Nowadays, food is perceived not only as a source of energy and macronutrients, but also as a regulating health factor. Due to the demand for healthy substitute of standard meal products, the range of functional foods is constantly expanding. One of the most common types of substitutes are biscuits enriched with bioactive ingredients, with reduced fat and sugar content, or made with the use of gluten-free flours. These features are desirable from the perspective of influencing on metabolic reactions of the body, leading to inflammation and, consequently, obesity, dyslipidaemia, insulin resistance and hypertension, which are components of the metabolic syndrome (MS). Considering designing functional food, polyphenols are noteworthy due to their properties, such as antioxidant and anti-inflammatory effects. A rich source of these bioactive compounds is St. John’s Wort, which was used to enrich wheat cookies being the research material. The anti-radical effect of polyphenols present in the fractions with molecular mass<3.0 kDa, with 0.5% and 1.0% addition of herbs against DPPH• and ABTS+• was tested, and the chelating ability of iron (II) ions was additionally tested. Besides, their potential inhibitory activity against enzymes involved in the pathogenesis of MS, i.e. angiotensin-converting enzyme I (ACE), lipoxygenase (LOX), pancreatic lipase, α-amylase, was assessed. Research has shown a statistically significant anti-radical effect against DPPH• of 1% enriched cookies (0.12 mg mL-1) compared to control and 0.5% samples (0.60 mg mL-1, 0.51 mg mL-1, respectively) as well as the highest inhibition value against α-amylase (EC50 0.013 mg mL-1). In addition, the lowest EC50 value against ACE and LOX activity was tested in a sample with 0.5% addition of St. John’s Wort (0.33 mg mL-1, 0.24 mg mL-1, respectively). The antimicrobial properties of the samples were tested against bacteria the results showed fractions with molecular mass<3.0 kDa from 0.5% and 1.0% inhibited the growth of E. coli and B. cereus slightly, but statistically significantly compared to the control sample. In conclusion there have been indicated the food enrichment is a promising manner leading to providing good quality products. The process increased bioactive compounds content in cookies: polyphenols and bioactive peptides simultaneously, characterized by inhibition activity against MS-developing enzymes. Moreover, research have shown uncommon properties of Hypericum perforatum L., alternative to anti-depressant.