Cardiometabolic Benefits of Potatoes Mediated Along the Gut-Vessel Axis in Adults With Metabolic Syndrome

This study is focused on assessing potential health benefits of daily consumption of potatoes, specifically its resistant starch content (i.e. nondigestible carbohydrate), on blood vessel and gut health function in adults with metabolic syndrome. It is expected that the daily consumption of potatoes for two weeks, within a diet that follows the Dietary Guidelines for Americans, will improve blood vessel function in association with decreasing gut permeability ("leaky gut") that results in the absorption of bacterial toxins that reside in the intestine. Outcomes will therefore support dietary recommendations for potatoes to support vascular and gastrointestinal health.

Cardiovascular disease is a major public health concern in the United States, where it accounts for 1 in 4 deaths every year. Vascular endothelial dysfunction is an early event leading to cardiovascular disease and can be caused by postprandial hyperglycemia. Cardiovascular disease is also characterized by metabolic endotoxemia. Metabolic endotoxemia describes increased circulating levels of gut-derived endotoxin (lipopolysaccharide; a bacterial product derived from Gram-negative bacteria in the intestines) that results from gut barrier dysfunction, a phenomenon that is common in metabolic syndrome. Studies in animals and humans have shown that consumption of resistant starch (a type of carbohydrate found in potatoes among other foods) can help to improve vascular and gut health. This clinical trial will therefore investigate the extent to which potatoes can improve microbiota composition, alleviate metabolic endotoxemia, and improve vascular function. It is hypothesized that 2-week daily ingestion of potatoes within a diet that meets the Dietary Guidelines for Americans will limit metabolic endotoxemia by decreasing gut barrier permeability and alleviating gut dysbiosis while separately improving vascular function by limiting postprandial hyperglycemia. This study will address the following objectives: 1) define changes in gut barrier function in association with improved gut microbiota composition, increased fecal short chain fatty acid (SCFA) production, and decreased serum endotoxin, 2) define changes in postprandial glycemic responses and endotoxemia, and 3) define changes in gut hormones that promote glycemic control and changes in markers of oxidative stress in relation to improvements in endothelial vascular function, all following 2-week potato consumption. To test the hypothesis, all participants will complete a randomized cross-over trial where they will receive a potato or bagel along with a diet that meets the Dietary Guidelines for Americans for 2 weeks. They will then undergo a 2-h postprandial study to define the influence of potato consumption on vascular function, glycemic control, and endotoxin translocation. Upon completing the intervention, participants will undergo a gut permeability test, fecal samples will be collected for microbiota composition analysis, and blood samples will be collected to assess endotoxin and inflammatory markers. Upon successfully completing this study, it is anticipated that chronic consumption of potatoes will be demonstrated to be an effective dietary strategy to reduce metabolic endotoxemia, improve gut health, and improve vascular function.

Eligibility Criteria:
Inclusion Criteria:

* Fasting glucose 100-125 mg/dL
* Waist circumference \>102 cm (men), \>88 cm (women)
* Fasting triglyceride \>150 mg/dL
* Fasting HDL cholesterol \<40 mg/dL (men), \<50 mg/dL (women)
* Non-smoker
* Non-dietary supplement user (\>1-mo)
* Free of gastrointestinal disorders, cardiovascular disease, cancer
* No recent use of antibiotics or any medications affecting glycemia, lipidemia, or blood pressure

Exclusion Criteria:

* Use of anti-inflammatory agents or probiotics
* Vegetarian, gluten-intolerant, carbohydrate-restricted diet
* Alcohol intake \>2 drinks/d
* \>7 hours/week of aerobic activity
* Women who are pregnant or lactating or have initiated or changed birth control in the past 3-months
* Taking medications that affect blood sugar, blood pressure, blood vessel health, or inflammation
* High blood pressure or any vascular diseases
* HIV, hepatitis, or blood disorders such as hemophilia
* Gastrointestinal disorders
* Cancer (current or past history)
* Anemia