Turmeric is scientifically called Curcuma longa. It is a rhizome, kind of herb of the ginger family. Turmeric is bitter in taste with a slight evocative fragrance of orange and ginger. It is one of the major ingredients of the Indian curries. It is derived from the root of the plant and has a brown upper covering and orange colored flesh. It was also known as “Indian saffron” because of its orange-yellow color. It has been used for quite a long time for medicinal purposes.
A few things about turmeric
(if you know this, please skip this section)
Turmeric is generally habituated in tropical regions of India like Tamilnadu because it requires 20-30 ®C temperature range for growth and an ample amount of rainfall. The nutritive quality of turmeric is due to its constituents. Turmeric has Manganese, Iron , Vitamin B6 , Fiber, copper, potassium, etc. Thus the nutritional value of turmeric is quite high. Turmeric is being used for the treatment of inflammatory and bowel diseases for quite a long time. Turmeric is used as an ingredient in curry, as a healing agent and used for textile dyeing purposes.
Curcumin is the most active constituent of turmeric (50-60%) and it has been shown to exhibits anti-oxidant and anti-inflammatory properties. Turmeric has been found to exhibit many therapeutic properties and hence is being used for centuries in the traditional Indian or Ayurvedic medicines. Turmeric has been discovered to have anti-cancerous properties. Also turmeric is being used for the treatment of inflammatory diseases such as tendinitis, liver cirrhosis, Alzheimer’s disease and many other digestive and blood related problems. It has other significant properties like anti-bacterial, liver and kidney protective nature, blood clot suppressing property and also helps in the prevention of heart attack and hypoglycemia.
What is Bioavailability of turmeric?
Many studies have shown that turmeric is safe even at higher dosage. The efficacy of turmeric has also been proved by many clinical studies. This efficacy and safety makes turmeric a potent compound for the treatment of wide range of human diseases. Besides all these reasons turmeric has not yet been officially declared as a therapeutic agent and the major reason behind this is the relative low bioavailability of turmeric.
The reason behind the low availability of any agent within the body is its low indwelling activity, inactivity of metabolic compound or its rapid removal from the body. Studies rule out the first option of low intrinsic activity of turmeric. Turmeric’s efficacy and strong activity has helped in its establishment as a therapeutic component in the treatment of many ailments. However studies regarding absorption, transportation, assimilation and elimination of curcumin have revealed low absorption and its rapid metabolism which leads to relatively low bio-availability of turmeric.
Why turmeric has low bioavailability?
The major factors that affect the bio-availability of turmeric are sorted below
- Serum concentration
- Tissue distributions
- Rapid metabolism
- Short half-life
One of the major considerations in the study of curcumin involves low serum levels. The very first study reported related to the uptake, assimilation and excretion of curcumin was by Whalstrom and Blennow in 1978 using rats. In their studies they showed poor absorption of curcumin from the gut. When 1g/kg of curcumin was administered orally in the rats only negligible amount of curcumin was found in their blood plasma. Again in 1980, Ravindranath et al showed that when only 400 mg of curcumin was ingested by the rat, no trace of curcumin was found in the heart blood while only a small trace was found in the portal blood within 15 min to 24 hours of administration. In a very recent study Yang et al showed that administration of 10 mg/kg of curcumin results in only 0.36 µg/ml of curcumin in the blood serum. These studies show that the route of administration has a role to play in the metabolism of turmeric. Also the absorption of curcumin is a major factor responsible for low bio-availability of turmeric.
Ingestion and distribution of curcumin to various tissues of body is actively responsible for its bio-availability. But this topic has not got the attention of the scientists studying about the bio-availability of turmeric. Studies of Ravindranath revealed that only a trace amount of curcumin was present in the stomach and intestine. Many other studies in this filed have shown that even higher dosage of curcumin does not increase the absorption of curcumin as well as itsdistributions.
Liver is the major organ involved in the metabolism of curcumin. After absorption curcumin undergoes conjugations like sulfation and glucuronidation. When metabolized in liver, the major metabolic product of curcumin are glucuronides of Tetrahydrocurcumin (THC) and Hexahydrocurcumin (HHC). Most of the studies have shown that these metabolites are actually less active as compared to Curcumin itself. So when metabolized the activity of curcumin seems to be lost.
Systemic excretion of curcumin from the body is also a major factor responsible for its activity. Studies by Whalstrom and Blennow showed that when 1g/kg curcumin was ingested by the rat, around 75% of the curcumin was excreted and only a trace amount was found in the urine. Thus low half-life of curcumin decreases its activity in the body. There is not much information about half-life of curcumin has an important role to play in its biological activity. But still it is a topic to be concentrated on in the future.
How can turmeric’s Low bioavailability be addressed?
