Once you reach the age of 50, your body's ability to absorb various vitamins dwindles, according to WebMD - and that can lead to health complications down the road.
A deficiency of vitamin B-12 is closely linked to dementia, and many older Americans start suffering from it when they have too little of the essential nutrient.
Experts say that about one in 20 people older than 60 and one in 10 older than 75 suffer from the mental disease as a direct result of the deficiency.
Not getting enough of the vitamin can lead to brain fog, which can turn into dementia. And as many as one in eight people suffer from such a deficiency, Psyblog, a scientific research blog, says.
Vitamin B-12 aids in the production of red blood cells and helps brain cells function properly. It's also useful in the production of myelin, the material that connects brain cells.
Keeping both of those bodily processes up and running is integral for many facets of physical and mental health, especially as you age.
An increase in trendy vegan and plant-based diets may be to blame for the number of cases, as plants contain little vitamin B-12. That's why many who follow such diets take supplements.
Certain prescriptions, including proton pump inhibitors, can also result in vitamin vacancies.
Deficiencies are generally hard to diagnose, however - fatigue, blurry vision, confusion and mental health issues like anxiety and depression are symptoms, and those can also be symptoms of other issues.
"It is clear that B-12 deficiency is more common than most clinicians appreciate and that the diagnosis is often missed since the symptoms an be quite general," Professor Martin Warren of the Quandrum Institute told The Telegraph. He's an expert in vitamin B-12.
Most diagnoses are made by drawing blood and testing for levels of the vitamin. Heightened risk factors for a deficiency include age, diet and a patient's family medical history.
The National Institute for Health and Care Excellence in the UK recently issued new guidelines for doctors outlining when they should be testing their patients for a vitamin B-12 deficiency.
No set standards have been implemented in the US, though doctors often do blood tests to diagnose other issues that can detect levels of vitamin B-12.
Treatments for the issue include changing your diet to include foods rich in the nutrient, taking oral supplements or getting intramuscular injections.
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