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The interactions of Niacin, Vitamin B6, Tryptophan, Serotonin, and Melatonin

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Niacin, Vitamin B6, Tryptophan, Serotonin, and Melatonin are chemical compounds that play significant roles in our state of health and well-being. This article examines some key aspects of how these interact and affect our health.

Niacin (Vitamin B3) and Vitamin B6 are part of the B-Vitamin family, and are present in any B-Complex vitamin supplement. These vitamins exist in multiple forms that act a bit differently in the body depending on which form of the vitamin you get. They also have a relationship with the amino acid Tryptophan that is important. Tryptophan is the amino acid that is converted into 5-HTP and Serotonin, which is in turn converted into Melatonin. Serotonin is the neurotransmitter that affects mood and appetite, as well as other processes in the body. Melatonin is the hormone vital to facilitating sleep.

Vitamin B6 is a term used to refer to a group of naturally occurring pyridine derivatives represented by pyridoxine (pyridoxol), pyridoxal and pyridoxamine. Even though this vitamin exists in three forms, the term pyridoxine is currently used to cover the whole vitamin B6 group. Once digested, pyridoxine is converted rapidly to pyridoxal phosphate which acts as a co-enzyme in a wide variety of biochemical reactions. Supplements are now available which provide this more active co-enzyme metabolite of B6, which is valuable for those who desire a more active B6. However, the pyridoxal phosphate compound can be more dangerous to those prone to B6 overdose. B6 overdose (toxicity) is known to cause nervous system impairment, with symptoms such as numbness and tingling, motor difficulties, fatigue, and cardiovascular disturbances.

Niacin has been added to food since the 1930s to combat the disease Pellagra, caused by Niacin deficiency. Historically, Pellagra has appeared in areas with a heavy corn-based diet where people don’t mix the corn with ash/lime when cooking it, a cooking process which releases the niacin from its bound form. Niacin is found naturally in the husks of seeds such as brown rice, and is also synthesized by the body from Tryptophan using Vitamin B6. It takes approximately 60mg of Tryptophan to make 1mg of Niacin. The body uses the amino acid Tryptophan for a variety of things. It has been reported that about 7% of the Tryptophan one consumes is available to be converted to Serotonin and Niacin.

The biochemical pathways for those conversions work like this:

Tryptophan + Vitamin B6 –> Niacin

Tryptophan + Tryptophan Hydroxylase –> 5-HTP; 5-HTP + 5-HTP decarboxylase –> Serotonin; Serotonin eventually becomes Melatonin.

Now, there’s a switching mechanism present here that applies the body's wisdom about its priorities. Your body needs Niacin more urgently than it needs Serotonin. If you are Niacin deficient, then your body will convert more of the Tryptophan to Niacin, in order to get an adequate amount. (These two biosynthesis pathways compete, and the Niacin one is stronger). Therefore, if you’re not getting sufficient Niacin in your diet, you will often end up being deficient in Serotonin and Melatonin as your body uses up its available Tryptophan and Vitamin B6 to synthesize Niacin. You’ll become depressed and will have trouble sleeping, as your body sacrifices its Serotonin and Melatonin needs for the more critical Niacin need.

What are many common foods fortified with? Typically, it appears to be Niacinamide rather than the other form of Niacin. There are two forms of Niacin; one is Nicotinic Acid, and the other is Niacinamide. Since it is cheaper and more stable, the niacinamide form is the industry's preferred additive in cereals and flour. Unfortunately, Niacinamide does not trigger the switch in the pathways. It will stop you from getting Pellagra, yet it won’t flip the switch when the Niacin needs are met and allow for the Tryptophan to be directed toward Serotonin synthesis. Essentially, your body will use up the available Tryptophan for Niacin synthesis as if you still had a Niacin deficiency. Your body will carry on trying to convert Tryptophan into Niacin, and use it all up, leaving you with a somewhat lower amount of Serotonin (and also a decrease in available Vitamin B6, which is used up in the conversion process).

In order to help maintain healthy amounts of these compounds it is recommended that people ensure their diets have enough Niacin and Tryptophan. If not enough is absorbed in the diet, supplementing with Nicotinic Acid and L-Tryptophan would help restore balance. If you have enough Niacin then your body won't need extra Tryptophan and Vitamin B6 to synthesize Niacin, so making sure you have healthy Niacin levels is important in addressing any issues related to the other chemical compounds. Tryptophan and Niacin are also relatively safe supplements, not easy to overdose on. Tryptophan has been used safely and effectively to treat depression for decades, as it is much less likely than other treatments to cause undesirable side effects, and it does not promote Serotonin overload. Your body uses Tryptophan for what it needs, whereas other Serotonin regulating treatments (such as SSRI medications) can cause your system to accumulate excess Serotonin or inhibit natural Serotonin synthesis and regulation.

It is important to be conscious of how different nutrient supplements you consume interact with one another as well as how they may interact with herbs and allopathic medications. The body is designed to perform numerous balancing mechanisms to sustain its health, and what we provide the body as input can either support or disturb those natural efforts toward homeostasis.

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