We hear so much about serotonin levels and sadness, happiness, depression… but what exactly is serotonin? How does it work? What about the serotonin theory of depression?
Let’s dive deep into some serotonin research and get on the serotonin transporter to understand what serotonin activity is all about.
What is serotonin activity?
Serotonin is an amino acid that works as a hormone and as a neurotransmitter. That means it carries messages between nervous cells in your brain and to all parts of your body. Serotonin has many functions. It’s involved in learning, cognition, memory and reward systems; it’s also considered to be a natural mood stabilizer. Some mood disorders occur with lowered serotonin activity. Serotonin is produced in the gut and most of the serotonin found in our bodies lives there. Serotonin is essential for healthy digestion.
The serotonin system helps balance many body functions. Let’s look at how serotonin works, and at the chemical imbalance theory. Because serotonin deficiency has been linked to mental health disorders, we’ll also look at the serotonin theory of depression.
Serotonin receptors and the gut
Serotonin regulates digestion. Serotonin tells our brains we’ve eaten enough so we stop eating and don’t get full. When we consume an irritant, the serotonin levels rise so these healthy volunteers will speed up digestion to get rid of the toxic component as soon as possible. Our general health is determined by our gut health. There is consistent evidence that the gut microbiome regulates how the body functions and determines which nutrients and toxics our body either absorbs or rejects. This is the basis for the low serotonin hypothesis of depression, or how depression is caused.
At the same time, serotonin regulates our nausea and vomiting reflexes; therefore, medication to control these problems targets specific serotonin brain receptors. The chemical imbalance theory suggests that when there are chemical imbalances, lower serotonin concentrations appear. Lowering serotonin levels can cause serotonin abnormalities that could trigger risk factors for mental illness.
Serotonin levels and mood/sleep
Due to the effect serotonin has on the brain, serotonin is best known for the role it plays in mood and sleep. At normal levels in the brain, serotonin causes that ‘feel-good’ sensation. That’s why it’s believed that low levels of serotonin and depression could go hand in hand. Treating depression, however, is much more complicated than that. Low serotonin levels might help with a depressive state but there’s usually more than low serotonin levels behind a major depressive disorder.
The involvement of serotonin in the sleep cycle is still being studied. The right serotonin levels are important to regulate sleep, as are the levels of dopamine and melatonin.
Your body needs serotonin to produce melatonin, which is critical to the sleep cycle. Low serotonin levels will manifest as difficulty sleeping. Serotonin receptors are placed all throughout our brain and body. The areas of the brain that regulate sleep cycles are full of serotonin receptors. Sleep problems, such as insomnia, are common in those who have difficulty regulating their serotonin levels – such as depressed patients.
The serotonin effect on mood is the reason it’s used for treating depression, anxiety and other mood disorders. SSRI antidepressant treatment stands for ‘selective serotonin reuptake inhibitors’.
Serotonin levels, blood clotting and bone density
When we suffer tissue damage, serotonin is released to thicken the arterial walls. The blood flow slows down and this helps the healing process. It’s your platelets that release serotonin to help with the healing.
Research has shown that bone density might be affected by serotonin levels. High serotonin levels in the gut are related to low bone density and can lead to osteoporosis later on in life. SSRI medications used to treat clinical depression have been linked to low bone density. If you’re worried about taking SSRIs or you’re thinking about future treatment approaches, talk to your healthcare provider, who can best help you keep your mental health at its optimal level.
Serotonin levels and sexual activity
I’m not going to say that unbalanced serotonin levels cause depression, because it’s not true. I’m afraid I have to say, though, that they’re responsible for poor sexual activity, drive and performance. Hypoactive Sexual Desire Disorder is characterized by an increase in serotonin. Increasing serotonin will cause a decrease in dopamine. Dopamine is linked to love and happiness. Dopamine and oxytocin are key to a sexually thriving body.
If you’re thinking about how to increase serotonin levels, you must bear this in mind. Serotonin needs to be balanced. A high amount of it won’t improve your sex drive.
