Elizabeth E. Devore, ScD, said:
"These results are interesting because other studies have suggested that antioxidants may help protect against stroke and dementia. It's possible that individual antioxidants, or the main foods that contribute those antioxidants - rather than the total antioxidant level in the diet - contribute to the lower risk of dementia and stroke found in earlier studies."
Not all studies have disagreed with Devore's findings. In March 2012, scientists from the University of California, San Diego, said they found no link between the antioxidant combo of vitamins E, C, and α-lipoic acid (E/C/ALA) and changes in cerebrospinal fluid biomarkers associated with Alzheimer's disease.
Devore and team gathered and examined data on 5,395 people aged 55+ years. 5,285 of them had no history of stroke when the study began. None of them had any signs of dementia at the start of the study.
The volunteers were asked to complete questionnaires which detailed questions regarding their eating habits. The participants provided data on how frequently they consumed over 170 foods during the previous twelve months.
The researchers followed the participants for an average of 13.8 years.
The volunteers were divided into three groups, according to their long-term antioxidant consumption:
- Low level of antioxidants (in their diet)
- Moderate level of antioxidants
- High level of antioxidants
The authors were surprised to find that the levels of antioxidants in their diets made no difference to dementia or stroke risk.
Devore pointed out that most (90%) of the difference in the antioxidant levels in people's diets was due to how much tea or coffee they consumed. Tea and coffee are rich in some non-traditional antioxidants, such as flavonoids.
Coffee is an important source of antioxidants in the USA
Researchers from the University of Scranton found that coffee is the number one source of antioxidants in the US diet. Study leader, Joe Vinson, Ph.D., said "Americans get more of their antioxidants from coffee than any other dietary source. Nothing else comes close."
"This differed from an Italian study that found the higher total antioxidant levels were associated with a lower risk of stroke, where the variation from coffee and tea was lower, and the contribution from alcoholic beverages, fruits and vegetables was higher."
Written by Christian Nordqvist