Vitamin B12-deficiency is linked to the depression, dementia, and unhealthy aging. Dietary sources remain the gold standard, but pay attention to the finer details. Absorption and bioavailability matter.   

According to the Anxiety and Depression Association, depression is “the leading cause of disability in the U.S. for ages 15 to 44,” affecting about 6.7% of the U.S. population. When thinking more generally about neurological disorders, the figure is much higher. In Europe it’s estimated that “neuropsychiatric diseases make up approximately 35% of the total burden of disease in Europe.“ [1]

Neurologists are discovering that, despite their very different origins, many of these diseases involve improperly functioning metabolic pathways, largely due to poor nutrition. Within this context, one of the most important micronutrients is Vitamin B12.

The science behind Vitamin B12

Vitamin B12 is so important because of the role it plays in synthesizing compounds that are crucial for a healthy mind and body. This entire process begins with an essential amino acid called methionine. Like Vitamin B12, methionine must be obtained from our diets and is necessary for building proteins. Eggs, fish, and plant seeds are excellent sources. When methionine is properly utilized by the body, it synthesizes DNA, but also neurotransmitters, hormones, fatty acids, and many compounds that are key to making the body operate as it should. Since it plays such a crucial role in DNA synthesis as well as the production of neurotransmitters, proper methionine metabolism is linked to both a healthy brain and healthy ageing. And yet this entire cascade of positive effects can only happen in the presence of Vitamin B12. That micronutrient is what allows us to use methionine effectively.

There’s a flipside to all this. When methionine is consumed from an egg or plant seed and then utilized by the body (by Vitamin B12), one of the by-products is another amino acid called homocysteine. In healthy adults, homocysteine is then transformed back (“remethylated”) into methionine to be used again to synthesize more DNA, neurotransmitters, and all those other important compounds. Yet making use of homocysteine requires the help of--once again--Vitamin B12. When there aren’t enough levels of Vitamin B12 in the body, or someone has an impaired ability to properly use Vitamin B12, homocysteine levels rise. This rise in unused homocysteine has the opposite effect of the methionine pathway described above: Instead of synthesizing “neurotransmitters and proteins important for the structural integrity of the brain,” that entire process becomes impaired.

The result: better methionine metabolism means a healthy brain and longer living. Poor methionine and homocysteine production means an unhealthy brain and unhealthy ageing. The key micronutrient that makes all of this work seamlessly is Vitamin B12. [2]

What happens when someone doesn’t get enough Vitamin B12

Once the basic science behind Vitamin B12 is understood, it becomes clear why there are so many problems and disorders linked to low levels of Vitamin B12 or folate, including:

• Psychomotor retardation in children and adolescents
• Neuropsychiatric disorders in children, adolescents, and adults
• Babies breastfed by vitamin B12-deficient mothers “can be affected by serious and irreversible CNS damage”
• “Forgetfulness, sleeplessness, tiredness, irritability, lethargy and mood swings” in adults
• Depression
• Dementia
• Among the elderly: cognitive impairment, dementia, and Parkinson’s disease
• Atherosclerosis
• Multiple sclerosis
• “Thromboembolic events” and cardiovascular disease  
• Cerebral ischemia
• Accelerated onset of Alzheimer’s disease
• Bipolar disorder
• Epilepsy [2]

Expecting mothers, children, adolescents, and the elderly are particularly sensitive to Vitamin B12 irregularities. When comparing vegetarians, vegans, and meat-eaters, studies have found that vegans are more likely to be Vitamin B12-deficient than other groups. [3]

Supplementing with Vitamin B12

For adults, the RDA of vitamin B12 is 2.4 lg/day in the United States. The only way to get Vitamin B12 is through diet or supplementation.

In dire situations, such as when a Vitamin B12-deficiency is diagnosed in an elderly patient, a cobalamin (Vitamin B12) supplement will be injected directly into muscular tissue [4]. It’s fairly tedious and painful, but remains the medical standard for dire situations.

Spirulina tablets and powders are typically pitched as excellent sources of Vitamin B12. However, when scientists have sampled these sources, they found that most of the Vitamin B12 (83%) were actually pseudovitamin B12, which is “hardly absorbed in mammalian intestine … .” Other studies have shown spirulina Vitamin B12 may not be bioavailable at all in mammals--in fact an extract of spirulina “contains two vitamin B12 compounds that can block the metabolism of vitamin B12” [5]. In short, many studies have shown spirulina to be a poor source of Vitamin B12 for humans.