Serotonin levels and depression
A lot has been said to link to serotonin and depression but mental health is much more complex than an ‘increase serotonin, reduce serotonin’ kind of button to induce depression. To say that depression is caused by a maladjustment of serotonin levels does not show an understanding of the complexity of the human being, especially the brain.
Research has shown that the serotonin hypothesis of depression hasn’t been empirically substantiated. It’s been quite difficult to relate mood states to changes in serotonin activity. Normal changes in body temperature will cause serotonin levels to fluctuate. The serotonin theory is 50 years old and it’s now believed to have been formulated to enable pharmaceutical companies to market selective serotonin reuptake inhibitors (SSRIs) to a gullible public.
When depression hits a loved one it affects the whole family. A ‘quick fix’ for something so daunting might seem like the best option. SSRIs have been widely used for many decades. Some people might benefit from them, especially in the first stages of depression treatment; however, they tend to hide the symptoms instead of resolving depression and give depressed patients and their relatives a false sense of improvement.
Depression is not caused by low serotonin levels
Depression is caused by many different factors. Personal and family history play an important role in depression risk factors. Research into serotonin levels and depression has shown that the best evidence of the role that serotonin plays in depression has a lot to do with the amino acid necessary to produce it: tryptophan.
‘In healthy participants with no risk factors for depression, tryptophan depletion does not produce clinically significant changes in mood; however, recovered depressed patients free of medication can show brief, clinically relevant, depressive symptomatology. Interestingly, the same is true of recovered depressed patients undergoing catecholamine depletion with alpha-methyl-para-tyrosine.
‘Overall, this evidence suggests that impairing serotonin function can cause clinical depression in some circumstances, but is neither necessary nor sufficient. In addition, the depressogenic effects of tryptophan depletion are much more apparent in people who have experienced prior episodes of depression than in those simply at high risk of illness, for example by virtue of a strong family history’.
In other words, some depressed patients will have low serotonin levels and others might not; there will be people with low serotonin levels who might not be depressed at all.
What causes serotonin levels to drop?
There are two main reasons for low levels of serotonin:
- The body isn’t producing enough serotonin
- The body isn’t using the serotonin it produces effectively.
The reason why your body doesn’t produce enough serotonin has a lot to do with nutritional and vitamin deficiencies. Tryptophan, the essential amino acid involved in serotonin production, can only be obtained through diet. Low serotonin has also been related to low levels of vitamins D and B6.
When you produce enough serotonin but your body isn’t using it effectively, the problem can be linked to the serotonin receptors in your brain. You might also have the right number of receptors but they might not be functioning well; therefore, although you’re producing good amounts of serotonin, your brain isn’t receiving the right amount.
How can I restore my serotonin levels?
Low serotonin has been associated with low levels of vitamin D and B6 and with low tryptophan.
Foods high in tryptophan are: spirulina; cheese; chicken; soybeans; lentils; nuts; bananas; and spinach. To increase your B6 levels you can increase your intake of tuna and salmon. Be mindful of mercury levels in big fish. Mackerel and sardines are also good sources of vitamins and omega-3 amino acids. Beef liver, turkey and other poultry have a high vitamin B6 content.
If these foods are not an option for you, you can increase your consumption of leafy greens, oats, chickpeas and pulses and citric fruits, such as oranges, tangerines, or grapefruits. Bananas and papaya will also help with serotonin production.
Vitamin D is best absorbed by the skin. Spending time outside on a regular basis can bring your vitamin D levels right up. If your levels of serotonin are appropriate but your brain is unable to process it, touch therapy can greatly help with this.
Have a pleasurable massage or even get a mani or pedicure. Activities that involve touching your skin with intention, love and care will boost your serotonin and dopamine levels. Mindfulness and positive thinking can also help greatly in bringing the levels up.
Although more research is been carried out as you read this, psilocybin micro-dosing is proving to have beneficial effects in treating depressive disorders. Psilocybin is the active component in ‘magic mushrooms’ and the findings are very promising, compared with SSRIs, due to psilocybin’s rapid effects and very few to no adverse side effects.
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