These are the problems causing the low availability of curcumin. But some of these problems can be solved using various ways listed below
- Liposomes, phospholipids and micelles
Adjuvants generally improve the bio-availability of curcumin by blocking its metabolic pathway. Shoba et al combined Piperine which has the property to inhibit glucuronidation in the liver and intestine, then administered it in the rats and healthy humans. In rats when 2g/kg of only curcumin was administered, 1.35 µg/ml of curcumin was found in the blood serum. But when it was administered in combination with piperine (20mg/kg), the serum level was increased, time required to reach the peak level also increased, elimination and half-life were decreased reasonably. Bio-availability of curcumin was increased up to 154%. In humans when 2g curcumin was administered, the serum concentration was found to be either very low or were undetectable. Curcumin combined with piperine introduced in the humans, resulted in 2000% increased bio-availability. Thus the effect of introduction of piperine is much more significant in humans than in rats. The effect of piperine on tissue uptake has also been shown in many studies. Piperine is one such agent used. There are many other adjuvants that can be used to serve this purpose like genistein. Thus all these studies have shown that curcumin activity can be modulated both at cellular and organismic levels.
Recently nanoparticles are being used as targeted and triggered drug delivery mechanisms. These nanoparticles have also emerged as solutions for the bio-availability of certain therapeutic agents. Curcumin is hydrophobic in nature and the solubility in aqueous solutions arises a problem. Nanoparticles can be used to serve such purposes in a recent study by Bish et al polymer based nanoparticles with size less than 100 nm have been synthesized named “nanocurcumin”. Nanocurcumin has been found to have the similar biological activity as that of free curcumin. It has the same anti-oxidant and anti-inflammatory effects as the free curcumin has. There haven’t been much studies related to nanocurcumin increasing the efficacy of curcumin. But solid lipid nanoparticles when loaded with curcuminoids
are found to be stable and release curcumin for 12 hours. Research work is going on to study the role of nanoparticles in increasing the efficacy of curcumin.
Phospholipids, micelles and liposomes
Liposomes are nice drug delivery systems as they have the ability to carry both hydrophobic as well as hydrophilic molecules. Li et al studies revealed that liposomal curcumin has anti-tumor property for human pancreatic tumor cells. It prevents the growth of pancreatic tumor cells and also has the anti-angiogenic properties. Evaluation of exact efficacy of liposomal curcumin over the free curcumin is still under process. The liposomal carrier has more loading capacity of curcumin and also plays a great role in increasing the bio-availability of curcumin.
Micelles and phospholipid complexes increase the absorption of drugs from the gastrointestinal tracts resulting in higher blood plasma concentration and lower elimination and thus increasing the bioavailability. Many studies suggest that the absorption of curcumin increases from 47% to 56% when it is present in the micelles. Ma et al studied that the half-life of polymeric micellar curcumin is 60 folds higher than free curcumin. In a study by Liu et al, curcumin (100 mg/kg) and curcumin-phospholipid complex (corresponding to 100 mg/kg) were administered in rats. Curcumin-phospholipid complex yielded 600 ng/ml of serum curcumin level while only 267 ng/ml in case of free curcumin. Also the half-life increases 1.5 folds in case of curcumin-phospholipid complex.
Easy ways to make turmeric bioavailable in body
The main reason behind the non-availability of curcumin in body for regular users is due to its low solubility in water. But there are other ways by which one can take curcumin without its solubility coming in its way.
Black Pepper: One can use the mixture of curcumin with pepper. Bioperine is an extract from the fruit of Piper nigrum (black pepper). It is one of the best ways to take turmeric by mixing it with Bioperine. Including black pepper in your diet or taking it with turmeric should help in absorption of turmeric in body.
Mixing with fats: Also mixing curcumin with fat will do. Curcumin can be mixed with coconut oil, flaxseed oil, olive oil etc.
Mixing with Quercetin: Curcumin can be taken as a mixture of curcumin and quercetin. Quercetin is flavonoid and is found in many plants and foods such as apple, red grapes, onion, citrus fruit etc. Quercetin inhibits the sulfotransferase enzyme that inactivates curcumin. Also bicurcumax is available which has curcumin dissolved in fat of 10-15% by weight.
Using Silibinin : This is the major active constituent of silymarin, a standardized extract of the milk thistle seeds. It is also know to increase the bioavailability of turmeric. Well, I am not sure how to use it this in daily life as of now.
Heated water: It can be taken with water too only if its solubility is enhanced (else it generally has to be taken with fats as part of food). Probably the bioavailability of curcumin can also be enhanced with heat because heat increases the solubility of curcumin in water. Studies have shown that boiling turmeric in water for 10 min increases its solubility 12 fold (remember its solubility, not absorption). The verdict is still not out on how much it impacts the absorption. But this may be the reason why taking turmeric with warm milk (golden milk!) is considered great!
Special tablets: Curcumin tablets are also available. These (one has to be careful as not all tablets may have this poperty, look for it before buying) are encapsulated and have a specific property. Much of the bio-activity of curcumin is lost because of the formation of curcumin glucorinide and curcumin sulfate which occurs in the acidic environment inside the stomach. So these capsules make sure of this that they dissolve only in alkaline environment and remain intact in acidic condition. So these capsules dissolve and the curcumin remains come out of the capsule in the intestine where its solublisation is not a problem.
As detailed above all these problems causing low bio-availability of curcumin can thus be overcome by the above given strategies, some of them I know are very tech. but others such as black pepper and with fat are easy to follow. As curcumin is very important in our day to day life as well as it has found its role in the medical field too, it needs to be modulated for proper utilization. The above explained modulation can thus overcome the situation of low bio-availability of curcumin.