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This Nutrient Deficiency Is Associated With Depression

Analysis by Dr. Joseph Mercola


Research published in December 20211 using data from the Irish Longitudinal Study on Aging (TILDA) discovered those with a vitamin B12 deficiency had a greater risk of symptoms of depression. According to the Anxiety and Depression Association of America,2 264 million people worldwide live with symptoms of depression. In 2017, roughly 17.3 million adults in the U.S. had experienced at least one major depressive episode.

This number rose in 2019 to 19.4 million adults who had experienced at least one major depressive episode.3 It is not uncommon for someone who has depression to also suffer from symptoms of anxiety.4 According to the CDC,5 data from the National Health and Nutrition Examination Survey show women are roughly twice as likely to experience depression as men, which was a pattern that was observed in each age group surveyed.

Symptoms of depression can include feeling sad or empty, hopeless, irritable, worthless and restless. You may have difficulty sleeping, experience appetite or weight changes or have thoughts of death or suicide. Not everyone experiences every symptom. For some individuals, their symptoms make it difficult to function.6

The December 2021 study linked deficiencies in vitamin B12 with the incidence of symptoms of depression in the elderly. Vitamin B12 is a water-soluble vitamin found in some foods.7 It's also available as a prescription medication and dietary supplement. Your body uses vitamin B12 for the function and myelination of the central nervous system, to form healthy red blood cells and in DNA synthesis.


Food sources include those of animal origin, such as pasture-raised poultry, dairy products, eggs and meat. Absorption of vitamin B12 is dependent on intrinsic factor, which is a transport and delivery binding protein produced in the stomach.8 The bioavailability from food decreases when the amount of vitamin B12 exceeds the capacity of intrinsic factor.

Vitamin B12 is released from food by the activity of hydrochloric acid and gastric protease in the stomach and saliva in the mouth.9 In 1999 it was estimated10 that vitamin B12 deficiency affects up to 15% of people over age 60. In this study, however, classic symptoms of deficiency were often lacking in this population.

The low vitamin B status is attributed to the high prevalence of atrophic gastritis which results in low-acid pepsin secretion and reduces the release of vitamin B12 from food. The 2021 study finds these low levels of vitamin B12 may increase the risk of depression in older adults.11

Vitamin B12 Deficiency Associated With Depression

The study published in the British Journal of Nutrition12 sought to evaluate the relationship between vitamin B12, folate and the incidence of depression in older individuals living in the community. There were 3,849 individuals over age 50 included.

The results showed a link between vitamin B12 deficiency, but not with a folate deficiency.13 The researchers found that even after controlling for factors such as chronic disease, cardiovascular disease, antidepressant use, physical activity and vitamin D status, the results remain significant.14

The older adults who had a B12 deficiency had a 51% increased risk of developing symptoms of depression during the four years of the study. The data also showed that certain factors influenced the vitamin B12 status in older adults. This included geographic location, obesity, smoking, socioeconomic status and gender.

While the link was found between older adults living in the community and a vitamin B12 deficiency, they also found that older individuals in the study had a lower risk of depression. In a press release from Trinity College Dublin, Eamon Laird, from TILDA15 and lead scientist of the study talked about the results in a press release, saying:16

“This study is highly relevant given the high prevalence of incident depression in older adults living in Ireland, and especially following evidence to show that one in eight older adults report high levels of low B12 deficiency rates.
There is a growing momentum to introduce a mandatory food fortification policy of B-vitamins in Europe and the UK, especially since mandatory food fortification with folic acid in the US has showed positive results, with folate deficiency or low status rates of just 1.2% in those aged 60 years and older.”

Vitamin D Deficiency Plays a Role in Mental Health

This recent study highlights the importance of adequate nutrition to protect your optimal health. In addition to vitamin B12, other nutrients have a significant effect on mental health. Vitamin D is one of those nutrients. Vitamin D, also known as calciferol,17 is a fat-soluble vitamin, which your body can absorb from a few foods and produces endogenously when exposed to sunlight.

People can become deficient when they consume less than the recommended level, have limited exposure to sunlight, their absorption from the digestive tract is inadequate, or the kidneys do not convert the vitamin to its active form. Scientists believe that vitamin D deficiency is a vastly overlooked global health problem at epidemic proportions.18

How vitamin D deficiency is defined also varies. For the most part, researchers interpret vitamin D deficiency as serum levels of 25(OH)D at 20 nanograms per milliliter (ng/mL) or less.19 However, optimal serum levels of vitamin D are between 40 ng/mL and 60 ng/mL.20

Early research in 200021 demonstrated there were significantly deficient levels of vitamin D3 in patients who suffered from depression and alcohol addiction. By 2007, researchers had recognized the importance of low levels of vitamin D on mood.22

Further research23 found individuals with fibromyalgia also had a higher risk of low serum levels of vitamin D and it appeared that supplementing with high doses of vitamin D in individuals who were depressed and overweight could ameliorate the symptoms.24 Over the years, researchers continue to ask the question if vitamin D is a causal association with depression or another symptom of the condition.25

Other scientists postulated whether an effective therapy for depression would be the detection and treatment of vitamin D deficiency.26 By 2014,