**6. Phenolic acids**

Phenolic acids contain a phenolic ring and a carboxyl functional group. Some examples of phenolic acids are protocatechuic acid, vanillic acid, p-hydroxybenzoic acid, ferulic acid, caffeic acid, p-coumaric acid, sinapinic acid, and syringic acid. Phenolic acids are absorbed through the walls of the intestine and serve beneficial roles, such as antioxidants and protect cellular damage by free-radical oxidation reactions.

#### **6.1 Sources**

Sources of phenolic acids are cereals, oilseeds, legumes, vegetables, fruits, beverages, and herbs. Besides these sources, they are also found in all food groups.

#### **6.2 Function**

Phenolic acids have several health benefits, such as intake of phenolic acids decrease the risk of cardiovascular diseases, certain cancers, type II diabetes, and neurodegenerative disorders [60–62], through multiple putative mechanisms of actions, including antioxidation, glucoregulation, anti-inflammation, antiproliferation, and microbial modulation. Russo et al. [63] found a negative relationship between dietary intake phenolic acids (e.g. ferulic acid and caffeic acid) and prostate cancer and they showed that both phenolic acids are associated with reduced prostate cancer. Also, immunoregulation diseases, asthma, and allergic reactions are protected by caffeic acid which is phenolic acid. Caffeic acid has a positive role against colon cancer [64] and it has inhibitor properties of HIV-1 that act as a potential antiviral therapy [65]. It is also found that a higher intake of phenolic acids is significant lower mean systolic and diastolic blood pressure compared to a lower intake of phenolic acids [66].
