There is a widespread agreement in the vegan community that, as a vegan, you need to take vitamin B12 supplements. It has been well researched and documented by notable vegan physicians and nutritionists that a vitamin B12 deficiency can lead to serious neurological problems such as schizophrenia, hallucinations and nervous disorders, as well as manifesting itself in the form of depression. However, there are supplements or vegan foods fortified with B12 so you can easily overcome this problem.
Another important thing to note about vitamin B12 is that is becomes more difficult for your body to assimilate it with age. Glands in your stomach secrete a protein referred to by researchers as intrinsic factor, which usually is necessary for your body to be able to absorb B12. However, this becomes more difficult for your body as you get older, and you may also find you develop digestive problems as your body secretes less hydrochloric acid with age, which is necessary to break down protein. Vitamin B12 usually comes bound to a protein, and so the lack of hydrochloric acid in your system also limits your B12 absorption.
Still, older people can get round the need for hydrochloric acid and the intrinsic factor by ingesting sufficient quantities of B12 supplements that are not bound to a protein and are chewable or dissolvable, as the B12 can therefore be absorbed through passive diffusion. Reliable sources suggest anyone, and not just vegans, over 50 should supplement B12, and it only requires a few lozenges per week if you don’t have any serious deficiencies or issues.
Another way to overcome depression with your diet is making sure you have a reasonable ratio of the short-chained fatty acids omega-3 and omega-6. Omega-6 can be found in vegan protein sources like seeds and nuts but when it comes to omega-3, it becomes a bit more complicated. There are significant amounts of omega-3 in some vegetables, mostly legumes and grains as well as vegetable oils, but omega-3 comes in three varieties. ALA or alpha-linolenic acid makes up most of the omega-3 found in plants, but your body must convert this into the other kinds of omega-3: DHA, or docosahexaenoic acid, and EPA (eicosapentaenoic acid) and you have a limited ability to do this. Further, amino acids that contain sulphur are essential for neural transmission, and require omega-3 fatty acids to metabolise them. This is a double problem for vegans as both the amino acids and omega-3 are found primarily in eggs and meat.
If you are a vegan experiencing depression symptoms, consult your dietician or, better yet, your doctor.