Acute Effects of Watermelon on Vascular Function and Serum Lycopene

Purpose and Objectives Arterial stiffness and endothelial dysfunction are early independent predictors of cardiovascular disease (CVD), the leading cause of death for women ages 60 and older in the United States. It is well-known that age-related decreases in vascular function are partially due to increases in oxidative stress and inflammation. In attempts to combat CVD, previous studies have investigated provision of isolated food compounds in supplement form. For example, purified lycopene has been shown to decrease oxidative stress, and our previous work supports the supplemental use of glutamine and arginine powders for improving vascular endothelial function of older adults. Watermelon is among the greatest plant sources of arginine and glutamine, and it is one of the richest sources of lycopene. However, clinical studies evaluating the whole food have not been done.

According to the Healthy Eating Index, only 27% of women ages 60 and older meet the daily dietary recommendations for 2.5 fruit servings. Likewise, although no Recommended Dietary Allowance for lycopene exists, this age group consumes less lycopene daily than is provided in one serving of watermelon. While reasons for poor fruit intake among older adults are multifactorial, difficulty chewing and inability to prepare fresh foods in the home environment have been noted as significant barriers to fresh fruit and vegetable intake. Of note, a previous systematic review suggests that 100% fruit and vegetable juices may be practical vehicles for improving intake of antioxidant nutrients among older adults. The provision of 100% watermelon juice to older adult women represents a practical, innovative approach to increase consumption of a food containing multiple components that may act in synergy to improve vascular function. Therefore, the purpose of this study is to investigate the effects of a one-time serving of 100% watermelon juice on blood vessel function and serum lycopene.

Specific Aims

The specific aims of this study are to:

• To determine whether consumption of a 12-ounce serving of 100% watermelon juice by non-obese women ages 60-75 will result in increased levels of serum lycopene.

Hypotheses: Acute supplementation with 100% watermelon juice will result in increased serum lycopene.

• To determine whether consumption of a 12-ounce serving of 100% watermelon juice by non-obese women ages 60-75 will result in improved vascular endothelial function as assessed by flow-mediated dilation (FMD) and decreased arterial stiffness as assessed by pulse wave analysis (PWA).

Hypotheses: Acute supplementation with 100% watermelon juice will result in improved vascular endothelial function and decreased arterial stiffness.

Inclusion criteria

• Body mass index 18.5 - 29.9 kg/m2 (non-obese)
• Ambulatory
• Postmenopausal female
• Ages 65-70 years

Exclusion criteria

• Food allergy to watermelon
• Diagnosis of phenylketonuria
• History of hypotension, chronic uncontrolled hypertension, chronic kidney disease, diabetes, previous cardiac events or procedures,
• Smoking or other tobacco use
• Use of anticoagulant medications, cholesterol-lowering medications, vasodilatory dietary supplements (garlic, fish oil), or dietary supplements containing lycopene, ascorbic acid, L-glutamine, L-arginine, or L-citrulline
• Weight change > 10% in the previous six months