The Gold Standard: Foods naturally high in bioavailable Vitamin B12

As with many other nutritional requirements, evidence suggests that the best way to get Vitamin B12 is to eat real foods that are naturally high in it: “The overarching and long-term strategy recommended for the control of folate and B12 deficiency is the consumption of a diet that meets the recommended intakes of these vitamins.” [6]  

Meat is an excellent source, but read the fine print

Eggs are often touted as excellent sources of Vitamin B12, but this is where bioavailability becomes relevant. According to a survey of the literature, despite being fairly high in B12, less than 9% is actually absorbed. [7]

Instead, natural Vitamin B12 is highest in fish and shellfish, sheep meat, and chicken. Even here though, when comparing meat sources, farming practices play a crucial role in how much bioavailable Vitamin B12 is actually there. For example, traditionally chicken has had a higher bioavailability than fish, 61-66% vs. 42%; but since Vitamin B12 is collected in animals by eating microorganisms from the soil (or the sea), chickens or beef raised in artificial conditions may not have as much Vitamin B12 [8]. As one news article put it:

“cattle no longer feed on grass and chickens do not peck in the dirt on factory farms. Even if they did, pesticides often kill B12 producing bacteria and insects in soil. Heavy antibiotic use kills B12 producing bacteria in the guts of farm animals. In order to maintain meat a source of B12 the meat industry now adds it to animal feed, 90% of B12 supplements produced in the world are fed to livestock. ...” [9]

When shopping for meat, it’s important to keep in mind that free range organic, grass fed, and pastured-raised will have (naturally) higher levels of Vitamin B12. Other meats may gotten their Vitamin B12 via supplements.  

Insects are an excellent source of Vitamin B12

Since insects feed so heavily on microorganisms in the soil and on plants, it makes sense that they also contain very high levels of bioavailable Vitamin B12. They’re similar in this regard to shellfish (clams, for example, are one of the most efficient Vitamin B12 sources in terms of bioavailability). Being high in B12 was one of the reasons The Scientist recommended consumers to include insects as part of their diet. [10]

One serving of Chapul’s cricket flour (35 g) has 326% of the minimum daily recommended intake.

References

[1] Anxiety and Depression Association of America. “Facts & Statistics.” https://adaa.org/about-adaa/press-room/facts-statistics.

[2] Olaf Stanger, et al. “Homosystein, folate and vitamin B12 in neuropsychiatric diseases: review and treatment recommendations.” Expert Rev. Neurother 9(9), 1393-1412 (2009).

[3] Benjamin Alles, et al. “Comparison of Sociodemographic and Nutritional Characteristics between Self-Reported Vegetarians, Vegans, and Meat-Eaters from the NutriNet-Sante Study.” Nutrients 2017, 9(9), 1023; doi:10.3390/nu9091023.

[4] Monique P.H. Tillemans, et al. “Effect of Administration Route on the Pharmacokinetics of Cobaliamin in Elderly Patients: A Randomized Controlled Trial.” Curr Ther Res Clin Exp. 2014 Dec; 76:21-25. doi:  10.1016/j.curtheres.2014.01.001

[5] Watanabe F., et al. “Pseudovitamin B(12) is the predominant cobamide of an algal health food, spirulina tablets.” J Agric Food Chem. 1999 Nov; 47(11):4736-41.

[6] “Conclusions of a WHO Technical Consultation on folate and vitamin B12 deficiencies.” Food and Nutrition Bullet, 29(2), 2008.

[7] Watanabe, F., “Pseudovitamin B(12)... .”

[8] Watanabe, F., “Minireview: Vitamin B12 Sources and Bioavailability.” Society for Experimental Biology and Medicine. 2007.

[9] Dr. Jennifer Rooke, “Do carnivores need Vitamin B12 supplements?” Baltimore Post-Examiner. 30 Oct. 2013.

[10] Aaron T. Dossey. “Why Insects Should Be in Your Diet.” The Scientist. 1 Feb 2013.