Array 
The discovery of metals and their use for the benefit of humankind has played a pivotal role in the evolution of modern society. From huge machinery to everyday utensils, metals have become indispensable. For example, aluminium, copper, and iron are extensively used for cooking as they are strong, durable, and safe.
Sneaking into the body
Over the past few decades, scientists have increasingly found evidence of tiny metallic particles – nanoparticles — leaching into food. Metal nanoparticles of aluminium, arsenic and iron from cooking vessels, packaging, and cutlery are finding their way into our food, water, air, cosmetics and even medicines.
“The metals we use daily, such as utensils for cooking, can release a significant amount of nanoparticles into our food. This is similar to how Teflon and BPA can leach into our food and water,” says Shruti Sethi, a nutritionist and founder of Awaana Health Pvt Ltd, Goa.
There are other ways for metals to enter our body and cause damage to organs and the nervous system, says Sethi. Due to pollution and industrial contaminants entering water bodies, heavy metals like mercury, lead and cadmium find their way into our bodies via seafood. Fish absorb these metals, which get stored in their tissues. When larger fish eat the smaller ones, the metals percolate up the food chain.
Stress on brain cells
Studies show that metal toxicity poses a hazard to brain health. Sethi explains that these metal nanoparticles can hamper neuronal functions by damaging the cells and causing inflammation and oxidative stress.
Damaged neurons are precursors to various neurodegenerative conditions such as Alzheimer’s and Parkinson’s. “At one time, one of my clients, who had cancer, came to us with signs of high inflammation in the body. Suspecting metal toxicity, I suggested relevant metal toxicity blood tests,” says Sethi. The tests revealed that metals like aluminium had remained in his body long after his previous tests. Some studies also show aluminium accumulates and stays for long in the brain, she adds.
Read more: Tug of war: new insights on movement control in Parkinson’s
Disrupting the powerhouse of cells
The human brain is a complex organ that relies on the proper functioning of various cells, like neurons and glial cells. One intracellular component (organelle) of these cells is mitochondrion.
Mitochondria convert glucose and oxygen into energy molecules called ATP (adenosine triphosphate) inside cells. When metal nanoparticles enter the brain, they can disrupt the energy synthesis mechanism in cells. As neurons require high levels of energy to function, any shortage in the overall required energy can disrupt the functioning of neuronal networks, potentially resulting in neurological disorders.
Dr Koyeli Mapa, a life science scientist at Shiv Nadar Institute of Eminence, Delhi NCR, says that various mitochondrial structural changes, such as mitochondrial fragmentation and dysfunction, have been observed in people with Alzheimer’s and Parkinson’s.
“Usually, the brain requires a lot of energy and oxygen. So, when there is mitochondrial dysfunction, there is a shortage in ATP production – the energy molecule of the cell. Hence, the first effect is frequently seen in such high-energy requirement organs,” Dr Mapa tells Happiest Health.
In addition to being the powerhouse of cells, mitochondria also play a role in other metabolic activities such as cholesterol breakdown. If there is any dysfunction in the mitochondria, all of these bio-synthetic pathways can be disrupted, she adds.
Neurological conditions extend beyond mitochondrial malfunction, and their full extent is not yet comprehended by scientists. Alzheimer’s disease, specifically, has been linked to metal toxicity. Studies have shown that metal toxicity can lead to the accumulation of beta-amyloid plaque, which is responsible for cognitive decline associated with the condition.
Similarly, studies have shown that excessive exposure to metals such as manganese and iron can cause oxidative stress in the brain, leading to the death of dopamine-producing neurons. The result: developing tremors and other motor symptoms associated with Parkinson’s condition.
Read more: Genes at play: uncovering the link between DNA changes and Alzheimer’s
Tackling the issue
While metal toxicity can be concerning, several preventive measures and lifestyle changes can significantly reduce these risks. Currently, there are no exact guidelines to determine the hazardous amount of metal nanoparticles in the body, but rough estimates do exist.
Sethi explains,“Avoiding the use of aluminium utensils, being conscious of the consumption of seafood and products containing heavy metals in the form of metallic salts of lead, arsenic, mercury, aluminium, zinc, and chromium. Cosmetics and antiperspirants containing aluminium salts can significantly reduce the risk of many health conditions.”
In addition, Dr Mapa says that our body’s defence mechanism can help eliminate irregular cellular activities to some extent via a self-repair mechanism called mitophagy, where the cells eat away damaged mitochondria to save the cell.
“In another phenomenon, healthy cells donate mitochondria to diseased ones through intercellular duct-like structures. However, these functions have a threshold limit, and anything above will lead to cell death,” cautions Dr Mapa.
Such self-repair mechanisms are extensively being explored in the field of regenerative medicine to develop newer and promising therapies for neurodegenerative disorders.
