If you’ve ever looked at a food’s nutrition list or the label on a supplement bottle, you know there is a recommended daily amount for every vitamin and mineral. In the U.S., the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine sets these Recommended Dietary Allowances (RDAs), which they say meet the nutrition requirements for nearly 98 percent of healthy individuals. But when it comes to vitamin B12, new research suggests that the experts may have underestimated—which could be failing to protect your brain from dementia and stroke.
RELATED: Taking This Vitamin Could Protect You From Parkinson’s Disease, New Research Shows.
What does vitamin B12 do?
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Vitamin B12 is essential for red blood cell formation, nervous system function, and the production of DNA, according to the National Institutes of Health (NIH) Office of Dietary Supplements (ODS).
Foods high in the nutrient include beef liver, clams and oysters, nutritional yeast, salmon, canned tuna, ground beef, milk, and yogurt. Some people also take B12 supplements.
As Best Life previously shared, signs you’re not getting enough vitamin B12 include:
- Fatigue (When your body isn’t making enough red blood cells, your cells get less oxygen.)
- Numbness and tingling (Due to altered nerve signals.)
- Anemia
- Infertility
- Mouth or tongue sores known as glossitis
- Pale or yellowish skin
Vitamin B12 deficiency can also cause neurological and cardiac symptoms.
As the ODS notes, several past studies have examined how vitamin B12 deficiency affects one’s risk of developing Alzheimer’s disease or dementia. “Scientists hypothesize that elevated homocysteine levels might have a negative effect on the brain via numerous mechanisms,” they write.
Homocysteine is an amino acid present in your blood that helps to create proteins,
Cleveland Clinic explains. Along with vitamin B6 and folate, vitamin B12 helps to break homocysteine down. A deficiency in one of these vitamins can lead to elevated homocysteine, which could damage the lining of your arteries or cause blood clots and blood vessel blockages, leading to heart attack or stroke.
A new study shows that the current RDA for vitamin B12 may not protect against stroke and dementia.
Now, new research suggests that the current RDA for vitamin B12 may not be high enough to protect against cognitive impairment.
Published in Annals of Neurology, the study analyzed the health data of 231 healthy elderly volunteers (median age 71.2 years old) to assess whether B12 levels within the current “normal” range led to any neurological changes. The participants had an average of 414.8 pmol/L of vitamin B12 in their blood, which is well above the RDA of 148 pmol/L.
However, even at these levels, the researchers observed the following concerning outcomes:
- Cognitive decline: Low vitamin B12 levels were associated with slower processing speeds and reaction times on cognitive tests.
- Increased white matter in the brain: MRI scans of participants’ brains showed larger volumes of white matter lesions, which, as Cleveland Clinic explains, “can damage important pathways (highways) within your brain and can cause problems with memory, balance and walking,” as well as increased risk of stroke and dementia.
Ari J. Green, MD, senior study author and a
professor in the UCSF Departments of Neurology and Ophthalmology and the Weill Institute for Neurosciences, said in a statement obtained by
Neuroscience News, “Previous studies that defined healthy amounts of B12 may have missed subtle functional manifestations of high or low levels that can affect people without causing overt symptoms,” specifying that the most common deficiencies are connected with B12 anemia.
“In addition to redefining B12 deficiency, clinicians should consider supplementation in older patients with neurological symptoms even if their levels are within normal limits,” added co-first author Alexandra Beaudry-Richard, MSc. “Ultimately, we need to invest in more research about the underlying biology of B12 insufficiency, since it may be a preventable cause of cognitive decline.”
The takeaway:
Vitamin B12 deficiency can cause neurological and cardiac symptoms. However, a new study shows that even the current recommended levels of the nutrient may not be enough. Researchers found that elderly adults whose vitamin B12 levels were within the “normal” range still showed symptoms of cognitive decline and had increased white matter lesions in the brain, which could increase the risk for stroke and dementia. The study authors concluded that more research is needed to reassess how much vitamin B12 healthy adults should really have.
