Though the underlying cause of Alzheimer’s disease has yet to be found, there is increasing concern about the role of metals in the development of the disease. “Iron and copper,” for example, “are strongly concentrated within the neuritic plaques and neurofibrillary tangles that represent the hallmarks of the [Alzheimer’s] brain.”
Alzheimer’s disease victims have higher levels of copper in their blood and in the fluid that surrounds their brain, as well as inside their brain. Researchers found that in a slice of Alzheimer’s-diseased brain tissue, the amyloid plaques correspond to copper hotspots. Copper may then make these amyloid plaques more toxic, “leading to increased oxidative stress.” “Free Cu [copper] is extremely efficient in the generation of free radicals,” and when copper is removed with a chelating (metal-binding) drug, the free radical oxidation drops.
Unfortunately, when researchers gave that drug to nine Alzheimer’s patients in a pilot study, it did not seem to have any effect on slowing the clinical progression of the disease. Perhaps we need to prevent the copper buildup in the first place?
“Organ meats and shellfish are the richest food sources of copper,” but should we also consider cutting down on plant sources, such as nuts, seeds, legumes, and whole grains? Copper intake only seems to be a problem when consumed with saturated fat or trans fat.
In the Chicago Health and Aging Project, thousands of elderly Chicagoans were followed for six years. Those who were getting the highest copper doses, largely from multivitamin supplements, combined with a diet high in saturated fats, lost cognition as if they had aged 19 years in a period of 6 years, tripling their rate of cognitive decline. However, copper intake “was not associated with cognitive change when the diet was not high in saturated fats.”
Diet-induced high cholesterol “has been shown to increase the formation and progression of [amyloid] plaques in the brain.” As well, “dietary copper may interfere with clearance of [amyloid] from the brain and may further promote [the plaque] accumulation that results from elevated cholesterol levels.” Copper has been shown to interact badly with amyloid, causing its clumping and the production of hydrogen peroxide, a potent pro-oxidant neurotoxin.
This may explain why the higher the levels of copper, the quicker Alzheimer’s disease may progress, particularly among people with high cholesterol levels.
What do we think may be happening? As cholesterol and copper levels rise, cholesterol is incorporated into the nerve cell membrane, causing it to stiffen. The amyloid protein in the membrane detaches to form plaques, at which point iron and copper generate neurotoxic free radicals. Inside the cell, similar havoc is created. Finally, cholesterol-enriched diets can lead to nerve cell death, DNA damage, and blood-brain barrier disruption.
“In conclusion, the present systematic review suggests that a diet rich in [copper and iron] might aggravate the detrimental effects of a high intake of cholesterol and [saturated fat] on the risk of developing [Alzheimer’s disease].” So, diets rich in saturated fat and deficient in antioxidants appear to promote the onset of the disease, while more plant-based diets would likely suppress its onset. There are compounds in plant foods that not only scavenge free radicals and prevent oxidative damage, but are also known to chelate, or bind up, metals, potentially making them additionally protective against the onset of Alzheimer’s. Therefore, the practical implications could be to eat lots of fruits and vegetables, avoid copper-containing supplements, and avoid high intakes of saturated fat and excessive iron intake.