Dietary intervention for blood pressure control: a call for action!

Abstract

Observational studies have shown the relation between blood pressure (BP) and several nutrients, including protein, fiber, potassium, magnesium, and calcium. However, randomized intervention trials of individual nutrient supplements often have shown an inconsistent or only a small effect on BP. When 2 of these nutrients are consumed naturally together in foods at the recommended levels such as in vegetarian diets or in the Dietary Approaches to Stop Hypertension (DASH) dietary pattern, their BP effects are more evident and consistent (1). In this issue of the Journal, Lee et al (2) report results of a study that is consistent with the food-based research on diet and BP. Previous studies examining the effect of dietary fiber and protein separately on BP have frequently shown a positive but small effect (3). The study conducted by Lee et al not only supports the BP-lowering effect of increasing protein and fiber intake but also the possibility that nutrients consumed together in natural foods may be more effective than nutrient supplements and may have a synergistic or an additive effect.In their study, Lee et al examined the effects of lupin kernel flour, which is rich in protein and fiber, on BP among 74 overweight or obese adults. The authors replaced 40% of wheat flour in bread with flour made from a grain legume, lupin kernel. Participants were randomly assigned to consume '15-20% daily energy as either regular white bread or bread with lupin kernel flour for 16 wk; all other aspects of their diets remained unchanged. At the end of the study, participants in the lupin bread group had their 24-h systolic BP (SBP) lowered by 3.0 mm Hg (P ¼ 0.03) and pulse pressure lowered by 3.5 mm Hg (P , 0.001). The BP-lowering effect seemed to be greater among those who had above-optimal BP than among those with optimal BP at baseline.It should be noted that the dietary habits of the population in the study by Lee et al seemed to differ from that of the typical American. Indeed, except for total and saturated fats, dietary intakes of these participants at baseline were relatively close to that recommended by the DASH dietary pattern in protein, fiber, potassium, magnesium, and calcium. It is possible that this may have contributed to the moderate BP-lowering effect observed. This observation is consistent with the OmniHeart Study, which showed that a modified DASH diet containing an even greater amount of protein (25% compared with 18% energy in the DASH diet) lowered BP even further (4). Even though the substitution of the lupin kernel flour mainly resulted in increases of dietary protein and fiber, it is possible that other nutrient components not measured may also have changed and thus contributed to the BP effect. Lee et al did not suggest that the source of protein was a factor in explaining the BP effect. However, the increased protein was from a plant source, and a recent study suggested that plant protein may contribute to BP lowering, whereas animal protein does not (5). Future studies should be conducted to apply t...

Chemical composition, angiotensin‐converting enzyme‐inhibitory activity and antioxidant activities of few‐flower wild rice (Zizania latifolia Turcz.)

“…Several large epidemiological studies have indicated that there is an inverse relationship between dietary cereal fibre intake and risk of cardiovascular diseases 25. Furthermore, results from clinical trials have shown that higher intake of fibre can reduce blood pressure and total and low‐density lipoprotein cholesterol levels 8, 26. Without doubt, the high dietary fibre content of few‐flower wild rice could make it ready source of nutraceuticals or functional foods.…”

“…Based on a pooled analysis of available national and regional data, Kearney et al 7 reported the overall prevalence of hypertension in 2000 to be 26.4% of the world's population and also predicted that the burden of hypertension would increase by 60% to approximately 1.56 billion in the year 2025. Previous studies have shown a relationship between blood pressure and several nutrients, including proteins, fibre, potassium, magnesium and calcium 8. Therefore, to obtain a broad understanding of their functional health benefits and nutritional value, it is necessary to conduct a comprehensive analysis of the nutritient compositions of the leaf sheaths and stems of few‐flower wild rice.…”