Abstract
Purpose of Review
Hypertension results in significant morbidity, mortality, and healthcare expenditures. Fortunately, it is largely preventable and treatable by implementing dietary interventions, though these remain underutilized. Here, we aim to explore the role of healthy dietary patterns in hypertension management and describe approaches for busy clinicians to address nutrition effectively and efficiently with patients.
Recent Findings
DASH, Mediterranean, vegetarian, and vegan diets that include minimally processed, plant-based foods as core elements have consistently shown positive effects on hypertension. Recommendations that distill the most healthful components of these diets can significantly impact patient outcomes. Clinicians can harness evidence-based dietary assessment and counseling tools to implement and support behavioral changes, even during brief office visits.
Summary
Healthful plant-based dietary patterns can often effectively prevent and treat hypertension. Clinicians may help improve patient outcomes by discussing evidence-based nutrition with their patients. Future work to promote infrastructural change that supports incorporating evidence-based nutrition into medical education, clinical care, and society at large can support these efforts.
Supplementary Information
The online version contains supplementary material available at 10.1007/s11886-023-02008-z.
Introduction
Hypertension (HTN) is the leading modifiable risk factor for premature cardiovascular disease (CVD), increasing the risk of coronary artery disease, arrhythmias, stroke, renal failure, and mortality [1–5]. It is increasingly common, affecting up to 45% (103–115 million) of US adults [6] and 31% (1.4 billion) of adults globally [7]. Even those who do not develop HTN by 45 have a lifetime risk of 80% to over 90% for developing HTN [8]. Only 40% of American adults with HTN are well-controlled, leaving tens of millions at risk [9]. HTN also accounts for $131 billion of healthcare costs, resulting in an additional $2000 of individual healthcare expenditure annually compared to those without HTN [10]. With increasing prevalence, complications, cost, and continued suboptimal control, further action to address HTN is imperative.
Guidelines from major medical organizations continue to recommend lifestyle modification, with diet as a primary component, as the first-line therapy for HTN [8, 11–13]. More specifically, minimally processed or whole-food, plant-based (WFPB) diets effectively prevent and treat HTN, along with many other cardiometabolic comorbidities [14]. Evidence-based nutrition interventions are under-taught in medical schools globally [15]. While physicians report insufficient training and knowledge regarding nutrition [16], patients view them as having nutrition expertise [17].
This paper aims to help address the gap between evidence-based therapeutic approaches, patient expectations, and clinician knowledge. It is not meant to be a complete literature review, as an in-depth review has been previously published [18••]. Rather, it should function as a primer for busy clinicians, providing clinically relevant information to improve the delivery of evidence-based, patient-centered dietary interventions to comprehensively address HTN.
First, we will review HTN-related clinical outcomes for WFPB diets and the proposed mechanistic evidence for their effectiveness. Then, we will describe dietary recommendations for patients with HTN and explain why and how clinicians should discuss nutrition with their patients, ways to overcome common barriers to adherence, and how to incorporate nutrition assessment and counseling into the workflow of busy clinical practice. Finally, we will explore future directions clinicians can take to promote a system that prioritizes ethical care of patients using the most effective treatment modalities.
While this paper focuses on nutrition, several other important lifestyle factors impact chronic disease, including HTN and CVD. The American College of Lifestyle Medicine (ACLM) describes six pillars of health. In addition to healthful eating, they include physical activity, restorative sleep, stress management, social connection, and avoiding the use of harmful substances [19].
Evidence-Based Dietary Patterns
Various dietary patterns have been described to reduce systolic blood pressure (SBP) and diastolic blood pressure (DBP). Current recommendations by the American Heart Association (AHA) include an eating pattern that emphasizes fruits, vegetables, whole grains, predominantly plant-based proteins (legumes and nuts), fish, and seafood [13]. For those who choose to still consume meat or poultry, they advise selecting lean cuts and avoiding processed forms. Recommendations also include avoiding ultra-processed foods, which contain added salt, sugars, or fats, and artificial colors, flavorings, and preservatives.
Several dietary patterns have been evaluated for their consistency with AHA dietary guidance. The DASH, Mediterranean, pescetarian, and vegetarian (ovo, lacto, ovo/lacto) have been characterized as tier 1 dietary patterns, those with scores > 85 for alignment with the 2021 AHA Dietary Guidance [20•]. Tier 2 patterns score from 75 to 85 for alignment with 2021 AHA Dietary Guidance and include vegan and low-fat diets [20•]. Recent systematic reviews note that plant-based dietary patterns result in superior HTN, and cardiovascular-related health outcomes compared to animal-based diets [21, 22]. As this paper will outline, optimizing the quality of plant-based dietary patterns has the potential to immensely impact the prevention and treatment of HTN [23].
