Taylor, E. N. et al. DASH-style diet associates with reduced risk for kidney stones. J.Am. Soc. Nephrol. doi:10.1681/ASN.2009030276

Forman, J. P. et al. Diet and lifestyle risk factors associated with incident hypertension in women. JAMA 302, 401–411 (2009).

Diet and lifestyle choice can reduce the risk of hypertension and kidney stones, according to two prospective, observational studies. In one study, individuals who consumed a diet high in fruit and vegetables, moderate in low-fat dairy products, and low in animal protein, had a reduced risk of developing kidney stones. In the other study, women who adhered to low-risk dietary and lifestyle factors had a reduced risk of developing high blood pressure. John Forman of the latter study group says that the relevance of his group's findings are clear, “...the take-home message is that individuals and society have the power and responsibility, by modifying diet, lifestyle, and behaviors, to hypothetically prevent the development of hypertension—a disease that takes a staggering toll on public health”.

In their study, Forman and colleagues quantified the extent to which the risk of developing hypertension could be lowered in women by following a lifestyle that only exposed them to low-risk factors. The researchers also aimed to predict the percentage of hypertension cases in women that could potentially be prevented by adherence to these low-risk dietary and lifestyle factors. The study included nearly 84,000 women aged 27–44 years from the second Nurses' Health Study (NHS II) who had normal blood pressure at the study's initiation. Forman and colleagues followed the women for 14 years and determined whether or not they developed hypertension during this time. “We found that women who followed six low-risk factors, namely maintaining a normal weight, eating a healthy diet, exercising an average of 30 min daily, drinking alcohol in moderation, avoiding nonprescription pain relievers, and taking at least 400 mg of folic acid daily, had a nearly 80% reduction in their risk of developing hypertension compared with women who did not follow all of these low-risk factors”, states Forman.

Approximately three-quarters of US women will develop hypertension, which is the most important contributor to death in women. Although many previous studies have examined whether adherence to a particular dietary regimen or lifestyle factor can lower the risk of hypertension, Forman et al. say that theirs is the first to determine the proportion of new-onset cases of hypertension that could conceivably be prevented by modification of lifestyle. As Forman explains, “...hypothetically, if all women had followed these six low-risk factors, then 78% of all cases of high blood pressure may have been avoided”.

The researchers also found that adherence to the low-risk factors lowered the chances of developing hypertension to a similar extent regardless of family history of hypertension. “This finding means that even if a woman has a parent with high blood pressure, adherence to a healthy lifestyle could potentially prevent the development of hypertension” says Forman.

In another study, Eric Taylor and colleagues investigated the effect of diet on the development of kidney stones. Previously, the researchers had identified associations between individual dietary factors and risk of kidney stone formation. These findings led to the initiation of a study to investigate the effect of dietary patterns, rather than individual dietary factors, on risk of stone formation. Taylor and colleagues assessed the individual diets of nearly 240,000 participants in three large cohorts: the Health Professionals Follow-Up Study, the NHS I and the NHS II. The researchers then constructed a Dietary Approaches to Stop Hypertension (DASH) score that increased on the basis of eight different dietary components: high intake of fruit, vegetables, nuts and legumes, low-fat dairy products, and whole grains and low intake of sodium, sweetened beverages, and red and processed meats. Over a combined follow-up of 50 years, the researchers identified 5,645 new cases of kidney stones. As Taylor explains, “...despite higher levels of dietary oxalate, participants with higher DASH scores had a 40–45% lower risk of kidney stone formation than did participants with lower DASH scores”. On the basis of their findings, the researchers propose that a DASH-style diet may represent a novel means of preventing the formation of kidney stones.

Taylor says that more work is needed to define the effect of a DASH diet on urine composition, to determine the mechanism by which this diet reduces the risk of kidney stones. He is also in favor of a randomized, controlled trial, to determine the efficacy of a DASH-style diet compared with medical intervention for the prevention of calcium kidney stones.