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Turmeric (Curcuma longa) is a perennial herbaceous plant of the ginger family (Zingiberaceae) that grows in India and other countries in Southeast Asia. Turmeric has been used in traditional Indian and Chinese medicines for thousands of years and is believed to be one of the most powerful disease-fighting herbs on the planet1.

The dried root of turmeric is ground into a distinctive yellow powder, hence the name golden spice, and this ground turmeric is the main component of the curry powder commonly used in Asian cuisine. Turmeric has more than 300 biologically active (bioactive) compounds.

What are bioactive compounds?

Bioactive compounds are molecules that can exhibit therapeutic potential with influence on energy intake, while reducing proinflammatory states, oxidative stress, and metabolic disorders2. Consuming foods rich in bioactive compounds with high antioxidant activity, such as vitamins and phytochemicals, and mainly phenolic compounds (flavonoids, carotenoids, etc.), has been associated with many benefits for human health and with a reduced risk of several diseases, namely chronic and lifestyle diseases such as cancer, stroke, heart disease, and diabetes2.

What are phenolic compounds?

Phenolic compounds are plant chemicals found in most plant tissues, including fruits and vegetables, characterized by having at least one phenol unit in their structure. According to the chemical structure, phenolic compounds can be divided into different subgroups, such as phenolic acids, flavonoids, lignans, tannins, stilbenes, coumarins, quinones, and curcuminoids3.

Curcuminoids

Curcuminoids are the main polyphenol (molecules that have multiples of phenol units in their structure) constituents of turmeric and are constituted by three main chemical components4:

  • Curcumin (75–80%) (the key-colored compound)
  • Demethoxycurcumin (15–20%)
  • Bisdemethoxycurcumin (3–5%) 

Curcumin

Curcumin is the main bioactive principle of turmeric, constituting the basis for the medicinal properties of this plant. Curcumin is also a yellow/orange pigment often used as food colorant1,4

There are thousands of published scientific articles providing turmeric and especially curcumin benefits, many of them for cancer treatment. Research on curcumin has proven its effectiveness in treating and preventing many health issues, including inflammation, liver and heart disease, arthritis, metabolic syndrome, obesity, neurodegenerative diseases and several cancers5.

Curcumin has shown impressive biological activities: antioxidant, anti-inflammatory, antimicrobial, antiviral, anti-infectious, hepatoprotective, thrombo-suppressive, cardio protective, anti-arthritic, chemo preventive and anti-carcinogenic5,6. The anti-cancer potential is the most widely described, and curcumin is able to suppress both initiation and progression in stages of cancer, and its activity is due to negative regulation of inflammatory cytokines, transcription factors, protein kinases, reactive oxygen species (ROS) and oncogenes6.

Why is curcumin so efficient?

Curcumin is a phytochemical. Phytochemical is a broad term that literally means plant (phyto) chemical and refers to a wide variety of compounds that occur naturally in plants7.

Phytochemicals are non-nutrient bioactive components that are primarily responsible for scavenging toxic radicals after oxidative stress by generating antioxidants. Free radicals from oxidative stress are known to be involved in the development of the systemic inflammatory response, which if not addressed can result in chronic inflammation, the main cause of most chronic diseases8,9.

Since phytochemicals like curcumin have a great antioxidant potential, they play a significant role in the prevention of harmful free radical activity. They contribute to reduced inflammation and have been linked to lower incidence of degenerative diseases and lower mortality average in humans9. This happens because most health conditions develop in a person’s body from chronic inflammation, thus reducing inflammation will decrease the occurrence of such conditions10.

How does curcumin work for cancer treatment?

Curcumin exhibits anticancer activity by targeting different cell signaling pathways including growth factors, cytokines, transcription factors, and genes modulating cellular proliferation and apoptosis5.

The regulation of apoptotic proteins is of enormous importance, since they are responsible for normal programmed cell death, which helps eliminate abnormal cells from the body – an essential process in cancer treatment. What’s interesting is that curcumin can distinguish between an abnormal cell and a normal cell – it prevents the replication and growth of abnormal cells. 

