Effect of Caffeine Consumption on Protein Biomarkers and Cardiovascular Disease

Caffeine is one of the most widely consumed substances worldwide. This study looks to test and measure the changes in different biomarkers in the blood before and after having caffeine using capillary and venous blood sampling methods. A biomarker is a measurable indicator of biological processes. The primary goal of this clinical trial is to evaluate participant rate and adherence. It will also learn about how caffeine affects different biomarkers that may be related to cardiovascular disease. Finally, it will assess the accuracy of the capillary blood samples compared to the venous blood samples. The main questions it aims to answer are:

* What is the feasibility of recruiting and retaining participants?
* Are the study procedures appropriate to be translated to a larger future study?

Researchers will compare caffeine to a placebo (a look-alike substance that contains no drug) to see if

Participants will:

* Be randomly assigned to the control group or the caffeine group. Individuals in the control group will be taking a placebo pill with no effect and those in the caffeine group will be taking 400mg of caffeine in pill form.
* Be asked to undergo a fast of at least 8 hours overnight before taking two placebo pills or the 400 mg of caffeine via two caffeine pills. They will be required to stay fasted for 6 hours after taking the pill as well. The total time fasted will be at least 14 hours.
* Have blood collected using three different methods before taking the two pills, 3 hours after taking the pills and 6 hours after taking the pills. The 3 methods include intravenous (IV) blood sampling, finger prick and collection on Whatman 903 Protein Saver Card and collection using the TASSO+ device. The TASSO+ blood collection device is a small capillary blood collection device that is designed to be easy to use and able to be used outside of a hospital/lab setting. Whatman 903 Protein Saver Cards are special filter paper with five circles for samples, that are designed for the collection and storage of blood.

Proteomic biomarkers related to disease risk factors may shed light on the pathogenesis of different diseases. There is a knowledge gap in the effects of lifestyle interventions on the proteome, mainly because collection of blood samples by venipuncture for proteomics analysis is tedious and expensive. Discovering an at-home capillary blood collection method with samples that contain protein profiles that mirror or can be correlated to those of venous samples has the potential to greatly improve access to research studies. Cardiovascular diseases (CVD) are the most common cause of death worldwide. Caffeine is a commonly consumed substance. Many studies have shown a relationship between caffeine and reduced risk of CVD; however, the mechanisms remain mostly unknown.

The investigators are conducting a two-part feasibility study examining the effect of caffeine consumption on the relative levels of 92 cardiovascular-related protein biomarkers in samples obtained using different blood collection technologies to compare protein profiles between capillary and venous blood samples and further clarify the protective mechanisms of caffeine in mitigating CVD risk. By integrating both of these components into a single trial, the investigators aim to reduce the burden placed on participants, making the study easier and more accessible.

For the preliminary testing of the at-home blood collection methods compared with intravenous sampling, a group of 10 individuals (evenly split between male and female) will be recruited. In this phase, participants will be subject to blood collection by intravenous sampling, as well as the TASSO+ device and finger prick and collection on Whatman Protein 903 Saver Cards. After the first portion of the study is complete, data from the 10 patients will be analyzed to determine the most accurate and reliable capillary blood collection device. This sampling device will show a reasonable correlation to venipuncture, with a threshold of correlation above 70%.

For the larger at-home testing of the selected blood collection method, a group of 26 individuals will participate, again, with an even split between males and females. Participants in this second cohort will no longer have to come on premise for intravenous sampling. They can complete the entire study remotely, further reducing logistical challenges. In this phase, blood will only be collected using the capillary blood collection device that best correlates with venipuncture as validated in the first part of the study.

After the second portion of the study is complete, data from the first 10 participants will be integrated and compared with data from the second 26 participants to evaluate the effect of caffeine vs placebo on biomarkers, as well as identify any significant differences between the two cohorts.

In both phases, participants will undergo a fast of at least 8 hours prior to the administration of the caffeine or placebo. Following this fast, blood will be collected (either at home or in the lab) prior to the ingestion of the caffeine pill or placebo. Blood will also be collected at 3 and 6 hours after the ingestion of the caffeine pill or placebo. Blood samples will either be collected in the lab or collected at-home then mailed back to the lab, and stored in a -80°C freezer until proteomic analysis may be conducted to investigate the changes in biomarkers.

With this being a feasibility study, the investigators are hoping to see some results from this sample size, then translate their findings to a larger study with more participants conducted over a longer period of time in the future.

Eligibility Criteria:
Inclusion Criteria:

- Participants must be over the age of 18 to participate in the study. This is based on 400mg of caffeine being deemed safe for healthy adults.

Exclusion Criteria:

* Participants are not to be pregnant or trying to get pregnant or lactating as the recommended caffeine consumption for these individuals is less than what would be administered in this study.
* Individuals who are diabetic will be excluded from this study due to the fasting period, potentially leading to a low blood sugar state.
* Individuals with the following conditions will be excluded from the study: Hypertension or a history of hypertension Glaucoma Thyroid disease Heart disease Seizure disorder The investigators will screen the participant's medical conditions and not include anyone whose condition may interfere.
* Individuals who experience anxiety or have been diagnosed with other mental illnesses will want to consider their participation in this study. Those who experience anxiety may experience more anxiety-related symptoms with the consumption of caffeine. The investigators will screen participant's for anxiety-related disorders.
* Individuals who have recently undergone major surgery. Major surgery is any intervention that has resulted in the penetration and opening of a body cavity (i.e., chest or abdominal). Recent is within the last month.
* Individuals who are taking medication which may have adverse interactions with caffeine will be excluded from the study. The investigators will screen the participant's medications and not include anyone whose medications may interfere.