with HIV analysed the impact of diet and other factors on kidney health
• Researchers found that a diet rich in fruit and vegetables was good for kidney health

Thanks to the power of HIV treatment (antiretroviral therapy, ART) researchers expect that many ART users will have near-normal life expectancy. However, as ART users age, like everyone else, they will develop an increased risk for certain conditions associated with aging, including type 2 diabetes and high blood pressure. These conditions contribute to an increased risk for kidney disease.

The potential role of diet

Some research suggests that the diet typically consumed in many high-income countries—which is high in meat, grains, simple carbohydrates and saturated fat, and low in fibre, fruit and vegetables—may contribute to an increased risk for a range of problems, including kidney disease. In theory, this type of diet may lead to a relative excess of acid (vs. alkali or base) in the body. One of the functions of the kidneys is to maintain a relative balance of acid-base in the body. Research in animals suggests that, over time, a diet that is high in acid may weaken the kidneys. Such diets appear to contribute to higher levels of inflammation. An acid-base imbalance in the diet and its effect on kidney health is an emerging field of study.

About the study

A team of researchers at leading academic medical centres across the U.S. is involved in many studies with HIV-positive women. In one of these studies, researchers studied the impact of diet on kidney health. The study took place between 2013 and 2016 and used data collected from 1,608 women. The researchers regularly interviewed the women and collected blood and urine samples for analysis. At the start of the study, all the women were taking ART, and on average they had a suppressed viral load (less than 40 copies/mL) and a CD4+ count of nearly 600 cells/mm³. Overall, the women had a low daily consumption of fruit and vegetables—between one and two servings daily.

Results

Statistical analysis found that women with the highest intake of fruit and vegetables—at least five servings daily—had the slowest decline in kidney function.

Fruit, vegetables and inflammation

The researchers analysed participants’ blood samples for proteins associated with inflammation, such as the following:

• CD14
• soluble CD163
• IL-6 (interleukin-6)
• TNF-1 (tumour necrosis factor receptor 1)

Analysis found that women who had a high consumption of fruit and vegetables had lower levels of inflammation. Specifically, the researchers estimated that a high intake of fruit and vegetables contributed to a significant reduction in inflammation.

Fruit and vegetables, particularly colourful ones, are rich in carotenoids, flavonoids and other compounds that have anti-inflammatory activity. Fruit and vegetables also supply fibre to the bacteria living in the intestine. These bacteria feed on the fibre and release anti-inflammatory compounds. All of this contributes to good health. The researchers argued that people who ate diets rich in fruit and vegetables may be less likely to eat unhealthy foods loaded with saturated and trans fats, sodium and sugar.

Considering other factors

The researchers had access to data on participants’ level of income and education as well as smoking and the use of different anti-HIV drugs. Therefore, they were able to take many factors into account when performing their calculations. Yet, despite considering potential factors that could have affected their results, researchers consistently found that a diet rich in fruit and vegetables was good for kidney health.

One older anti-HIV drug is a form of tenofovir called TDF (tenofovir disoproxil fumarate). Some studies have found that people with HIV who used TDF, particularly with a class of medicines called protease inhibitors, were at heightened risk for kidney injury. A safer form of tenofovir (called TAF) is now available and is commonly used.

Bear in mind

This was not a randomized clinical trial, so the study’s results are suggestive and not definitive. However, funding agencies increasingly call upon scientists to produce preliminary evidence to secure funds for larger studies. The present study’s findings on inflammation are in broad alignment with other studies, which suggest that plant-based diets are likely good for kidney health. The present study could also serve as a foundation to develop a clinical trial of dietary interventions to assess their impact on kidney health in people with HIV.

About kidney health

Eating a diet rich in fruit and vegetables is likely good for overall health. However, many issues can affect the health of the kidneys. People with the following factors are at increased risk for developing kidney disease: diabetes, high blood pressure, cardiovascular disease and having a family history of kidney failure. Advice and monitoring from a doctor to help prevent and treat underlying conditions are an important part of maintaining kidney and overall health. If necessary, additional steps can include reducing consumption of tobacco and alcohol, as well as maintaining a healthy weight.

—Sean R. Hosein

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