By David Liu, PHD

Saturday Jan 5, 2013 (foodconsumer.org) -- Millions of American men and women live with Alzheimer's disease (AD), a disease that has no cure and eventually leads to death.  Three studies reported in the January 2013 issue of Journal of Nutritional Biochemistry suggest that taking certain antioxidant supplements or eating antioxidant-rich functional foods may help prevent the disease or help patients with the disease.

Anthocyanin-enriched bilberry and blackcurrant extracts

One study led by S. Vepsäläinen from Institute of Clinical Medicine-Neurology, University of Eastern Finland in Kuopio, Finland and colleagues shows that anthocyanin-enriched bilberry and blackcurrant extracts alleviate behavioral abnormalities in mice with a medical condition similar to human Alzheimer's disease.

It has been known that fruit and vegetable juices containing phenolic compounds can reduce risk of Alzheimer's disease.  The researchers conducted studies and found not all food compounds have the same effect on the altered amyloid precursor protein (APP) processing which leads to increased β-amyloid (Aβ) production in Alzheimer's disease.

In the study, myricetin, quercetin or anthocyanin-rich extracts were found able to decrease menadione-induced production of reactive oxygen species (ROS) in a dose-dependent manner in human SH-SY5Y neuroblastoma cells overexpressing APP751.  Oxidative stress from ROS is linked to neuroinflammation in Alzheimer's disease.  However, these compounds were not able to influence the APP processing.

In comparison, anthocyanin-rich bilberry and blackcurrant extracts can decrease the APP processing in mice with Alzheimer's.  And both berry diets were able to alleviate the spatial working memory deficit in aged mice with the disease, compared with their counterparts eating a control diet.

The researchers concluded "These data suggest that anthocyanin-rich bilberry and blackcurrant diets favorably modulate APP processing and alleviate behavioral abnormalities in a mouse model of AD."

Organoselenium dietary supplementation

Another study led by S. Pinton  from Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria in Santa Maria, Brazil and colleagues suggests that organoselenium dietary supplementation can help Alzheimer's disease.

Selenium as an antioxidant may help fight Alzheimer's disease because the development of the disease has something to do with oxidative stress and neuroinflammation.

For the study, the researchers first exposed male Wistar rats to streptozotocin, an antibiotic that is commonly used to induce many diseases such as diabetes in animal studies, for 21 days to develop a sporadic dementia of Alzheimer's type (SDAT) and then let them eat a regular diet supplemented with p,p'-methoxyl-diphenyl diselenide - (MeOPhSe)(2), an organic selenium compound, for 30 days.  Then at the end of the supplementation, the rats were examined for their memory and cognitive impairment.

As a result, selenium supplement reverted the antibiotic-induced memory impairment in the rats.  Biochemically, selenium supplementation also reverted oxidative stress in the rats suffering Alzheimer's, that is, decreasing reactive oxygen species and tyrosine nitration levels and enhancing nonprotein thiol levels.

Additionally, the dietary supplement also normalized Acetylcholinesterase activity, which was increased by the antibiotic injection although it did not revert the deficit in cerebral energy metabolism caused by the antibiotic (This indicates that this antibiotic can cause irreversible damage). 

The researchers concluded "The results of the present study indicated the therapeutic effect of the (MeOPhSe)(2)-supplemented diet in a rat model of SDAT."

Green tea compound Epigallocatechin-3-gallate (EGCG)

A study led by Y. J. Lee from Chungbuk National University in Korea and colleagues shows that Epigallocatechin-3-gallate is able to prevent systemic inflammation-induced memory deficit and amyloidogenesis, which are found in Alzheimer's disease.

According to the researchers, it is known that neuroinflammation plays an important role in the pathogenesis or development of Alzheimer's disease through amyloidogenesis. 

For the study, mice first received EGCG in a dose of 1.5 and 3 mg/kg orally for three weeks and then received lipopolysaccharide (LPS) by intraperitoneal (ip) injection (250 ug/kg) for seven days to induce neuroinflammation and memory impairment.

EGCG treatment was found to prevent LPS-induced memory impairment and apoptosis of neuronal cells and suppress LPS-triggered increase in the amyloid beta-peptide level and the amyloid precursor protein (APP).   

EGCG were also found to cause a series of physiological and biochemical responses that indicate this green tea compound may help prevent Alzheimer's disease or help memory impairment in people with the disease.

The researchers concluded "this study shows that EGCG prevents memory impairment as well as amyloidogenesis via inhibition of neuroinflammatory-related cytokines released from astrocytes and suggests that EGCG might be a useful intervention for neuroinflammation-associated AD."