Do antioxidant-rich diets lower the risk of stroke and dementia?
By Sophie Ramsey
Contrary to previous findings, people who have high levels of antioxidants in their diet may not have a lower risk of dementia and strokes, a new study suggests. But it could be that high amounts of specific antioxidants help.
Antioxidants are nutrients that help to protect your cells from damage caused by 'free radicals'. These are harmful molecules that doctors think may play a role in heart disease, cancer, and other illnesses.
There are lots of different types of antioxidants, including vitamin C, vitamin E, carotenoids, and flavonoids. They are found in many foods, including fruit and vegetables, nuts, grains, tea, coffee, red wine, and dark chocolate.
Some studies have suggested that people who eat more of these antioxidant-rich foods have a lower risk of problems affecting their brain, such as strokes and dementia. But others have found no link.
To explore this further, Dutch researchers looked at the types of food eaten by 5,295 people aged 55 and older who lived in Rotterdam. The participants filled in detailed questionnaires on their health, lifestyle, and how often they ate any of 170 different foods. From this, the researchers divided the participants into three groups, based on whether they had low, moderate, or high overall levels of antioxidants in their diet. They then looked at whether the participants developed dementia or had a stroke during nearly 14 years of follow-up research, and whether there was a link between the amount of antioxidants people ate and their risk of these health problems.
People with the highest levels of antioxidants in their diet were just as likely to develop dementia or have a stroke as those with the lowest levels. The findings were the same when the researchers looked at different types of dementia, such as Alzheimer’s disease and vascular dementia, and different types of strokes, such as ischaemic and haemorrhagic strokes.
Overall, about 600 people had a stroke during the study and about 600 were diagnosed with dementia.
This was a large, well-conducted study. To arrive at these findings, the researchers took into account several things that can affect a person’s chance of having a stroke or dementia. These included their age, their use of dietary supplements, and whether they smoked, had certain genes linked to dementia, or had other conditions that raise the risk of a stroke, such as diabetes. This strengthens the findings of the study.
However, we can't be certain of these results, as other studies have come to different conclusions. These conflicting results may be due to differences in the participants' diets and the types of antioxidants they consumed. In this study a high percentage of the participants' antioxidants came from coffee and tea, while in other studies participants consumed more antioxidants from alcoholic drinks, fruit, and vegetables.
These differences support the idea that amounts of specific antioxidants may be more important in lowering the risk of disease than overall antioxidant levels.
Diets rich in antioxidants are often high in fruit, vegetables, nuts, and other foods that we know are good for you. So even though we're not sure whether high overall antioxidant levels reduce the risk of dementia and strokes, we do know that these nutrients - and the foods they come from - have other health benefits.
Devore EE, Feskens E, Ikram MA, et al. Total antioxidant capacity of the diet and major neurologic outcomes in older adults. Neurology. 2013; 80: 904-910.