Curcumin consumption will contribute to reduced inflammation and to managing and controlling abnormal cell growth and proliferation. However, curcumin anticancer effects go way beyond these effects, and target many pathways11:

Benefits of Curcumin for Healing
  • Inflammation (powerful anti-inflammatory, and cancer stems from chronic inflammation)
  • Angiogenesis (suppress the formation of new blood vessels)
  • Invasion 
  • Growth/proliferation (inhibit cancer cell proliferation)
  • Cytotoxicity (directly killing cancer cells)
  • Apoptosis (programmed cell death)
  • Oncogenic metabolism/metabolic reprogramming (changing the metabolism of cancer cells)
  • Lactogenesis (excess lactate production)
  • pH balance (Acid/base balance)
  • Alterations in the tumor microenvironment (changes in the environment surrounding tumors)
  • Cell survival (increased survival of healthy cells)
  • Tumor escape
  • Metastasis (reduce incidence of metastasis)
  • Immunomodulation (modulation of the immune system)
  • Hormones
  • Epigenetics 
  • Gut microbiome
  • Cancer stem cells (kill cancer stem cells)

Moreover, curcumin helps increase chemotherapy and radiation sensitivity, it helps to overcome treatment resistance, and it is an excellent adjuvant therapy to ANY cancer treatment program11.

The fact that curcumin can selectively target cancer stem cells while having little to no toxicity for normal stem cells is of paramount importance, since normal stem cells are essential for tissue regeneration and longevity. That is also believed to be one of the reasons why curcumin is notably effective against multi-drug resistant cancer – most likely because it neutralizes cancer stem cells.

Poor bioavailability of curcumin

An issue often reported is the low efficacy of curcumin in certain settings. The biological beneficial effects of curcumin have been proven; hence the problem with its efficacy is related with the form of delivery, in this case with the low oral bioavailability12. Curcumin shows poor bioavailability when taken orally, due to low absorption, rapid metabolism, and systemic elimination. Unfortunately, these factors affect and limit its efficacy in the treatment of several diseases5.

The low oral bioavailability of curcumin results from several factors, mainly related to gut health12

  • Low solubility
  • Gut integrity
  • Gut microbiome
  • Poor GI absorption
  • Hyper-metabolism (breakdown) of the curcumin compound
  • Rapid elimination of curcumin from the body
  • Poor systemic delivery of curcumin

This happens because in today’s world most people suffer from gut issues which won’t allow proper delivery of curcumin, and this happens also with many other nutrients. 

How to overcome poor curcumin bioavailability?

Intravenous curcumin is the only way to bypass the gut, and the best way to deliver the full healing, anti-cancer potential of curcumin12.

However, for those who do not have access to intravenous curcumin, taking it orally is still a great option and will provide many of the healing benefits of curcumin, especially when its bioavailability is enhanced with other super foods.

How to improve oral bioavailability of curcumin

Some factors can help increase gut absorption of curcumin and its oral bioavailability12:

  • Liposomal preparations (improve the absorption)
  • Nano formulations (improve the solubility)
  • Piperine, silibinin, quercetin (have their own anti-cancer benefits and inhibit the metabolism breakdown of curcumin, increasing systemic delivery)

For example, piperine increases the bioavailability of curcumin by 2000%13! This is an enormous increase! 

Is it sufficient though? 

Let’s check the facts:

  • 500mg of curcumin 
  • Bioavailability of oral curcumin is 1%
  • 1% of 500mg = 5mg
  • Piperine increases bioavailability by 2,000%
  • 2,000% of 5mg = 105mg

In sum, with the normal 500mg of curcumin (a normal over-the-counter supplement) only 5mg is available for systemic effects; adding piperine, 105mg become available. This is a great increase, but still not enough to reach the full anti-cancer potential of curcumin. 

Although you can and should add curcumin (with some added piperine) to your meals, or take a curcumin supplement that ensures increased bioavailability, keep in mind that intravenous delivery of curcumin is the only way to achieve the full healing potential of curcumin, not just for cancer treatment, but for other diseases and overall health12.

