How Capsaicin health benefits were found?
Do you ever think why the taste of chili peppers is spicy hot? It is due to the presence of capsaicin in a chili. Excessive intake of capsaicin causes burning and gastric irritation. But you may not believe that this heat-producing effect of capsaicin is effective in pain relief. These properties of capsaicin always attract researchers to do detail research on this phytochemical. The researchers had started their research long back. In 1876, researchers had first purified capsaicin and in 1919 the chemical structure of this herbal ingredient was derived.  After that, different research works continue to date to know more about this plant-derived active constituent.
Capsicum frutescens is a species of chili pepper, usually added in spicy recipes is our major dietary source of capsaicin. However, all plants belong to Capsicum genus that contains capsaicin as an active ingredient, except bell pepper (Capsicum annum). Capsaicin and other similar types of bioactive molecules group together and termed as capsaicinoids. The concentration of capsaicinoids differs from species to species.
Capsaicinoids concentration is relatively less in chili pepper i.e. 0.1 mg/g, red pepper contains little higher concentration 2.5 mg/g, whereas oleoresin red pepper contains 60 mg/g of capsaicinoids. Among different molecules present in capsaicinoids, capsaicin is present mainly in fruits, whereas other capsaicinoids found in leaves and stem of the plant. 
It has also been found that the consumption rate of capsicum species varies from region to region. The consumption rate is relatively low in India i.e. 2.5 g/person, in Mexico, it is quite high, i.e. 20g/person. The consumption rate in Thailand (5g/person) and in Saudi Arabia (15g/person) is moderate.
In capsicum fruits, placental tissue is surrounded by the seeds and concentration of capsaicin is high in this portion. Researchers noticed that capsaicin plays an important role in seed germination and gives protection against parasites. 
What is the Mode of action of Capsaicin health benefits?
Capsaicin follows a variety of mechanisms of actions to impart different health benefits by regulating Transient receptor potential vanilloid 1 receptor activity. The following are the different mechanisms of actions proposed for different therapeutic benefits of capsaicin.
- Atherosclerosis: Capsaicin improves endothelial function by activating endothelial nitric oxide synthesis, stimulating Liver X receptor alpha in a specific type of macrophage-like foam cells, distributing cholesterol.
- Diabetic vasculopathy: Capsaicin stimulates uncoupling protein 2 receptors and endothelial nitric oxide synthesis.
- Stroke: Stimulation of endothelial nitric oxide synthesis by capsaicin improve endothelial functioning.
- Angina: Capsaicin imparts a vasodilatory effect by improving the endothelium-dependent functioning of coronary arteries.
- Hypertension: Capsaicin stimulates endothelial nitric oxide synthesis and also reduces sodium retention in kidney tissue.
- Metabolic Syndrome: Activation of Transient receptor potential vanilloid 1 (TRPV1) via capsaicin enhances the activity of PPARgamma. Thus, capsaicin suppresses the production of different inflammatory mediators like IL-6, TNF-α, MCP-1, and cox-2, which exerts an anti-inflammatory effect on adipose tissue.
- Cardiac Hypertrophy: Activation of TRPV1 via capsaicin enhance the activity induces PPAR-delta activity.
- Fatty Liver: Capsaicin induced TRPV1 activation induces uncoupling protein 2 (UCP2) activity in hepatocytes. Besides, this phytochemical also decreases adipose inflammation and increases glucagon-like peptide-1 secretion
- Obesity: Capsaicin activates sympathetic functioning at brown fat and provides a thermogenesis effect. It controls vagus nerve signaling to control food craving. Capsaicin also has lipolysis activity.
- Gastric ulceration: Capsaicin reduces gastric acid secretion and make an alkaline environment and also improves gastric blood flow. 
Different Forms of Capsaicin
Supplementation of capsaicin is available in the market as a capsule, capsicum nasal sprays, and skin patch.
Capsaicin capsule: Individuals who do not like the raw form capsaicin or unable to tolerate the hot and spicy taste of capsaicin, they can intake Capsaicin capsule as a supplement.
Capsicum nasal sprays: This dosage form is recommended for treating non-allergic rhinitis and also providing symptomatic relief. Experts suggested that capsicum with 4 µg per puff dosing for thrice a day for three consecutive days is effective to control non-infectious, non-allergic, perennial rhinitis. 
Capsaicin patch: These patches are applied to the skin of the affected site. This patch usually recommended as an analgesic. Topical application of 8% capsaicin patch significantly decreases in post-herpetic neuralgia and post-traumatic neuropathic pain symptoms.
Capsaicin candy: This dosage form is effective to provide temporary relief from the pain associated with oral mucositis, which is a common side effect of chemotherapy or radiotherapy treatment.