The damaging duo: Obesity and excess dietary salt contribute to hypertension and cardiovascular disease

Abstract

Hypertension is a primary risk factor for cardiovascular disease. Cardiovascular disease is the leading cause of death among adults worldwide. In this review, we focus on two of the most critical public health challenges that contribute to hypertension-obesity and excess dietary sodium from salt (i.e., sodium chloride). While the independent effects of these factors have been studied extensively, the interplay of obesity and excess salt overconsumption is not well understood. Here, we discuss both the independent and combined effects of excess obesity and dietary salt given their contributions to vascular dysfunction, autonomic cardiovascular dysregulation, kidney dysfunction, and insulin resistance. We discuss the role of ultra-processed foods-accounting for nearly 60% of energy intake in America-as a major contributor to both obesity and salt overconsumption. We highlight the influence of obesity on elevated blood pressure in the presence of a high-salt diet (i.e., salt sensitivity). Throughout the review, we highlight critical gaps in knowledge that should be filled to inform us of the prevention, management, treatment, and mitigation strategies for addressing these public health challenges.

Keywords: blood pressure; dietary sodium; hypertension; obesity.

FIGURE 1

The criterion for adults with obesity was a body mass index value above 30 kg/m² for both figure panels. (A) The prevalence of obesity in American adults rose dramatically from 1975 to 2016. (B) Data collected from 2017 to 2020 demonstrate that over 4 in 10 American adults have obesity. For both reports, an adult was defined as ≥20 years old.

FIGURE 2

Americans overconsume sodium (Quader et al. and Bailey et al.), relative to the recommendations from the American Heart Association (AHA; recommendation: <1,500 mg of sodium per day) and the Dietary Guidelines for Americans (DGA; recommendation: <2,300 mg of sodium per day) for optimal cardiovascular health.

FIGURE 3

Mechanisms of obesity affecting vascular function. eNOS, endothelial NO· synthase; NO·, nitric oxide; NOX, NADPH oxidase; O₂⁻, superoxide; ONOO⁻, peroxynitrite; ROS, reactive oxygen species; TNFα, tumor necrosis factor α.

FIGURE 4

Mechanisms of excess dietary salt affecting vascular function. ADMA, asymmetric dimethylarginine; DDAH, Dimethylarginine dimethylaminohydrolase; eNOS, endothelial NO· synthase; H₂O₂, hydrogen peroxide; NO·, nitric oxide; NOX, NADPH oxidase; O₂⁻, superoxide; ONOO⁻, peroxynitrite; ROS, reactive oxygen species; SOD, superoxide dismutase.

FIGURE 5

Republished with permissions. Dietary salt alters autonomic function by excitation of NaCl-sensing neurons in the lamina terminalis or increasing gain/excitability of bulbospinal neurons in the rostral ventrolateral medulla. Salt-sensitive hypertension is associated with increased sympathetic outflow to the splanchnic or hindlimb vasculature. A midsagittal section of the rodent brain illustrates key autonomic centers involved in salt-sensitive hypertension. (i) Neurons in the organum vasculosum of the lamina terminalis and subfornical organ sense changes in extracellular NaCl to increase sympathetic nerve activity. Potential NaCl-sensing mechanisms include an N-terminal variant of the transient receptor potential cation channel subfamily V member 1 (TRPV1), the epithelial sodium channel (ENaC), and the Nax channel. (ii) Dietary salt also increases the excitability or gain of bulbospinal sympathetic neurons of the rostral ventrolateral medulla. Thus, glutamatergic (or GABAergic) input onto RVLM neurons results in an exaggerated discharge and change in sympathetic nerve activity. BP, blood pressure; RVLM, rostral ventrolateral medulla; SNA, sympathetic nerve activity. Adapted from Servier Medical Art by Servier licensed under a Creative Commons Attribution 3.0 Unported License (https://smart.servier.com).

FIGURE 6

Mechanisms of obesity and excess dietary salt affecting kidney function and insulin sensitivity.

FIGURE 7

Sample menu for an entire day with sodium contents.

FIGURE 8

Caloric contents of popular foods in the United States. We obtained nutritional information on each company’s website in November 2022. Ice cream−peanut butter cup; 2 servings; Ben & Jerry’s^®. Pizza−XL ultimate pepperoni; 2 slices; Domino’s^®. Cheeseburger & fries−double double; In-N-Out^®. Chicken burrito−with white rice, black beans, pinto beans, guacamole, sour cream, and cheese; Chiptole^®.

FIGURE 9

Comparing caloric, sodium, and macronutrient intake between ultra-processed food and unprocessed food diets in a metabolic ward, controlled feeding trial.

FIGURE 10

Summary. A proposed positive feedback loop relation between obesity and excess dietary salt intake on risk factors (e.g., blood pressure) for CVD. CVD, cardiovascular disease.