This IRB will cover a current clinical trial (NCT04244604) that was started at Auburn University (AU IRB#19-390), the Principal Investigator's prior institution, and is supported by his NIH Career Development Award (NHLBI K01HL147998).

About nine out of ten Americans overconsume dietary salt. Compared to other racial groups, Black individuals are more prone to salt-sensitive hypertension and negative cardiovascular conditions associated with high salt intake. However, there is a critical need to determine the reasons behind and mechanisms that contribute to these racial disparities. Both acute (single meal) and chronic high-dietary sodium cause small but important increases in blood sodium concentration that are associated with altered blood pressure regulation and blood vessel dysfunction. However, racial differences in these measures have not been examined. This is important because Black individuals generally exhibit lower circulating concentrations of hormones (e.g., renin, aldosterone, angiotensin 2) that buffer changes in body sodium to regulate blood pressure, and this could make them more vulnerable to the negative effects of a high-sodium meal.

Therefore, the purpose of this study is to determine whether there are racial differences in blood pressure regulation and blood flow after a high-sodium meal. The investigators will assess blood pressure regulation, blood vessel stiffness, and the blood vessel's ability to dilate before and after a high-salt meal and a low-salt control meal (both meals are low-salt tomato soup with varied added salt). The investigators will also collect blood and urine to measure sodium and determine biochemical changes that may be contributing to racial differences in cardiovascular function.

The investigators have previously used a high-sodium saline infusion to increase blood sodium and consequently increase blood pressure in Black and White individuals. The investigators' prior data suggest that increased blood sodium concentrations result in larger blood pressure elevations for a given elevation in blood sodium levels in Black compared to White adults. In this proposal, the investigators are seeking to translate these previous findings using a single high-salt meal (up to 2500 mg of sodium; similar to a few slices of pizza or a sandwich/burger and side dish). Our primary aims are to determine if the high-sodium meal causes greater 1) blood pressure dysregulation 2) decreases in blood vessel function and 3) larger changes in blood sodium in Black compared to White individuals. Other potential questions that could be determined include aging differences or an influence of fitness. The investigators will not exclude other races/ethnicities as the project will also determine the response of other minority groups (e.g. Asian or Latine/Hispanic adults) to a high-salt meal.

Participants will report to the laboratory for four visits. At the first visit, consent for study participation will be obtained and participants will be screened for eligibility. Baseline assessments will be completed which may include fitness testing and body composition assessments. If necessary, these assessments may be completed at a second in-person visit. Participants will then report to the laboratory for two experimental visits. At each visit, participants will consume a randomly assigned meal (i.e., a soup containing either low- or high-salt) and undergo assessments prior to and 30- and 60-minutes after consumption. During the study, all participants will consume both meals, however, the order of exposure will be randomly assigned.

Inclusion Criteria:

1. Are between the ages of 19-40.
2. Have blood pressure no higher than 140/90 mmHg.
3. Have a BMI below 35 Kg/m2 (otherwise healthy)
4. Free from metabolic disease (diabetes or renal disease), pulmonary disorders (e.g., COPD, severe asthma, or cystic fibrosis), and cardiovascular disease (peripheral vascular, cardiac, or cerebrovascular).
5. Do not have any precluding medical issues that prevent participants from exercising (i.e., cardiovascular issues, or muscle/joint issues including painful arthritis) or giving blood (e.g., blood thinners).
6. Are not currently smoking, using smokeless tobacco, nor smoked within the past 12 months.

Exclusion Criteria:

1. High blood pressure - greater than 140/90 mmHg
2. Obesity (BMI > 30 kg/m2)
3. History of metabolic disease (diabetes or renal disease), pulmonary disorders (e.g., COPD, severe asthma, or cystic fibrosis), and cardiovascular disease (peripheral vascular, cardiac, or cerebrovascular)
4. Medical issues that prevent safe exercise (i.e., cardiovascular issues, or muscle/joint issues including painful arthritis)
5. Medical issues that prevent giving blood (e.g., blood thinners)
6. Currently smoking, using smokeless tobacco, or vaping (within past 12 monrths)
7. Current pregnancy

Data with all HIPAA identifiers removed may be shared in future collaborative efforts pending appropriate DMDA approvals

One year after completion of trial, indefinitely

A formal plan identifying the intended use fo the data and proper completion of a DMDA and MTA (if needed) with Auburn University and the study PI.

The experimenter will be blinded to what sodium condition the participant is in, and all data analysis will be conducted blinded to the condition as well.