That being said, I've suspected for some time that there may be a link between vegetarianism and depression, and according to this study, there is. Vegetarians are 2-3 times more likely than meat eaters to suffer from depression, anxiety, eating disorders, and somatoform disorders and syndromes. In addition, this other study contends that Vitamin B12 deficiency (common among vegetarians) can lead to a lack of response to conventional antidepressants. This actually makes perfect sense to me, and here is why:
We are meant to eat meat
That's right, we were designed to eat meat through millions of years of evolution. The archaeological record shows that early humans ate mostly other animals, and when early 19th century explorer Weston Price went looking for vegetarians in native populations through the south sea islands and Florida natives, he found none. Every native population he studied ate meat, were in good health and had perfect teeth (perfect dental arches and no cavities).
There is also plenty of evidence of our dependence of meat in our own biology and biochemistry. If we were meant to eat only vegetables, we'd have the digestive system of a cow, with four stomachs and the ability to ferment cellulose to break down plant material. There are also a number of essential nutrients that our bodies cannot make and can only be found in animal sources (e.g. Vitamin B12).
Meat contains certain nutrients essential to adequate brain functioning
Our brains are made mostly of fats and cholesterol. In fact, the dry mass of myelin is about 70-85% fats and 15-30% protein. Saturated fatty acids also make up the phospholipid bilayers that make up our neurons, axons, and dendrites. In addition, certain animal nutrients play a key role in neurotransmitter support, the lack of which could trigger neurotransmitter imbalances resulting in a range of psychological and psychiatric disorders.
What to do?
As I said, I admire the sacrifices that vegetarians make to uphold their principles. Thankfully, in today's modern world, you can continue your vegetarian diet as long as you take appropriate supplements to make up for your dietary deficiencies. The following supplement links should help vegetarians obtain the brain-healthy nutrition they wouldn't otherwise get.
Phosphatidylserine, or PS for short, is a phospholipid component kept on the inside of the phospholipid bilayer. Many of the reviewers on Amazon for this product report improvement in sleep and memory while reducing anxiety.
While some vegetable sources contain PS, it is found in much higher concentration in meats and animal innards. For example, a carrot contains 2 mg/100g, while a chicken leg contains 134 mg/100g. Fish like mackerel and herring also are rich in PS, with mackerel containing 480 mg/100g. Most PS (like the one linked to here) is derived from soy lecithin rather than cow brains, althought it's probably from GMO soy. If you prefer a non-GMO option, try getting your PS from these Non-GMO Sunflower Seed Lecithin softgels. Of course, while these are indeed non-GMO, they do come in gelatin softgels, which some vegetarians might frown upon.
Choline (Alpha GPC)
Choline is an essential nutrient, often grouped with B-vitamins. It is used in the brain to form two classes of phospholipids abundant in cellular membranes. It is also the precursor to the neurotransmitter acetylcholine (ACh). This neurotransmitter is used by the cholinergic system in the CNS, which tends to cause anti-excitatory actions and has an important role in decision-making and sustaining attention. Damage to the cholinergic system has been shown to be associated with memory deficits observed in Alzheimer's disease. In addition, choline deficits can result in headaches, cluster headaches and migraines.
Choline is especially important during pregnancy as it is used as a substrate in building cellular membranes in the rapidly-developing embryo. In addition, various forms of choline are abundant in breast milk in order to support the infant's cellular and brain development. It is, therefore, imperative for pregnant and breastfeeding women to make sure they are getting enough choline from their diet or to supplement accordingly.
Eggs yolks have some of the richest sources of choline, followed by beef liver and kidneys, and fish caviar.
Vitamin B-12 (and others)
B-vitamins are found in greater concentration in meats, although some B-vitamins are found in some vegetable sources as well. Vitamin B-12 is the exception here, as it is not found in vegetables at all. It must be synthesized from bacteria or extracted from animal sources. Deficiency in Vitamin B-12 can lead to peripheral neuropathy (paralysis), memory loss, and other cognitive deficits. Similarly, Vitamin B-6, is used to convert 5-HTP into serotonin and melatonin. It is also used in the synthesis of dopamine, norepinephrine, and epinephrine. Not surprisingly, Vitamin B-6 deficiency is linked with depression.
B-vitamin deficiencies have all kinds of exciting neurological symptoms, such as:
- B-1 Deficiency - Emotional disturbance, impaired senses, weakness, Korsakoff's syndrome (dementia, amnesia, false memories), heart failure and death in severe cases.
- B-3 Deficiency - Aggression, insomnia, weakness, confusion, dementia and death in severe cases
- B-6 Deficiency - Depression
- B-12 Deficiency - peripheral neuropathy, memory loss, macrocytic anemia, mania and psychosis.
Creatine is not an essential nutrient per se, since our bodies make it from L-arginine, glycine and L-methionine, however, it is a nutrient also found in red meat and studies have found that vegetarians have a significantly lower amount of creatine in their tissues.
Creatine plays a pivotal role in brain energy balance through its action on the ATP-ADP cycle. This study found that oral creatine supplementation resulted in an increase in intelligence and working memory in vegetarians.
Essential aminoacids are those we must acquire through our diet since they are not made by the human body. The essential aminoacids are phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine, and histidine. While these are all important, of special note for brain health are phenylalanine and tryptophan.
Phenylalanine is naturally found in mammalian breast milk, and is a precursor to neurotransmitters dopamine and norepinephrine. As we all know, dopamine is an important neurotransmitter in the signaling pathways for the pleasure and reward centers of the brain. One of the main symptoms of dopamine deficiency is depression, but it can also carry along other symptoms such as oversleeping, low libido, rapd weight gain, and parkinson's disease.
Tryptophan, mainly found in eggs, cod, cheese, and meats, is the biochemical precursor to serotonin, another important neurotransmitter. Low levels of serotonin are linked to depression and anxiety and SSRI drugs like Prozac and Zoloft target depression by boosting serotonin levels through blocking its re-uptake into the secreting axon. A metabolite of Tryptophan, 5-HTP is also sold as a dietary supplement and is believed to be more effective as a serotonin precursor than ingestion of tryptophan alone since it readily crosses the blood-brain barrier.
So there you have it. If you are a Vegan or a Vegetarian, and have been feeling blue lately, it could very well be that your diet is lacking in some essential happiness-inducing nutrients. Try supplementation with the above and see if your mood changes for the better. One word of caution, though, is that if you're taking a supplement that directly increases the amount of a neurotransmitter that's already being targeted by your prescription medication, take it slow at first and see how you react to it. If you're already on pharmaceutical antidepressants, it would be a very good idea to consult with your doctor before taking any nutritional supplements.