Aluminum and the human diet revisited
Abstract
Concerns about aluminum (Al) exposure in the human diet have persisted for one century. We suggest that continued research would benefit from better reporting of environmental factors that are known to influence Al accumulation in plant organs that are consumed, focusing on subsets of the general public that exhibit the highest risk for neuropathological responses, increased evaluation of commercial processing procedures that may concentrate Al or other toxic substances, and designing studies with low dose, chronic exposure rather than further study of acute, brief exposure.
Areas of Concern
To view Al in biological systems as either inert or without toxic consequence is to ignore a rapidly growing body of evidence to the contrary. Inter-disciplinary teams may offer the most efficient means of advancing our understanding of risks of Al exposure in the human diet and from other sources. The following are issues to guide ongoing research.
• Aluminum availability to plants is governed by soil pH, and in accumulator plant species by age of organ. Our study revealed that young noni leaves from trees growing in alkaline soils posed minimal calculated risk, but old leaves from trees growing in acidic soils posed the greatest risk.7 During recent years, substantial advances have been made in understanding the mechanisms of Al toxicity in plants and approaches to assess the potentially toxic Al species in environmental samples.33 Yet soil traits, harvested organ age, and other arguably mandatory experimental details are omitted from research articles on traditional knowledge and folk medicines. These omissions do not acknowledge the current status of knowledge and disallow adequate comparisons among studies.
• Consumption of unprocessed herbal products or home concoctions carries relatively minimal risk of excessive Al exposure. However, superfruits, nutritional therapeutics, neutraceuticals, and functional foods are among the arsenal of innovative marketing strategies to reach consumers who demand what they believe to be healthy food options.34-36 Some commercial procedures concentrate herbal products, then boast about the supposed added benefits of the concentrated product. These processing and concentrating steps may take a raw herbal product that carries minimal risk and turn it into an internationally marketed product that carries greater risk.
• Risks of Al toxicity are elevated for some easily defined subsets of the general public. For example, infants and small children carry greater risk because intake limits are based on body weight and individuals with kidney immaturity or abnormalities because the normal pathway for excreting aluminum from the body is via urine and feces.37 Continued research on pediatric, geriatric, and other high risk groups rather than the general population may increase efficiency of research.
• Numerous investigations have revealed that the chronic component of exposure to Al is what leads to neurotoxicity.8,17 The body burden of Al is spread among various tissues, but incremental doses of small amounts of Al over a lifetime favor brain tissues as the site of bioaccumulation. This form of exposure reproduces neuropathological traits of Alzheimer Disease. Long-term studies on chronic exposure to Al should be the thrust of dietary research.
• Al compounds are numerous, and the biological responses may be highly specific to the form of Al to which the body is exposed. Studies should be specific to the form of aluminum administered.
A high percentage of the world’s population uses alternative self-medication and herbal treatments for prophylactic purposes without being aware of the possible toxic components and toxin synergies that may impact their health. When these herbal treatments inadvertently contain Al or other known toxins, environmental conditions, post-harvest treatment in processing, and age, general health, and genetic traits of the consumer are factors that may increase risk of developing neurological disorders. These examples illuminate why the public should be better informed on health risks associated with using herbal products in self-medication.38
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3914913/