Hypertension is a prevalent cardiovascular disease in older adults. Over the past few years, hypertension has progressively grown to be a global health concern (1). From 1990–2019, the prevalence of hypertension doubled, with a total of approximately 1.2 billion adults global having hypertension, most in countries with middle or low income (2). A global blood pressure screening study found that more than a third of people have high blood pressure and approximately a half are unaware they have it (3). Since high blood pressure rarely causes symptoms on its own, it is frequently disregarded. Hypertension, as a risk factor often leads to cerebral hemorrhage, heart failure, coronary heart disease and even illness (4). Recent studies also show that high blood pressure increases the incidence of breast cancer and Parkinson's disease (5, 6). Therefore, determining the best course of action for managing high blood pressure and reducing associated consequences has taken precedence.

The pathological mechanism of hypertension presents multi-dimensional interactive characteristics, involving multi-dimensional factors such as abnormal activation of the renin-angiotensin-aldosterone system (RAAS), imbalance of immune homeostasis, metabolic regulation disorders, vascular endothelial damage and genetic susceptibility (7, 8). Previous research (9) has connected the development of hypertension to oxidative stress, and the immune system plays a core regulatory role in it (8, 10). The evidence shows that hypertensive patients present with a persistent low-grade inflammatory state (11). The synergistic effect of innate and adaptive immune responses leads to abnormal activation and infiltration of monocytes/macrophages and lymphocytes, accompanied by enrichment of proinflammatory factors and chemokines, which aggravates oxidative stress. Oxidative stress reversely promotes the release of inflammatory mediators through signaling pathways (10). The two form a cascade amplification effect, jointly driving a vicious cycle of vascular remodeling and target organ damage. Besides, Oxidative stress occurs when there is an unbalanced concentration of oxidants and antioxidants in the body, with an emphasis on oxidants (12). This imbalance can cause disruptions to redox signaling, regulation, and molecular damage (12, 13). In addition to producing reactive oxygen species (ROS) by itself, which damages and kills endothelium, oxidative stress also interacts with the body's inflammatory proteins, hastening the death of cells (14, 15). Studies have shown that reducing oxidative stress in the body improves blood vessel stiffness and improves blood pressure (16).

However, several factors have a limited effect on the total oxidant/antioxidant system. Variations in dietary composition, obesity, exercise, smoking, and other lifestyle choices impact the body's degree of oxidative stress. Thus, we selected the oxidative balance score (OBS) as a measure to quantify the effect of diverse diets and lifestyles on the entire oxidant/antioxidant system (17). OBS is a composite index of 20 distinct dietary and lifestyle elements that accentuates the overall balance of antioxidants and oxidants at the dietary level. It's acknowledged that a higher OBS indicates superior antioxidant status. Previous researches have demonstrated an adverse association between OBS and various diseases, including metabolic syndrome (18), depression (19), breast cancer (20), and type 2 diabetes (21). Here, we explored the connection between OBS and the incidence of hypertension. We investigated the potential effects of OBS on hypertension using data from the National Health and Nutrition Examination Survey (NHANES) from 2007–2018.

28,035 samples from seven NHANES cycles between 2005 and 2018 have been included in this study's analysis of the connection between OBS and hypertension. We discovered in this study that OBS was considerably higher in non-hypertension individuals than in hypertensive individuals. Additionally, a higher OBS demonstrated a negative relationship with the likelihood of developing hypertension. Upon accounting for potential influencing factors, the findings indicated that the impact of OBS on hypertension was significantly influenced by age. People under 60 were more likely to benefit from the trial and had a lower risk of developing hypertension than people over 60.

Numerous studies on animals and in humans have tied oxidative stress to the onset and development of hypertension. When the quantity of ROS surpasses the antioxidants' ability to scavenge them, oxidative stress results. In addition to directly affecting cellular macromolecules, which may result in cell damage and death (25), oxidative stress also influences inflammatory factors, which can accelerate blood vessel aging and elevate blood pressure (15). The probability of cardiovascular disease climbs with age, indicating that age is an important factor in cardiovascular disease (26). A cohort study revealed a significant link between age and hypertension, particularly hastening the onset of hypertension in middle age (27). In aged hypertensive mice, Angela Wirth et al. (28) discovered the development of accelerated endothelial cell dysfunction in conjunction with elevated ROS in the vasculature. Besides, as we age, blood vessels begin to stiffen, and when the endothelial cells in the blood vessels are attacked by oxidants or inflammatory substances, the blood vessels stiffen rapidly, increasing blood flow (29). Aged cardiomyocytes have been shown to have increased free radicals and a chronic proinflammatory state too (30). The middle intima of medium-sized arteries thickens as a result of endothelial cell failure brought on by high levels of oxidative stress and inflammation in vivo (31). The renewal rate of cardiomyocytes is highest at around 20 years of age, declining steadily thereafter to less than 0.5% per year in the elderly (32). Based on these findings, it is believed that younger patients have better vascular conditions and are more likely to benefit from antioxidants.

