Table 1 Eligibility criteria for the effects of probiotic or synbiotic supplementation on metabolic syndrome indices

Inclusion criteria:

Population: men and women 35–75 years old

Prediabetic [FBG = 100–125 OR 2hBS = 140–199 (via OGTT)]

Informed consent

Exclusion criteria:

Current smokers, suspected or definite history of alcohol or drug abuse history

Antibiotic use in the past 3 months or during the treatment period

Using probiotic, prebiotic or symbiotic during the past 3 months

Noncompliance in consumption of the supplements

Being pregnant

Having gastrointestinal diseases, i.e., food allergies, celiac, irritable bowel disease,

severe liver, kidney, heart, nervous system diseases

Allergy to studied agents

Currently taking prescribed nonsteroidal anti-inflammatory drugs, antipsychotics, nicotinic acid