The Role of Copper in Mental Decline with Age

Summarized by Robert W. Griffith, MD
September 12, 2006

Summary

A high intake of dietary copper in someone already eating too many saturated and trans fats will accelerate the normal age-related decline in mental function considerably.

Introduction

Too much saturated fat and trans-fat in your diet doubles or triples the risk of Alzheimer's disease.¹ A new finding, based on animal studies, throws new light on this. A chance observation of a study in rabbits on a high cholesterol diet showed that those who drank distilled water with a trace of copper in it had an accelerated decline in memory test results, when these were compared with those from rabbits who drank ultra-pure distilled water. And the rabbits drinking the copper-tainted water had amyloid beta plaques in their brains - a diagnostic finding in Alzheimer's.

Rush University scientists designed a study to see if copper plus a high saturated and trans fat diet in older persons was associated with any changes in mental (cognitive) tests over a 6-year period. Their findings are reported in the Archives of Neurology, and summarized here.

What was done

The participants in this study were 6000+ people over 65 living in the community - Chicago - who completed baseline food-frequency questionnaires over a 15-month period. Also at baseline, four tests of cognitive function (mental ability) were administered.² These tests were given again at in-home interviews 3 and 6 years later. The differences in scores from baseline tests were averaged into a single global measurement of cognitive decline for the subject.

Those subjects whose saturated fat intake was in the top 20% and whose trans fat intake was in the top 60% were identified, and analyzed for their copper intake. They were than classified into five groups (quintiles) of copper intake: the highest quintile averaged 2.75 mg copper/day, the lowest quintile 0.88 mg copper/day.

What was found

A total of 3718 subjects provided data for analysis. Their average age was 75, 61% were female, and 60% were African American. The average follow-up period was 5.5 years.

Overall, dietary copper, zinc, and iron were not linked to cognitive decline. However, among the16% of subjects who had high saturated or trans fat intake, mental decline was faster in those with a high copper intake - about 1½ times faster. The researchers estimated that the copper-plus-fat related decline was equivalent to adding 19 years to the age of the highest quintile subjects.

Those with a high copper intake were more likely to have a healthy lifestyle and better cognitive ability, when the whole collective was considered; the link between copper intake and impaired cognitive function was confined to those in the high fats group. And the effect seen with high copper intake was unchanged when subjects in poor health were excluded. Some of the high copper intake subjects in the high fats group were obtaining the metal from copper-containing supplements, and they showed cognitive decline.

What this means

The findings in this prospective study are fairly clear-cut. A high intake of dietary copper (from food and/or supplements) in someone already eating too many saturated and trans fats will accelerate the normal age-related decline in mental function. In the worst cases, this can equal a 19-year advance in the aging brain's diminished function.

One probably shouldn't attach too much importance to the role of copper, in the first instance. Other studies have shown the important detrimental effect of the 'bad' fats, and the present study provides confirmation of this. But the association with a high copper intake may help researchers understand the mechanism of aging changes in the brain. And, in the meantime, maybe one shouldn't take copper-loaded nutritional supplements. The recommended dietary allowance (RDA) is 0.9 mg daily, readily reached in a normal diet.

It's a little ironic that copper is contained in mainly healthy foods - shellfish, navy beans, peas, walnuts, whole wheat, tofu, avocado, chili, and chocolate. And organ meats (liver, chiefly) contain large amounts of copper. Eating a healthy diet while avoiding liver is probably the best advice for those wanting to minimize their risk - but avoiding saturated and trans fats is paramount.

Source

• Dietary copper and high saturated and trans fat intakes associated with cognitive decline. MC. Morris, DA. Evans, CC. Tangney,  et al. , Arch Neurol, 2006, vol. 63, pp. 1085--1088

Footnotes
1. Dietary fats and the risk of incident Alzheimer's disease. M. Morris, D. Evans, J. Bienias,  et al., Arch Neurol, 2003, vol. 60, pp. 194--200
2. The East Boston tests of Immediate Memory and Delayed Recall, the Mini-Mental State Examination, and the Symbol Digit Modalities test.

Related Links
Amyloid Plaques
World's Healthiest Foods: Copper
Micronutrient Information Center: Copper

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