It has long been understood that vitamins and minerals act as cofactors in biochemical reactions in the body. They are the “sparks” that set things in motion; without them important processes cannot proceed. Some of these processes contribute to the building and maintenance of the body’s physical structure. For example there’s vitamin D for healthy bone tissue and vitamin C for the synthesis of collagen—a connective tissue found in bone skin tendons ligaments and more.

Another vitamin that’s critical for generating and maintaining healthy tissue is B12. This vitamin contributes to the formation of myelin which is a protective covering that surrounds neurons—nerve cells that originate in the brain and spinal cord and which are responsible for healthy cognitive function and motor coordination—thinking and moving. Severe B12 deficiency results in a number of signs and symptoms that affect multiple body systems. Some of these can be reversed when stores of this nutrient are replenished but others may be irreversible. 

Two groups of people tend to be at higher risk for B12 insufficiency than the general population: elderly people and strict vegetarians/vegans. Many older people may be taking stomach acid blocking medication which will inhibit the body’s ability to absorb this vitamin. (Robust stomach acid is required to “liberate” B12 from the foods it comes in.) Additionally due to decades of guidance from government nutrition authorities to reduce consumption of foods rich in saturated fat and cholesterol people may be avoiding some of the primary dietary sources of B12 such as red meat (liver in particular) egg yolks and shellfish. Additionally older people might steer clear of these foods if they find them more difficult to chew and reduced stomach acid will make them harder to digest as well. 

It is especially troubling that older people might be deficient in this nutrient because B12 is critical for healthy cognitive function. Because of B12’s role in building healthy brain cells B12 deficiency can result in memory loss disorientation and dementia. It would be tragic if an older patient were to be misdiagnosed as having Alzheimer’s disease when the cause of changes in their cognition and behavior was actually a vitamin deficiency. Researchers say that low vitamin B12 status is a risk factor for loss of brain volume in older adults—actual shrinking of the brain.

Compared to patients with other types of dementia Alzheimer’s disease patients have been found to have lower levels of B12 in their cerebrospinal fluid—the substance that nourishes the brain and central nervous system. Increased blood concentrations of B12 are associated with slower rates of cognitive decline whereas increases in markers for B12 insufficiency are associated with a 50% more rapid cognitive decline. These stark findings show how important maintaining optimal nutrient stores is to something as fundamental as being able to think remember and be in control of one’s behavior.

Vitamin B12 deficiency doesn’t just affect older people. Another group at risk for potentially irreversible effects from low nutrient status is children born to parents following strict vegetarian diets. The most concentrated sources of B12 are animal proteins. Lacto-ovo vegetarians may get sufficient amounts from eggs and dairy products but those who avoid animal-sourced foods altogether may have difficulty maintaining adequate stores without careful supplementation. Children of strictly vegetarian parents have experienced developmental difficulties resulting from decreased synthesis of protective myelin. These include severe psychomotor retardation frontoparietal cranial atrophy and the more general catch-all “failure to thrive.” Most disturbing is that even when healthy B12 levels are restored there may be some degree of long-lasting neurocognitive defects later in child development. 

This is not to be overly alarmist. It is simply to emphasize that parents and prospective parents following strictly vegetarian diets should be aware that B12 insufficiency during pregnancy and lactation may lead to potentially irreversible compromises in physical and neurological development during this critical period of growth and development.

Sources

1. Nourhashemi F et al. Alzheimer disease: protective factors. Am J Clin Nutr. 2000 Feb;71(2):643S-649S.
2. Vogiatzoglou A et al. Vitamin B12 status and rate of brain volume loss in community-dwelling elderly. Neurology. 2008 Sep 9;71(11):826-32.
3. Dror DK Allen LH. Effect of vitamin B12 deficiency on neurodevelopment in infants: current knowledge and possible mechanisms. Nutr Rev. 2008 May;66(5):250-5.
4. von Schenck U Bender-Götze C Koletzko B. Persistence of neurological damage induced by dietary vitamin B-12 deficiency in infancy. Arch Dis Child. 1997 Aug;77(2):137-9.