Safety and side effects

Curcumin is generally well tolerated even in high doses and “generally recognized as safe” (GRAS) as a food ingredient by the U.S. Food and Drug Administration. Although curcumin side effects are usually minimal, some gastrointestinal side effects such as nausea, diarrhea and yellow stool, allergic reactions and headaches have been reported5,14.

REFERENCES

  1. Unlu A, Nayir E, Dogukan Kalenderoglu M, Kirca O, Ozdogan M. Curcumin (Turmeric) and cancer. J BUON. 2016 Sept-Oct;21(5):1050-1060. PMID: 27837604.
  2. Santos DI, Saraiva JM, Vicente AA, Moldão-Martins M. 2 – Methods for determining bioavailability and bioaccessibility of bioactive compounds and nutrients. Innovative Thermal and Non-Thermal Processing, Bioaccessibility and Bioavailability of Nutrients and Bioactive Compounds. In Woodhead Publishing Series in Food Science, Technology and Nutrition. Woodhead Publishing; 2019. 23-54p. https://doi.org/10.1016/B978-0-12-814174-8.00002-0.
  3. Gan R, Chan C, Yang Q, Li H, Zhang D, Ge Y, Gunaratne A, Ge J, Corke H. 9 – Bioactive compounds and beneficial functions of sprouted grains. Sprouted Grains. AACC International Press; 2019. 191-246p. https://doi.org/10.1016/B978-0-12-811525-1.00009-9.
  4. Hassanzadeh K, Buccarello L, Dragotto J, Mohammadi A, Corbo M, Feligioni M. Obstacles against the Marketing of Curcumin as a Drug. Int J Mol Sci. 2020 Sep 10;21(18):6619. doi: 10.3390/ijms21186619. PMID: 32927725; PMCID: PMC7554750.
  5. Giordano A, Tommonaro G. Curcumin and Cancer. Nutrients. 2019 Oct 5;11(10):2376. doi: 10.3390/nu11102376. PMID: 31590362; PMCID: PMC6835707.
  6. Qadir MI, Naqvi ST, Muhammad SA. Curcumin: a Polyphenol with Molecular Targets for Cancer Control. Asian Pac J Cancer Prev. 2016;17(6):2735-9. PMID: 27356682.
  7. Huang Y, Di Xiao, Burton-Freeman BM, Edirisinghe I. Chemical Changes of Bioactive Phytochemicals during Thermal Processing. Reference Module in Food Science. Elsevier; 2016. https://doi.org/10.1016/B978-0-08-100596-5.03055-9.
  8. Mohamed HI, El-Beltagi HS, Jain SM, Al-Khayri JM. Chapter 18 – Date palm (Phoenix dactylifera L.) secondary metabolites: Bioactivity and pharmaceutical potential. Phytomedicine. Academic Press; 2021. 483-531p. https://doi.org/10.1016/B978-0-12-824109-7.00018-2.
  9. Closa D, Folch-Puy E. Oxygen free radicals and the systemic inflammatory response. IUBMB Life. 2004 Apr;56(4):185-91. doi: 10.1080/15216540410001701642. PMID: 15230345.
  10. An Oasis of Healing. Curcumin. Published Sep 03, 2019. https://www.anoasisofhealing.com/curcumin/, accessed April 11, 2022.
  11. An Oasis of Healing. Health Articles. Curcumin for Cancer. Published Jun 07, 2021. https://www.anoasisofhealing.com/curcumin-for-cancer/, accessed April 8, 2022.
  12. An Oasis of Healing. Health Articles. The Power of Curcumin to Fight Cancer. Published Jun 21, 2021. https://www.anoasisofhealing.com/the-power-of-curcumin-to-fight-cancer/, accessed April 8, 2022.
  13. Shoba G, Joy D, Joseph T. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta med 1998; 64: 353-56.
  14. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006–. Turmeric. 2022 Mar 21. PMID: 30000906.