November 2016 Issue
Dynamics of Diabetes: Prickly Pear Cactus
By Constance Brown-Riggs, MSEd, RD, CDE, CDN
Vol. 18, No. 11, P. 12
Research shows this vegetable has the power to lower
The face of diabetes is changing as the United States becomes more ethnically and culturally diverse. The US Census Bureau projects that by the year 2050 the Asian, Hispanic, and African American populations will increase 212.9%, 187.9%, and 71.3%, respectively, compared with 32.4% for the white population.
And according to the Centers for Disease Control and Prevention's National Diabetes Statistics Report, released June 2014, diabetes prevalence is significant among these groups: 13.2% in African Americans, 12.8% in Hispanics, and 9% in Asian Americans, compared with 7.6% in whites.1
Along with this changing demographic more of these groups are turning to complementary and alternative medicine (CAM) to help manage the disease. A literature review on the use of CAM among people with diabetes, published in 2007 in the Journal of Advanced Nursing, reported prevalence rates as high as 78%. And people with diabetes are 1.6 times more likely to use CAM therapies than people without diabetes.2
The use of CAM varies among ethnic groups. A 2010 article cites research showing 40% of Hispanics with diabetes used CAM compared with 20% of African Americans and 15% of whites.3 Moreover, the type of CAM use is associated with ethnic and cultural background. For example, 33% of Hispanics consume prickly pear cactus, known as nopal, as traditional Mexican medicine for treating diabetes,3 says Nimbe Torres, MSc, PhD, senior research scientist at the Salvador Zubirán National Institute of Health Sciences and Nutrition in Mexico City, Mexico.
This article discusses the use of prickly pear cactus in native Mexican diets, efficacy for diabetes management, mechanism of action, and tips for counseling patients.
What Is Prickly Pear Cactus?
Prickly pear cactus is a plant of the species Opuntia ficus indica. It's grown throughout Mexico and in many other regions, including the southwestern United States and South America.4,5 In Mexican cuisine, the pads of the plant are eaten as a vegetable. It has a light, tart flavor.6 "When cooked, the texture of nopal is similar to cooked green beans or green peppers," says Jessica Crandall, RDN, CDE, AFAA, general manager at Denver Wellness and Nutrition Center–Sodexo and a national spokesperson for the Academy of Nutrition and Dietetics. "It can also be used in soups, salads, jams, jellies, marmalade, pickles, and desserts," Crandall adds. Nopal generally is sold fresh, canned, or dried.6 In the United States, nopales—the plural form of nopal—can be found in local bodegas, farmers' markets, and some grocery stores.4
Efficacy for Diabetes Management
Nopales have long been used in traditional Mexican medicine for treating diabetes, and there's some preliminary clinical evidence to support its benefit. Single doses of nopal have been shown to decrease blood glucose levels by 17% to 46% in some patients.6
Bacardi-Gascon and colleagues conducted a study to measure the effect of nopales on postprandial glucose response in Mexican subjects with type 2 diabetes. Subjects were randomly assigned to eat one of the three test breakfast meals with and without nopales. The breakfasts consisted of chilaquiles (a casserole made with corn tortilla, vegetable oil, and pinto beans), burritos (made with eggs, vegetable oil, and pinto beans), or quesadillas (made with flour tortillas, low-fat Monterey Jack cheese, avocado, and pinto beans). The addition of 85 g nopal caused a 30% reduction in blood glucose in subjects who ate the chilaquiles, a 20% decrease in those who consumed the burritos, and a 48% reduction in patients who ate the quesadillas. The researchers suggest that this evidence provides Mexican patients with a culturally based choice for the management of diabetes.7
In November 2014, the Journal of the Academy of Nutrition and Dietetics published a study by López-Romero and colleagues that evaluated the glycemic index, insulinemic index, glucose-dependent insulinotropic peptide (GIP) index, and the glucagonlike peptide 1 (GLP-1) index, and the effect of nopal on the postprandial response of glucose, insulin, GIP, GLP-1, and antioxidant activity in patients with type 2 diabetes after consumption of a high-carbohydrate breakfast (HCB) or high-soy protein breakfast (HSPB). Study results showed that nopal has low glycemic, insulinemic, and GIP indexes and could benefit patients with type 2 diabetes. The inclusion of nopal in the HCB group had antihyperglycemic and antihyperinsulinemic effects, and in the HSPB group, it prevented postprandial blood glucose peaks. Nopal also increased the antioxidant activity in both healthy people and patients with type 2 diabetes. Consistent with previous research, this study supports the traditional use of nopal for the safe management of diabetes without any side effects.
"After the consumption of a high-carbohydrate breakfast with a high glycemic index, the addition of nopal significantly decreased the postprandial blood glucose peaks by approximately 20%. For example, if a subject with type 2 diabetes has a blood glucose concentration of 180 mg/dL after 60 minutes of consuming a high-carbohydrate breakfast, the addition of nopal can decrease blood glucose concentration to approximately 144 mg/dL," says Torres, one of the scientists involved in the study and a specialist in nutrigenomics, nutrigenetics, microbiota, and traditional Mexican foods.
Mechanism of Action and Dose
The blood glucose-lowering effect of nopal is attributed to its high fibrous polysaccharide and pectin content.8 "Nopal is a vegetable that contains different compounds such as soluble (mucilage and pectin) and insoluble fiber (hemicellulose, cellulose, and lignin), polyphenols, vitamin C, and water," Torres says. "The presence of all of these compounds makes the nopal have a low glycemic index (GI 32.5). Foods low on the glycemic index scale tend to release glucose slowly and steadily into the circulation. The slow and steady release of glucose after the consumption of nopal is helpful in keeping blood glucose under control," Torres adds.
Doses in studies for diabetes generally range from 100 to 500 g of prickly pear cactus daily, divided into three equal amounts.6 However, Torres and colleagues observed benefits when prickly pear cactus was eaten once daily before the main meal. "In our experience, we've seen that the best beneficial effect of nopal is [when] it's consumed before the main meal. We recommend consuming 300 g of raw nopal or 250 g (approximately 13/4 cups) of steamed nopal cooked no more than eight to 10 minutes, every day," Torres says.
According to the USDA National Nutrient Database for Standard Reference, Release 28, one cup (149 g) of cooked nopal provides 22 kcal, 5 g carbohydrate, 3 g fiber, and 2 g protein.
Patients must be cautious when using nopal in conjunction with antidiabetes medications, as the combination may cause hypoglycemia. Dietitians should advise patients who use nopal regularly to monitor their blood glucose closely.
As the face of diabetes continues to change and data emerge that support medicinal benefits of traditional ethnic foods, it's important for dietitians to increase their knowledge of cultural foods and eating patterns. Studies have shown that compliance with MNT is higher when cultural competence is matched between the health provider and the patient.4 Hispanic patients with diabetes should be encouraged to preserve cultural traditions and continue to include nopales in their diet.
— Constance Brown-Riggs, MSEd, RD, CDE, CDN, is a past national spokesperson for the Academy of Nutrition and Dietetics specializing in African American nutrition, and author of The African American Guide to Living Well With Diabetes and Eating Soulfully and Healthfully With Diabetes.
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