Nutrition & Depression: Is There a Link?

By August 16, 2019 No Comments
Photo by Kat Jayne from Pexels

Ever feel depressed?  We all do at times!  However, there is a difference between feeling down when you get bad news or go through a difficult life experience and being clinically depressed.  If your feelings of sadness linger, are excessive, or interfere with your work, sleep, or everyday interests you may be experiencing major depression.  Individuals suffering from major depressive disorder or clinical depression don’t just bounce back or “pull themselves together”.  Recovering from these episodes usually requires treatment, medication, or both.

There are some “non-traditional” ways to treat depression as well.   These treatments are called alternative, integrative, or complementary treatments.  Diet, exercise, mental conditioning, and lifestyle changes are all considered disciplines within the alternative therapy approach.

As a dietitian, of course I am most interested in the nutritional deficiencies, as well as nutrition interventions that are tied to depression.  Here is what the most recent nutrition research is suggesting may contribute to increased mood imbalances and depressive episodes:

Vitamin D

Vitamin D is a neurosteroid hormone that may play an important role in the development of depression.  With over two-thirds of the population of the United States and Canada presenting with suboptimal levels of vitamin D, this has been a unique area of interest in depression research.  Receptors for vitamin D are present in many areas of the brain and vitamin D is involved in several important brain processes including neuroimmunomodulation, regulation of neurotrophic factors, neuroprotection, neuroplasticity and brain development.  Some research suggests that vitamin D might be associated with depression and that supplementation might play an important part of treatment.

The recommended dietary allowance (RDA) for vitamin D for adults is 600 IU.  Vitamin D does not occur naturally in a lot of foods; however, you can find it in fatty fish, fish liver oils, beef liver, cheese, and egg yolks.  Many foods are now fortified with vitamin D, including cow’s milk, cheese, yogurt, breakfast cereals, and plant milk alternatives.  Supplementation is warranted when individuals are deficient, with dosage depending on serum concentrations of 25(OH)D. 

If you suffer from depression and/or live in a state that is cloudy most of the year (like Michigan), it is a great idea to have your serum vitamin D level checked.  If it turns out that you are deficient, your physician can prescribe the appropriate dosage of vitamin D in supplemental form, which may range from 1,000 IU per day to 50,000 IU per week.


Among nutritional deficiencies with potential relevance to psychiatric disorders, folate deficiency appears to be one of the most closely related to depression.  Folate is intimately linked to methylation and the synthesis of neurotransmitters in the central nervous system, such as serotonin; therefore, deficiency may cause changes in mood and brain function.  Some studies have found that individuals with low serum folate levels had higher ratings of depression and other mental health conditions than individuals with normal folate levels, despite therapy with ECT, antidepressants, and tryptophan.  Overall, research suggests that low serum folate levels may cause poorer response to some forms of antidepressant treatment.

Folate or folic acid is naturally present in a wide variety of foods, including vegetables (especially dark green leafy vegetables), fruits and fruit juices, nuts, beans, peas, seafood, eggs, dairy products, meat, poultry, and grains.  Spinach, liver, asparagus, and brussels sprouts are among the foods with the highest folate levels.  The RDA for folate is 400 mcg daily; increasing to 600 mcg during pregnancy and 500 mcg while breastfeeding; as folate plays a vital role in brain development and in preventing birth defects.

Folic acid is available in adult and child multivitamins, prenatal vitamins, supplements containing other B-complex vitamins, and supplements containing only folic acid.  Common doses range from 400 to 800 mcg in supplements for adults and 200 to 400 mcg in children’s multivitamins.  About 85% of supplemental folic acid, when taken with food, is bioavailable.  When consumed without food, nearly 100% of supplemental folic acid is bioavailable.  A physician may suggest folic acid supplementation during pregnancy and if a deficiency is detected. 

Vitamin B12

Vitamin B12 and other B vitamins play a role in producing brain chemicals that affect mood and other brain functions; therefore, low levels of B12 and other B vitamins, such as vitamin B6 and folate (see above), may be linked to depression.  The researchers of a 2015 review article, published in the Journal of Psychopharmacology, found substantial evidence that a decrease in serum vitamin B12 correlates with an increase in depression. They also stated that high vitamin B12 status may be associated with better treatment outcomes of depression.  The researchers suggest individuals with depression take a 1 mg B12 supplement daily.  However, more research overall is needed to fully understand the link between vitamin B12 and depression.

