Conflict of evidence: Carotenoids and other micronutrients in the prevention and treatment of cognitive impairment

Abstract

Cognitive impairment is a common age-related disorder which affects in the stadium and type Alzheimer's Disease (AD) a steadily growing number of patients. AD is not curable and is not being easily diagnosed in its preclinical phase. This work aims at highlighting the complex though promising rationale for the use of selected micronutrients against age-related cognitive impairment and its progression. The advances made in the last decades in both defining the etiopathogenesis of cognitive impairment and in revealing mechanisms of action underlying possible preventive effects of several vitamins and micronutrients--likely related to antioxidant activity and modulation of cellular signaling--is being accompanied by conflicting results of most clinical trials. Therefore, available data do not currently support the use of substances such as carotenoids, polyphenols, vitamin D, curcumin, vitamin E, vitamin C, or lipoic acid in AD prevention and/or treatment. This might be partly due to the fact that cognitive impairment and especially AD are extremely complex disorders. The main obstacle to the inclusion of micronutrients among anticognitive impairment drug strategies, however, is that studies conducted so far are poorly comparable and probably underestimate of the role of vascular damage in age-related cognitive impairment. A possible clinical benefit of these substances in AD is not disproved to date, thus further better designed studies are needed.

SOD2 in mitochondrial dysfunction and neurodegeneration

“…Studies in human beings have also found some correlation between markers of oxidative stress and cognitive function (97,98). The ability to modulate a decline in cognitive function with dietary supplements has met with mixed success, and this may be attributable in part to the complexity of cognitive assessment, differences in study design, efficacy of the antioxidants in question, and the difficulty of effectively delivering antioxidants to the brain (99). While the results in human trials are not conclusive, aged C57Bl6 mice treated with catalytic antioxidants maintain their cognitive function better than that of untreated mice (100).…”

Inhibition of GTRAP3-18 May Increase Neuroprotective Glutathione (GSH) Synthesis

“…Indeed, supplementation with ascorbate, α-tocopherol, or both, have failed to produce conspicuous benefit in patients with neurodegenerative diseases such as PD and Alzheimer’s disease (AD) [103–107], although several conflicting lines of evidence have been reported [108–110]. In addition, it was reported that the levels of ascorbate and α-tocopherol in the CNS did not change in patients with PD and AD, compared with controls [27,28,101,111].…”

Influences of Orally Taken Carotenoid-Rich Curly Kale Extract on Collagen I/Elastin Index of the Skin

“…Nutrition rich in fruit and vegetables is beneficial to human health and wellbeing [ 1 , 2 , 3 , 4 ]. Secondary plant components, such as antioxidants [ 5 ], protect the cells and connective tissue against the development of oxidative stress, which is related to several pathological consequences, e.g., neurological [ 6 ], cardio-vascular [ 7 ], dermatological diseases [ 8 ] or aging [ 9 ]. Oxidative stress is induced by various factors, inter alia, solar radiation, smoking, alcohol consumption, lack of sleep, intensive physical activities and psychological stress [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], and therefore cannot be avoided in daily life.…”