Influence of Imidazole-Dipeptides on Cognitive Status and Preservation in Elders: A Narrative Review

Abstract

The worldwide increase in the number of patients with dementia is becoming a growing problem, while Alzheimer’s disease (AD), a primary neurodegenerative disorder, accounts for more than 70% of all dementia cases. Research on the prevention or reduction of AD occurrence through food ingredients has been widely conducted. In particular, histidine-containing dipeptides, also known as imidazole dipeptides derived from meat, have received much attention. Imidazole dipeptides are abundant in meats such as poultry, fish, and pork. As evidenced by data from recent human intervention trials conducted worldwide, daily supplementation of carnosine and anserine, which are both imidazole dipeptides, can improve memory loss in the elderly and reduce the risk of developing AD. This article also summarizes the latest researches on the biochemical properties of imidazole dipeptides and their effects on animal models associated with age-related cognitive decline. In this review, we focus on the results of human intervention studies using supplements of poultry-derived imidazole dipeptides, including anserine and carnosine, affecting the preservation of cognitive function in the elderly, and discuss how imidazole dipeptides act in the brain to prevent age-related cognitive decline and the onset of dementia.

Protein-Balanced Dietary Habits Benefit Cognitive Function in Japanese Older Adults

“…In particular, animal proteins, including meat, are an excellent source of protein because of their high protein absorption rate, and a high protein diet with a high proportion of meat has been reported to significantly improve cognitive reaction time in randomized intervention trials [ 50 ]. In particular, imidazole dipeptide, a histidine-containing dipeptide found in meats such as pork, poultry, and fish, has attracted attention as an animal peptide with cognitive function protective effects [ 51 ]. In fact, our RCT studies in humans have shown that mixed consumption of anserine and carnosine [ 52 , 53 , 54 , 55 ], as well as anserine alone [ 13 ], is beneficial for cognitive decline in older adults.…”

Effects of Dietary Food Components on Cognitive Functions in Older Adults

“…The effects of MKP on human cognition were also investigated [200]. Furthermore, imidazole-containing amino acids and dipeptides are known as antioxidants in general [201,202]; carnosine in the histidine metabolism pathway has been reported to decrease in AD plasma [203]. Moreover, glutathione is also known as an antioxidant for the cellular detoxification of ROS in the brain [45,204].…”

Covid-19, Carnosine and Cognition

“…33 Carnosine also facilitates macrophage-mediated clearance of senescent cells. 34 It is likely that carnosine's effects are multifactorial, not only can the dipeptide affect metabolism, but it has recently been shown that prolonged fasting causes blood levels of carnosine (presumably intra-erythrocytic) to increase 35 along with a number of other anti-oxidants. A recent study has produced evidence suggesting that carnosine may act as an inhibitor of angiotensin-converting enzyme 2 (ACE2) which could then inhibit viral cellular entry via this protein.…”

“…resistant to serum carnosinase) are strongly associated with frailty in humans. 41 There have been a number of studies on the possible effects of dietary carnosine supplementation in humans 34,42 but the presence of serum carnosinase which ensures the rapid destruction of the dipeptide, limits the impact of dietary-supplied dipeptide. It is likely that the majority of carnosine in blood is due to its presence within erythrocytes; presumably the dipeptide is synthesized during erythropoiesis.…”