DASH Diet
The Dietary Approach to Stop Hypertension (DASH) diet is one of the most effective dietary patterns for preventing and treating HTN [24, 25]. It emphasizes fruits, vegetables, and low-fat dairy foods; includes whole grains, poultry, fish, and nuts; and minimizes fats, red meat, sweets, added sodium, and sugar-containing beverages [26]. Interestingly, the initial premise of the DASH diet was to “have the blood pressure-lowering benefits of a vegetarian diet, yet contain enough animal products to make it palatable to nonvegetarians,” after earlier studies showed those consuming vegetarian diets had the lowest blood pressures in industrialized societies [27].
Recent systematic reviews and meta-analyses demonstrate the impact of DASH diets on the prevention and treatment of HTN [28, 29]. Those with the highest, compared to the lowest, adherence to the DASH diet resulted in a 20% decreased risk of developing HTN [28]. Additionally, compared to a control diet, the DASH diet significantly reduces SBP by 3.2 mm Hg and DBP by 2.5 mm Hg regardless of HTN diagnosis [29]. Individual clinical trials are even more impressive, with mean SBP reductions from 5.3 to 20.8 mm Hg for those with SBP < 130 and ≥ 150 mm Hg, respectively [30].
Mediterranean Diet
A Mediterranean diet (MedDiet) represents commonalities of diets in Mediterranean countries [31]. It consists of high consumption (every meal) of fruits, vegetables, whole grains, nuts, and legumes; moderate consumption (daily to weekly) of fish, poultry, and dairy products; limited intake (less than twice weekly) of red meat and sweets; and red wine “in moderation” [32]. The MedDiet also emphasizes using unsaturated fats, mainly olive oil, as the primary source of added fat. Two recent meta-analyses exploring the relationship between MedDiet and HTN specifically noted small but significant average reductions in SBP (1.44–1.5 mm Hg) and DBP (0.7–0.9 mm Hg), with greater reductions achieved in those with higher baseline SBP [33, 34].
Further analysis of the MedDiet shows its main benefit is from low meat consumption and high intake of vegetables, fruits, nuts, and legumes, with no additional benefit from the consumption of fish and dairy [35]. Additionally, while the Mediterranean diet includes moderate wine consumption, recent evidence suggests that no amount of alcohol can be deemed unequivocally beneficial for HTN and overall health [36]. We note that the healthful effects traditionally attributed to wine may instead reflect those of other lifestyle factors, such as social connection.
Vegetarian and Vegan Diets
Lacto-ovo vegetarian diets exclude all animal flesh—meat, game, poultry, fish, and shellfish—but include dairy and eggs, while vegan diets exclude all animal products. Large cross-sectional studies have demonstrated an inverse relationship between the restriction of animal products and both age-adjusted HTN prevalence and blood pressure readings, with vegans having the lowest, omnivores having the highest, and vegetarians and pescatarians in between [37–39]. Meta-analysis data demonstrated that vegetarian dietary patterns reduced SBP by 4.8–6.9 mm Hg and DBP by 2.2–4.7 mm Hg compared to omnivorous diets [40]. More recent meta-analysis data suggest that while non-calorically restricted vegan diets do not outperform non-vegan diets in all-comers, they do among those with elevated SBP above 130 mm Hg, resulting in an average decrease in SBP and DBP of 4.10 mm Hg and 4.01 mm Hg, respectively [41].
While more healthful plant-based diets decrease HTN risk, vegan and vegetarian diets in which unhealthy, highly processed plant-based foods predominate can increase the risk of HTN [42]. This highlights the importance of not only limiting animal-based dietary components but also ensuring the high nutritional quality of included plant foods.
Whole-Food, Plant-Based (WFPB) Diet
The dietary patterns above are associated with beneficial outcomes, largely due to their common factors, including minimally processed, plant-based foods while limiting processed foods and animal products. A whole-food, plant-based (WFPB) diet is a rigorous variation on these shared healthful components, maximizing consumption of minimally processed, plant-based foods and minimizing or excluding all processed foods and animal products, including red meat, processed meat, poultry, fish, eggs, and dairy products [43]. The individual whole, plant-based food groups—fruits and vegetables [44], legumes [45], whole grains [46], nuts and seeds [47], and herbs and spices [48]—have each been shown to improve HTN-related outcomes.
