Design of a Genetic Score to Predict the Response to a Dietary Intervention in Adults With Metabolic Syndrome

Metabolic syndrome (MetS) results from the interaction between genetic and environmental factors. Single nucleotide polymorphisms (SNPs) are within the genetic factors. Various SNPs influence amino acid metabolism, and therefore their plasma concentrations. For example, the presence of SNPs such as rs10211524 (SLC1A4), rs9637599 (PPM1K), rs7406661 (ASGR), rs4788815 (TAT), rs199999090, rs11548193 (BCAT2), and rs45500792 (BCKDH), among others, have been related to alterations in the plasma concentration of amino acids. High plasma concentration of amino acids, specifically of branched chain amino acids (BCAA), have a positive association with the presence of different risk factors for MetS including waist circumference, dyslipidemia, blood pressure, glucose concentration and insulin resistance (IR). Moreover, subjects with MetS have a plasma BCAA concentration of up to 34% higher than subjects without MetS.

In the other hand, dietary interventions are among the environmental factors that can prevent MetS. For example, the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) in the United States recommends a low saturated fat diet (LSFD) to reduce LDL cholesterol. Although, this recommendation has been suggested to attenuate some of the metabolic abnormalities in individuals with MetS, there is no biological marker that can identify individuals who will respond to a LSFD. Notably, the presence of SNPs could help to identify those individuals. The clinical effects exhibited by SNPs when analyzed individually are generally small. For this reason, it has been sought to evaluate the contributory effects of multiple SNPs by means of a genetic score. The construction of a genetic score could capture the complex relationship between MetS, genetics, and dietary interventions, providing us with a greater understanding of the biochemical and metabolic alterations and responses to available treatments. Furthermore, a genetic score could have a therapeutic value in predicting the response to a dietary intervention in subjects with risk factors for MetS. Predicting the response to a dietary intervention may help implement individualized diets based on the genetic predisposition and clinical characteristics of each individual, showing beneficial effects on anthropometric, clinical and biochemical markers. Likewise, implementing dietary interventions for preventive purposes for complex diseases could minimize public health expenditures.

Adults will be invited to participate through advertising distributed in the City of San Luis Potosí, Mexico. Those interested in participating will be given a short telephone interview to verify that they meet the selection criteria. Then, an appointment will be scheduled to go to the Faculty of Chemical Sciences of the Autonomous University of San Luis Potosí (UASLP). During this visit, participants will be informed of the characteristics of the study, the risks and the benefits expected after the dietary intervention. Those who accept to participate will sign the consent letter. Then a clinical a nutritional assessment will be performed. A blood sample and blood pressure will be taken by a specialist. Anthropometric and body composition measurements will be made. An history of food consumption frequency will be obtained by a nutritionist. The physical activity questionnaire will be carried out (IPAQ long version). The patient will be advised not to change the level of habitual physical activity. Participants will be then assigned a diet for two months following the indications of the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) program. The follow-up of the diet will be evaluated by telephone by a nutritionist who will carry out 24-hour reminder questionnaires randomly every 15 days to each participant. After the first visit, participants will start consuming the diet corresponding to their group. The different menus will be delivered and explained to them. A food guide will be given so that they have food exchange options. Patients will be taught to fill the feed log and will be cited in two months.

During the second visit, the investigators will collect a 24-hour dietary record, food logs and the investigators will perform a second clinical and nutritional assessment, including the determination of anthropometric measurements such as weight, waist circumference and body composition, whole blood sample and blood pressure will be taken. The physical activity questionnaire will be carried out (IPAQ long version). Finally, participants will be scheduled within fifteen days for delivery of results and to explain the actions that will be carried out at the end of the study to maintain the continuity of the treatment.

Inclusion criteria

• Adults (men and women) between the ages of 18 and 60.
• Adults mexican mestizos (parents and grandparents born in Mexico).
• Adults who can read and write.
• Adults willing/able to provide informed consent.
• Adults with obesity (BMI ≥ 30 and ≤ 39 kg / m2).
• Adults with at least one of the metabolic syndrome diagnostic criteria:

Waist circumference: men > 102 cm or women > 88 cm. Hypertriglyceridemia >150 mg/dL High fasting glucose >100 mg/dL High blood pressure ≥ 130/85 mmHg Low HDL-cholesterol: men <40 mg/dL and women < 50 mg/dL

Exclusion criteria

• Adults with any type of diabetes.
• Adults with hypertension.
• Adults with kidney disease diagnosed by a medical or with creatinine> 1.3 mg / dL for men and > 1.1 mg / dL for women and / or blood urea nitrogen (BUN)> 20 mg / dL.
• Adults with acquired diseases that produce obesity and diabetes secondarily.
• Adults who have suffered a cardiovascular event.
• Adults with weight loss > 3 kg in the last 3 months.
• Adults with any catabolic diseases such as cancer and/or AIDS.
• Gravidity status
• Adults who smoke
• Adults in treatment with any medication