Composite dietary antioxidant index and the risk of heart failure: A cross‐sectional study from NHANES

Abstract Background Previous studies show that oxidative stress is important in heart failure (HF) pathogenesis. The composite dietary antioxidant index (CDAI), which reflects the antioxidant profile of nutrient supplements, is associated with cardiovascular mortality risk. However, the association between CDAI and the risk of HF remains unknown. Hypothesis In this study, we investigated the relationship between CDAI and HF risk using National Health and Nutritional Examination Survey (NHANES) data. Methods The data of participants aged >40 years old from the NHNANES between 2001 and 2018 were obtained and used to assess the relationship between CDAI and the risk of HF. Logistic regression was used to calculate the odds ratio (OR) of CDAI for the risk of HF. Results A total of 29 101 participants were divided into the HF (n = 1419; 4.88%) and non‐HF groups (n = 27 682; 95.12%), HF group participants had lower CDAI than the non‐HF group (−0.32 ± 0.14 vs. 0.67 ± 0.05, p < .0001). Compared with the lowest CDAI quartile (Q1), the OR for HF risk was 0.88 (0.68−1.13) for Q2 (p = .30), 0.77 (0.61−0.99) for Q3 (p = .04), and 0.68 (0.52−0.89) for Q4 (p = .01). Conclusions CDAI was negatively associated with the risk of HF. Our findings show that the intake of an antioxidant‐rich dietary is a potential method to reduce the risk of HF.

Heart failure (HF) affects nearly 6.5 million adults in the United States, and the number of HF cases keeps increasing because of the growing and aging population. 1,2Increasing evidence has revealed that dietary supplementation patterns are associated with HF progression.Dietary supplementation patterns, such as sodium and fluid restriction, low dietary inflammatory patterns, and Mediterranean dietary patterns can reduce the risk of HF. 3,4 It is well recognized that oxidative stress is involved in the progression of HF and that the diet-related oxidative stress should not be neglected in cardiovascular diseases. 5,6e composite dietary antioxidant index (CDAI) is a score reflecting the antioxidant profile of nutrient supplements.8][9] A previous study has shown that a high CDAI is linked to a low cardiovascular mortality risk. 10However, the effects of combined dietary antioxidants on the risk of HF remains unknown.
Therefore, this study aimed to investigate the relationship between CDAI and HF risk using National Health and Nutritional Examination Survey (NHANES) data.

| Study population
We obtained data from the NHANES conducted between 2001 and 2018.NHANES was a cross-sectional survey to evaluate the health and nutritional status of the noninstitutionalized US population.This survey collected information on the nutritional and health statuses of American families through questionnaires survey and laboratory examinations.Details are available at https://www.cdc.gov/nchs/nhanes/about_nhanes.htm.This cross-sectional study collected the data of patients aged >40 years old from the NHANES.We used the "MCQ160B" variable in the questionnaire to diagnose HF, which asked if a doctor had ever diagnosed the patient with congestive HF.We selected 29 107 of the 50 042  The calculation of CDAI was based on the concentration of antioxidant components in foods and the antioxidant capacity weight of each component.The total score for each food was the weighted average of all the antioxidant component scores in that food.Then, the CDAI for each participant was the weighted average of the total antioxidant capacity (TAC) scores for all food consumptions.
Diagnosing of the following covariables was based on a questionnaire or laboratory examination data.Hypertension was diagnosed when a participant was told by a doctor or when they had a blood pressure >140/90 mmHg, or a history of taking antihypertensive drugs.Metabolic syndrome (MetS) was diagnosed based on clinical judgment and required at least three of the following criteria to be met: waist circumference, blood pressure, blood glucose, triglycerides (TG), and HDL cholesterol levels. 14The specific criteria for each of these factors may vary according to sex and ethnicity, and physicians should consult the most recent guidelines and studies when making a diagnosis.Abbreviations: CDAI, composite dietary antioxidants index; CI, confidence interval; CKD, chronic kidney disease; MetS, metabolic syndrome; OR, odds ratio.
To our knowledge, this is the first population-based retrospective cohort study to explore the relationship between CDAI and HF risk.
We found that CDAI had a negatively relationship with the risk of HF after adjusting for potential confounders, and people in the higher quartiles of the CDAI score had a reduced the risk of HF compared to those in the lowest quartile of CDAI.
Oxidative stress, one of the most important factors in cell injury, play an important role in the pathogenesis of HF. 5 Because nutritional supplements play an important role as antioxidants, the focus on the effects of dietary TAC is increasing.Dietary TAC is calculated from the oxygen-free radiation absorption capacity, and it is associated with a lower risk of HF. 17 Dietary intakes can regulate the plasma redox and protect from reactive oxygen species.
Therefore, high dietary antioxidants may reduce the risk of HF. 18 The CDAI comprises vitamins (A, C, and E) and nutritional factors (zinc and selenium), as a score of total dietary antioxidants, and is widely used in the clinical situations.High CDAI is a protective factor against depression, 11 and higher CDAI has been linked to decreased T A B L E 3 Unadjusted and adjusted model for the association between CDAI and the risk of HF. cardiovascular mortality risk. 10Vitamin C supplementation increased myocardial contractility and endothelial function. 19Vitamin E can also increase endogenous antioxidant levels.In patients with HF, vitamin E supplementation can reduce the risk of developing HF. 20

| CONCLUSION
In our study, CDAI, a score reflecting the dietary profile of antioxidants, was negatively associated with the risk of HF.Dietary intervention may be an easily modified method to reduce the risk of HF, and further studies involving the underlying mechanisms are needed.

| Study limitation
This study had several limitations.First, this was an observational study.Second, the diagnosis of HF was made through a questionnaire survey, making it difficult to assess the severity of HF.In addition, the data on ejection fraction, a subtype of HF, were missing.
participants aged over 40 years old after excluding those with missing CDAI data.The survey was approved by the National Center for Health Statistics Ethical Review Board, and all participants provided informed consent.Researchers can access the database without applying. 11F I G U R E 1 Flow chart of study participants.Sample selection and exclusion criteria for the comparison of HF and non-HF participants.CDAI, composite dietary antioxidants index; CKD, chronic kidney disease; HF, heart failure; NHANES, national health and nutritional examination survey.

Hyperlipidemia 15 was
diagnosed using two methods: first, a history of lipid-lowering drug use; and second and detecting elevated levels of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), or TG in untreated patients.Specifically, hyperlipidemia was diagnosed when the serum TC exceeded 5.2 mmol/L, LDL-C exceeded 3.4 mmol/L, or TG exceeded 1.7 mmol/L.Chronic kidney disease (CKD) was identified by either an estimated glomerular filtration rate <60 mL/min/1.73m 2 or a urine albumin−creatinine ratio >30.
12A B L E 1 Characteristics of participants from HF and non-HF group.Each participants' food and nutrient intake in the NHANES was collected from the dietary interview component, which called "what we eat in America."Thedata analysis was conducted by the Food Surveys Research Group of the US Department of Agriculture.The participants responded to two recall surveys, the first time was in the Mobile Examination Center, while the second was on the telephone.weused the first recall data to avoid memory drift caused by too long a time.Based on the interview, we determined the intake of dietary supplements, including dosage, frequency, and duration of consumption.CDAI is based on the dietary intake of six antioxidants: zinc, selenium, carotenoids, vitamins A, C, and E.12 Abbreviations: CDAI, composite dietary antioxidants index; CKD, chronic kidney disease; HF, heart failure; MetS, metabolic syndrome.2.2 | Calculation of CDAI 16 Weighted associations between the CDAI and the risk of HF in the multivariable.
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