Mechanistic Evidence
A balanced WFPB diet exerts its blood-pressure-lowering effect through several mechanisms, including promoting weight loss, minimizing sodium, containing adequate levels of health-promoting micronutrients and phytonutrients, and avoiding harmful components of animal foods [18••].
Weight Loss
Higher BMI is linked to a higher incidence of HTN, and weight loss often improves blood pressure [49, 50]. In fact, in some studies, BMI accounts for up to 50% of the blood pressure variations between diet groups [37]. WFPB diets have been shown to effectively promote weight loss and improve HTN [51].
Sodium and Potassium
Sodium consumption is a significant risk factor for HTN [52], responsible for up to 9–17% of the population attributable risk [53]. Sodium-restricted diets, such as the DASH and WFPB diets, stress the avoidance of highly processed foods, the predominant source of dietary sodium in the USA [54], and have been shown to decrease blood pressure in large meta-analyses [55].
Potassium has been shown to reduce blood pressure by improving vasodilation, reducing vascular tension, and promoting natriuresis [56–58]. The most concentrated sources of potassium include legumes, fruits, and starchy and non-starchy vegetables.
The sodium-potassium-ratio is a stronger risk factor for HTN, CVD, and mortality than either element alone [59–61]. As most Americans both overconsume sodium [62] and underconsume potassium [63], dietary patterns for patients with HTN should aim to correct this imbalance.
Magnesium and Calcium
Magnesium intake is inversely related to blood pressure and can help prevent and treat HTN by promoting healthy endothelial function and vasodilation [64, 65]. Magnesium is concentrated in leafy greens, legumes, seeds, nuts, whole grains, and other high-fiber foods.
While low calcium intake promotes vasoconstriction and increased peripheral vascular resistance [66, 67], sufficient intake appears beneficial for preventing and treating HTN [68, 69]. Though often associated with dairy in Western cultures, there are many excellent plant sources of calcium, including low-oxalate green leafy vegetables, tofu, legumes, nuts, seeds, and nondairy milks.
Fiber, Naturally Occurring Nitrates and Phytonutrients
Only 5% of US adults meet daily recommendations for fiber [70]. Fiber reduces the risk of HTN and has been shown to reduce BP independently of its effect on weight loss in a meta-analysis of clinical trials [71, 72]. High-fiber plant-based diets may also beneficially affect the gut microbiome composition [73], which may help regulate blood pressure [74]. Dietary fiber is plentiful in whole plant foods but is not naturally present in animal products.
Nitrate-rich leafy green vegetables reduce inflammation and enhance nitric oxide production, which relaxes vascular smooth muscle and thereby lowers blood pressure [75, 76]. Beetroot juice has also been shown to reduce blood pressure among patients with HTN in several systematic reviews through nitrate-dependent and independent mechanisms [77–79]. However, due to high oxalate content, significant beet consumption may not be advisable for patients prone to nephrolithiasis [80]. In contrast to naturally occurring nitrates, synthetic nitrates and nitrites used to preserve processed meats are linked to the production of nitrosamines, which are known carcinogens and may also contribute to higher blood pressure [81, 82].
Phytonutrients, such as polyphenols and plant sterols, can help to control HTN via antioxidant, anti-inflammatory, vasodilatory, and apoptosis-inducing pathways [83–85]. The most concentrated sources are colorful whole-plant foods such as vegetables, fruits, legumes, whole grains, nuts, seeds, herbs, spices, and teas.
Animal Food Components
Diets higher in animal foods tend to be associated with a greater risk of HTN [38, 39, 86–88]. They contain higher levels of saturated fat [89, 90] and advanced glycation end products (AGEs) [91] and promote the formation of trimethylamine-N-oxide (TMAO) [92], which have all been linked to HTN and CVD. A more comprehensive review of the health harms of animal food consumption can be found elsewhere [93•].
Dietary Recommendations for HTN
While consuming adequate amounts of specific key nutrients is important for individuals with HTN, the most effective way to address HTN is with an overall health-promoting dietary pattern, as in Table 1. These recommendations are illustrated in a 3-day sample menu, as shown in Fig. 1. The foods included are healthy sources of macronutrients and rich sources of dietary fiber and micronutrients that promote vascular health. Additionally, though beyond the scope of this article, such plant-based dietary patterns can powerfully affect cardiovascular and metabolic health beyond HTN alone [94].