The RDA for vitamin B12 for adults is 2.4 mcg daily; increasing to 2.6 and 2.8 mcg daily for pregnant and breastfeeding women, respectively.   Vitamin B12 is naturally found in animal products, including fish, meat, poultry, eggs, milk, and milk products.  It is generally not present in plant foods, but fortified breakfast cereals are a readily available source of vitamin B12 with high bioavailability for vegetarians.  Some nutritional yeast products also contain vitamin B12, which is another great source for vegetarians and vegans.

Omega 3 Fatty Acids

The brain is one of the organs with the highest level of fats or lipids; and brain lipids, which are composed of fatty acids, are structural ingredients of membranes.  It has been estimated that gray matter contains 50% polyunsaturated fatty acids (about 33% belong to the omega-3 fatty acid family).  An important trend has been observed from recent studies, showing that lowering plasma cholesterol by diet and medications increases depression.  Among the significant factors involved are the quantity and ratio of omega-6 and omega-3 polyunsaturated fatty acids (PUFA) that affect serum lipids and alter cell membranes. It has been hypothesized that sufficient long chain PUFAs, especially DHA, may decrease the development of depression. 

The RDA for omega 3 fatty acids for teens and adults is 1.6 grams/day in males and 1.1 grams/day in females; which again increases to 1.4 grams and 1.3 grams during pregnancy and lactation.  Foods that contain omega 3 fatty acids include plant oils (flaxseed, soybean, and canola oils), chia seeds, walnuts, and cold-water fatty fish, such as salmon, mackerel, tuna, herring, and sardines.  If you are suffering from depressive episodes and/or are not eating enough of the above foods, adding an omega 3 supplement may be beneficial.   Omega 3s are present in several dietary supplements, including fish oil, krill oil, cod liver oil, and vegetarian products that contain algal oil.  A typical fish oil supplement provides about 1,000 mg fish oil, containing 180 mg EPA and 120 mg DHA, but doses vary widely.

Here is another great article, published in the Indian Journal of Psychiatry, that reviews even more nutrients that may play a role in depression and mood disorders.  There is a plethora of research suggesting that nutrition plays a vital role in the prevention and treatment of depression – and there is much more to be done!  However, if you are suffering with depression, the nutrients listed above may be a great place to start if you’re seeking alternative therapies.  As always, consult your physician to complete blood work and before starting on any dietary supplements.


Alpert, J. E., & Fava, M. (1997). Nutrition and depression: the role of folate. Nutrition Reviews55(5), 145-149.

Anglin, R. E., Samaan, Z., Walter, S. D., & McDonald, S. D. (2013). Vitamin D deficiency and depression in adults: systematic review and meta-analysis. The British journal of psychiatry202(2), 100-107.

Coppen, A., & Bolander-Gouaille, C. (2005). Treatment of depression: time to consider folic acid and vitamin B12. Journal of Psychopharmacology19(1), 59-65.

Fernandes de Abreu DA, Eyles D, Feron F. Vitamin D, a neuroimmunomodulator: implications for neurodegenerative and autoimmune diseases. Psychoneuroendocrinology 2009; 34 (suppl 1): S265–77.

Ginde AA, Liu MC, Camargo CA. Demographic differences and trends of vitamin D insufficiency in the US population, 1988–2004. Arch Intern Med 2009; 169: 626–32.

Langlois K, Greene-Finestone L, Little J, Hidiroglou N, Whiting S. Vitamin D Status of Canadians as Measured in the 2007 to 2009 Canadian Health Measures Survey. Health Reports 82-003-XPE: 8. Statistics Canada, 2010.

Miller, A. L. (2008). The methylation, neurotransmitter, and antioxidant connections between folate and depression. Alternative Medicine Review13(3).

Rao, T. S., Asha, M. R., Ramesh, B. N., & Rao, K. S. (2008). Understanding nutrition, depression and mental illnesses. Indian journal of psychiatry50(2), 77–82. doi:10.4103/0019-5545.42391

Reynolds, E. H., Preece, J. M., Bailey, J., & Coppen, A. (1970). Folate deficiency in depressive illness. The British Journal of Psychiatry117(538), 287-292.

Stoll AL, Severus WE, Freeman MP, Rueter S, Zboyan HA, Diamond E, et al. Omega 3 fatty acids in bipolar disorder: A preliminary double-blind, placebo-controlled trial. Arch Gen Psychiatry. 1999;56:407–12. 

Leave a Reply