Oxidative stress from age-related increase in free radicals may be responsible for neurodegenerative diseases such as Alzheimer’s. Antioxidants such as vitamin E, vitamin C, and ginkgo biloba may help neutralize these free radicals. Within the last few decades, there has been an intensive research effort to examine antioxidants’ effects on both the prevention and treatment of dementia.
Two very encouraging studies report positive results of antioxidant vitamins on the brains of older adults.
The first study, in the Netherlands, involved 818 adults aged 50 to 70 years old, who received either 800 milligrams (mg) daily of folic acid or placebo for three years. In the folic acid group, memory, information processing speed, and sensorimotor (anything involving both sensory and motor functions) speed were significantly better.
Blood folate levels increased by 576% and total homocysteine levels decreased by 26%. Low blood folate levels and raised homocysteine blood levels have long been implicated in poor cognitive functions in the general population.
The second study, in France, involved 4,447, adults 45 to 60, who received a daily supplement of antioxidant vitamins and minerals or placebo for eight years. The antioxidant contained 120 mg of vitamin C, six mg of beta-carotene, 30 mg of vitamin E, 100 micrograms (ug) ofÂ selenium, and 20 mg of zinc. They found the antioxidantÂ group had better memory (episodic memory, semanticÂ fluency, verbal memory) functions compared to those onÂ placebo.
Verbal memory was significantly improved by the antioxidant supplementation only in those subjects who were nonsmokers or those with low levels of vitamin C in their blood at baseline.
Both of these studies emphasize the point that middle-aged people are the key target population for studying the effects of antioxidant supplementation on the prevention of cognitive decline.
There are a few fine points to consider. Many of the antioxidant vitamin studies failed to yield positive results. It is possible that most of these studies were of short duration with small numbers of subjects. Since the changes in the brain that lead to a decline in cognitive function start in early adulthood, it would be difficult if not impossible to reverse if any treatment started too late in
life. There may be a particular stage in aging that is more sensitive to antioxidant supplements. And antioxidants work as a system. Therefore, the effectiveness of any antioxidant may depend on adequate blood levels of other antioxidants and minerals.
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