Daily consumption of the antioxidant-rich drink for eight months was associated with a smaller increase in homocysteine levels, compared with the placebo group, and the effects were even more significant in people with moderate Alzeimer’s disease, according to findings published in the Journal of the Neurological Sciences.
“The main finding of this study is that patients that took DRAP show lower increase in homocysteine concentrations (especially patients of the moderate phase Alzheimer’s Disease),” wrote researchers from the Catholic University of San Antonio in Murcia in Spain.
“The dietary polyphenolics provide numerous health benefits, such as anti-inflammation and antioxidation […] Our results suggest that polyphenol antioxidant drink can reduce the effects of inflammation and cardiovascular risk associated to Alzheimer's disease,” they added.
Alzheimer’s and homocysteine
Previously, epidemiological studies have reported that high levels of homocysteine are associated with suspected or confirmed dementia. Indeed, the Framingham study reported that people with homocysteine (tHcy) levels above 14 micromoles per liter of serum had twice the risk of dementia.
“It is not clear, however, if an elevation of tHcy concentration is a ‘risk factor’ with a direct pathophysiological role in the development of the disease or merely a ‘risk marker’ reflecting an underlying process such as oxidative stress, responsible for both the high tHcy concentrations and the development of Alzheimer’s disease,” explained the researchers.
“At present we know that elevations in plasma tHcy temporally precede the development of dementia and that there is a continuous, inverse linear relation between plasma tHcy concentrations and cognitive performance in older persons,” they added.
The Murcia-based scientists recruited 100 women to participate in the multicenter, randomized, double-blind controlled clinical trial. Fifty-two of the women were considered generally healthy (no Alzheimer’s) and assigned to the control group, while the other 48 were diagnosed with Alzeimer’s disease (24 women with early-onset and 24 with moderate Alzheimer’s).
Women from all three groups were randomly assigned to one of two interventions: One received a placebo drink for eight months, while the other received an antioxidant beverage rich in polyphenols. The antioxidant beverage was formulated using apple and lemon concentrate juice, apple and green tea extracts, and vitamins B and C.
Results showed that consumption of the antioxidant-rich drink “attenuated the tHcy increase in the control group”, which was measured at a level of 11.7 micromoles per liter for the antioxidant beverage, compared with 15.63 micromoles per liter for the placebo group. Furthermore, in people with moderate Alzeimer’s diseases, the active beverage was associated with an average homocysteine level of 10.49 micromoles per liter, compared with 16.58 micromoles per liter for the placebo group.
“If we take the value tHcy 14.0 micromoles per liter as a ‘risk value’ associated with cardiovascular alterations on neurodegenerative diseases, we can state that this concentration was higher in those subjects that took the placebo drink in the control group and in the group of AD in the moderate phase, whereas the subjects of those groups that took the drink rich in polyphenolic antioxidants beverage maintained their homocysteine levels lower than 14.0 micromoles per liter,” stated the researchers.
“These findings suggest that antioxidant drink diminishes cardiovascular risk associated to hyperhomocysteinemia in Alzheimer's patients,” they added.
The homocysteine hypothesis
Previously, high levels of the amino acid, hyperhomocysteinemia, were said to be a marker for heart disease and thought to be a risk factor for atherosclerotic disease, which contributes to heart attacks.
The link was founded on the observation that children with homocystinuria – a rare genetic condition causing extreme elevations in homocysteine levels – have higher rates of cardiovascular disease. Such an observation was therefore generalized to the wider population, with the hypothesis indicating that supplementation with B vitamins may reduce blood homocysteine levels and reduce the risk of heart disease.
The link between homocysteine and cardiovascular events was questioned recently with results of a meta-analysis of eight folic acid trials involving 37,485 participants finding no benefits on the risk of major vascular events, cancer, or deaths, despite reducing homocysteine levels by 25 per cent.
Researchers from the University of Oxford reported their findings in the Archives of Internal Medicine (Vol. 170, pp. 1622-1631).
Source : Journal of the Neurological Sciences
Published online ahead of print, doi:10.1016/j.jns.2010.08.050
"Effect of an antioxidant drink on homocysteine levels in Alzheimer's patients"
Authors: J.M. Morillas-Ruiz, J.M. Rubio-Perez, M.D. Albaladejo, P. Zafrilla, S. Parra and M.L. Vidal-Guevara