It has been proven that the NOX family plays a substantial part in the development of hypertension (33). The production of oxides by the NOX family during the redox process in the population is the main reason for the increase in blood pressure (34, 35). In experiments with hypertensive mice, blocking the NOX pathway with a drug led to an improvement in blood vessel function and normalization of blood pressure (36). Consequently, NOX isoforms (NOX2) may be expressed in immune cells, producing high levels of oxygen free radicals and causing damage to the vascular endothelium (37).

Several research have also verified the positive correlation between antioxidants and a decreased risk of hypertension. A retrospective study discovered that eating foods high in antioxidants, such as lycopene, α-carotene, β-carotene, lutein with zeaxanthin, and total carotenoids, reduced the incidence of high blood pressure (38). Besides, in a dietary study aimed at elderly patients with metabolic syndrome (MetS) in Korea, when patients ate foods rich in antioxidants for 4 weeks, changes in the state of oxidative stress and MetS involving hypertension, arteriosclerosis and dyslipidemia (39). Additionally, in vitro experiments conducted on mice demonstrated that resveratrol plays a role in lowering blood pressure, improving oxidative stress, and enhancing cellular endothelial function (40). Furthermore, a recent study on mice demonstrated that raising the levels of the mitochondrial deacetylase sirt3 decreased oxidative stress, prevented endothelial dysfunction and vascular inflammation, and slowed down hypertension and vascular aging (41). Patients with hypertension who received the physiological oxidant melatonin1 for that year exhibited improvements in arterial stiffness and a drop in serum TAC (a measure of oxidative stress), according to randomized controlled research (42).

According to this research, an antioxidant-rich diet and way of life are good for mental health. In addition, there was age dimorphism in these trends, with younger people seeing a higher protective impact from antioxidant diet and lifestyle choices. The results emphasize the need of maintaining a diet and way of life high in antioxidants, as they can aid in the prevention and treatment of hypertension.

This study revealed the dual value of antioxidant dietary patterns and lifestyle interventions in the management of hypertension. Data from a cohort study confirmed that higher OBS in hypertensive patients was significantly associated with reduced all-cause mortality (43). Coincidentally, a large-scale cross-sectional study conducted in China also found that a healthy lifestyle and a diet rich in antioxidants can prevent hypertension (44). These findings reinforce the pivotal role of the balance of the oxidation/antioxidant system in blood pressure regulation from an epidemiological perspective. It is worth noting that OBS, as a quantitative assessment tool, can provide individuals with a visual oxidative stress risk assessment by integrating dietary components and lifestyle parameters, thereby guiding precise nutritional counseling.

Our research advantages lie in the following aspects. First, we used seven waves of high-quality, representative data from the NHANES, which are large and multi-stage. Second, the logistic regression model was adjusted to eliminate some potential confounding factors, including demographic, socioeconomic, health and lifestyle information, to obtain more accurate results.

There are a few other restrictions on the current investigation. First, because the study is cross-sectional, it is challenging to determine a causal association between OBS and hypertension. Thus, more research with a prospective design is required to demonstrate the effectiveness of OBS. In the future, prospective study designs will be used to track the association between dynamic changes in OBS and blood pressure trajectories and to use bidirectional Mendelian methods to explore the causal relationship between OBS and hypertension. Second, it is difficult to integrate all OS-related nutrition and lifestyle exposures into OBS; flavonoids, for example, were one of the components with restricted availability. Subsequent studies need to integrate food composition databases to more accurately quantify dietary antioxidant exposure. Third, all pro-oxidants and antioxidants are assumed to have a linear correlation with oxidative stress, ignoring the threshold effects of antioxidants. Finally, the limited data did not account for the effect of hypertensive medications on hypertensive patients, making it impossible to determine whether there was a differential effect of OBS between hypertensive patients taking or not taking hypertensive medications. It is anticipated that this problem will be addressed in later clinical research.

In conclusion, our analysis suggested that there was a substantial reverse correlation among OBS and hypertension. The study revealed that higher OBS, which signifies greater antioxidant exposure compared to prooxidant exposure in diet and lifestyle, is linked to decreased likelihood of hypertension. The precise mechanism behind the association between OBS and hypertension as well as its causal link warrant further investigation.