Compared to healthy older adults, intakes of all nutrients may be lower in older adults with diagnosed cognitive impairment or Alzheimer's Disease, however it is unclear whether low levels of nutrients precede or are the consequence of cognitive impairment. In addition, antioxidant intake at supplemental levels demonstrated no difference in the delay of cognitive decline. Additional research is needed in this area.
 

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

While studies on healthy older adults consuming recommended levels of antioxidants generally reported no association with impaired cognitive function, studies regarding antioxidant intakes below recommended levels reported an association with cognitive decline. Research on antioxidant intakes at supplemental levels are inconclusive; conflicting results may be due to genetic factors and prior nutrient deficiencies. Further research is needed in this area.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

Studies have found a beneficial effect of beta-carotene, vitamin C, vitamin E, lutein, zeaxanthin, zinc and copper from diet or supplementation on delaying progression of advanced age-related macular degeneration. However, other studies have reported inconclusive findings. Further research is needed, given the risks of over supplementation.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

Regarding the development of age-related macular degeneration, findings from studies of antioxidant intake below or above recommended dietary allowance (RDA) levels are inconclusive. Further research is needed, given the risks of over-supplementation.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.