Effects of Nopales (Opuntia Spp.) on Lipoprotein Profile and Oxidative Stress in Moderately Hypercholesterolemic Adults

In light of the high cardiovascular disease morbidity and mortality, promoting simple interventions to improve serum lipids and decrease oxidative stress are warranted to help prevent chronic diseases. Commonly prescribed dietary interventions for cardiovascular disease risk reduction include the use of functional foods known to have beneficial effects on risk factors.

Because of their fiber content, nopales (prickly pear cactus pads from the Opuntia species) are commonly regarded among Mexicans as a medicinal plant for glycemic and cholesterol control. However, the literature documenting their purported hypocholesterolemic potential is scarce. Most studies have focused on the prickly pear fruit, rather than the actual nopales cactus pads. Given the unique composition and potential benefits of nopales, their use may be an ideal approach as an adjunct therapy for the reduction in cardiometabolic risk factors.

The aim of this study is to evaluate the efficacy of a 2-week intervention with nopales pads for the reduction of established CVD risk factors (serum lipids) in comparison to a control food with lower antioxidant and fiber content (cucumber) among adults with moderate hypercholesterolemia in a randomized controlled crossover trial. Because limited data exists on the effects of nopales supplementation on other factors associated with cardiometabolic risk, an exploratory assessment of how biomarkers of insulin sensitivity, inflammation (high sensitivity C-reactive protein [hsCRP]) and oxidative stress (LDL oxidizability and total antioxidant capacity) will also be conducted.

In this randomized crossover trial, healthy adults with moderate hypercholesterolemia (LDL-cholesterol ≥ 120 mg/dL) but otherwise healthy will be randomly assigned to supplementation with 2 cups/day of nopales (300 g; intervention) or cucumbers (208 g; control), divided into two 1 cup daily doses with each of two main meals. After a 3-week washout period, each group will receive the alternative treatment for an additional 2 weeks. Participants will be asked to refrain from making any additional changes to their usual diet throughout the duration of the entire study.

Fasting blood samples will be collected at the beginning and end of each dietary intervention. At the beginning and end of each dietary intervention an additional fasting blood sample will be collected at least one day apart from the main blood collection day for measurement of serum lipids to account for day-to-day variability. Outcome measures include a complete lipid panel (total cholesterol, HDL-c, LDL-c, and triglycerides), fasting glucose, insulin, oxidized LDL and LDL susceptibility to oxidation, total antioxidant capacity (TAC), and vitamin C.

Inclusion criteria

• Moderate hypercholesterolemia (LDL cholesterol ≥ 120 mg/dL)

Exclusion criteria

• Use of hypolipidemic medications
• Regular physical activity (≥ 30 min /day for ≥ 5 days/week)
• Presence of known chronic diseases (e.g., diabetes, CVD, cancer, hepatitis, inflammatory conditions, gastrointestinal disorders)
• Consumption of > 4 servings/day of fruits and vegetables
• Following a restrictive diet (e.g., carbohydrate restriction, veganism) or having any condition likely to require specialized dietary modifications
• Use of supplements (antioxidants, fiber and botanicals)
• Latex allergy
• Fear of needles
• Breastfeeding, pregnancy, or intent to become pregnant
• Unwillingness to comply with study protocol
• Participation in other research studies.