Buyer beware: Results of a recent study at UC San Diego has researchers warning consumers with Alzheimer’s disease (or those in the early stages of it) to avoid taking L-serine supplements.
Advertised to improve cognitive function and slow the progression of Alzheimer’s, L-serine supplements are a version of serine, an amino acid our body naturally produces that’s necessary for neurotransmission in the brain. Without serine, cognitive functioning becomes impaired. L-serine supplements are easily synthesized from protein in the foods we eat and drink, such as a glass of milk, slice of cheese, or a plate of rice and beans.
Conflicting research on brain supplements
A study conducted by UC San Diego researchers last year revealed the post-mortem brains of people at different stages of Alzheimer’s disease contained low levels of PHGDH, the enzyme that produces serine. The findings indicated that upping the amount of serine in the brain might compensate for the deficit, improve cognition and prolong brain functioning. However, a recent study, piggybacking onto last year’s research and published May 3 in Cell Metabolism, resulted in the opposite findings.
Researchers discovered high levels of PHGDH present in the post-mortem brains of people at different stages of Alzheimer’s. Thus, they now advise against taking L-serine supplements. Why? Because an overabundance of the amino acid may cause too many neurons to fire at once and potentially burn out, worsening symptoms and disease states.
“In Alzheimer’s disease, your actual cognitive function is impaired because of hyperactivity of neurons,” explained Xu Chen, professor of neurosciences at UC San Diego School of Medicine and a lead researcher of the study. “That is true for a lot of neurological diseases, such as autism. Initially neurons are just going wild. That’s why caution is needed [with L-serine supplements].”
A breakthrough in Alzheimer’s testing
Chen said PHGDH levels can be traced by a blood test and used as a biomarker to identify patients at risk of developing Alzheimer’s disease, as well as pinpointing an individual’s stage of disease. In the study, blood levels of the enzyme PHGDH were consistent with those in the brain. Still, it’s not a stand-alone test.
“It has to be in combination with neurological tests, imaging, blood tests,” Chen explained. “This is an added criteria or biomarker that will help you predict your progression of Alzheimer’s.”
Andrew Duxbury, MD, professor of clinical geriatrics at UAB School of Medicine, said to take these findings with a grain of salt.
“It’s research done comparing brain tissues in post-mortem individuals,” Duxbury explained. “It’s not research done on living human beings, where [researchers are] studying the actual effect of that substance in the body of someone who is alive and thinking.”
He wonders if the high levels of PHGDH in the brains that were examined are an example of a brain in trouble trying to right itself by attempting to create more PHGDH. Without a scientific answer to that question, he said researchers are assuming if you put serine in the brain to increase the level of PHGDH enzyme, it could advance the disease process.
Don’t panic if you’ve taken an L-serine supplement
“I have never in my practice advised an individual to take L-serine because there really has been no hard evidence of controlled studies in living human beings that it’s of any use,” Duxbury said. “If people come to me having done their own research, saying, ‘I want to try this because it’s a normal component, a protein we’re all eating every day,’ I’ve never said, ‘Don’t do it.’ I believe that human beings know best what works for them. We all live in our own bodies and know what makes us feel the best.”
He’s also not convinced he would use this current research to discourage patients from taking L-serine supplements.
“I cannot recommend it because I don’t have any science [to prove it],” he said, emphasizing again the research was not done on living, functioning human beings. “If you want to try it, I don’t think it will poison you. If you feel better with it or you think it does positive things for you, great. If it doesn’t, spend your money elsewhere.”
Duxbury warns patients that supplements are hardly regulated at all by the FDA. The reality is, there are good manufacturers and bad manufacturers. Bad manufacturers put doses on the label that don’t match what’s inside the bottle, putting consumers at risk of taking too little or too much of a supplement and experiencing potentially harmful side effects or interactions with other medications.
“If a manufacturer cannot be bothered to put their contact information, lot number, expiration date and ingredients on the label,” Duxbury tells patients, “You should not buy it.”
A promising future
While Chen admitted right now no drug is working well to treat Alzheimer’s disease, the medication memantine does calm down neurons and may improve some memory or awareness. Her team hopes if they continue to examine how PHGDH gene expression affects disease outcomes, it will lead to new therapeutics for Alzheimer’s.
In the meantime, Duxbury advises talking to your doctor before discarding your supply of L-serine.
“Different people approach these problems differently,” he said. “When you’re dealing with something as disastrous in a life and tragic as Alzheimer’s disease, where we have no cures, anything that helps a particular individual is a good thing.”