Turmeric and Curcumin for MGUS: Promising Treatment or Hidden Risk? What Patients Need to Know

Table of Contents

• Key Points
• What Is MGUS and Why Is Turmeric Being Studied?
• A Patient's Story: When Turmeric Caused Breathing Problems
• How Curcumin Interacts with the Immune System
• Dendritic Cells: The Commanders of the Immune System
• The Role of Dendritic Cells in Common Variable Immunodeficiency (CVID)
• What Curcumin Does to Dendritic Cells
• Dendritic Cells in Patients with MGUS
• Curcumin, Turmeric and the General Public
• What This Means for Patients
• Study Limitations
• Recommendations for Patients
• Frequently Asked Questions
• Source Information

Key Points

• Curcumin may lower paraprotein in some MGUS patients, but it can also suppress immune function by inhibiting dendritic cell IL-12 production.
• A 57-year-old man with IgG1 deficiency developed bronchitis twice when taking turmeric at 1 g twice daily; symptoms cleared on stopping.
• Lower-dose turmeric (200 mg twice daily) relieved his intestinal symptoms without causing bronchitis for almost two years.
• Patients with MGUS, especially those with reduced normal immunoglobulins, should not take turmeric or curcumin without medical supervision.
• Natural products can cause toxicity at high doses or in susceptible individuals; watch for cough, wheezing, fever, or fatigue.

What Is MGUS and Why Is Turmeric Being Studied?

Curcumin, the major yellow pigment extracted from turmeric, has been rediscovered by modern science as a substance with great promise as a therapeutic agent. It is currently being tested in human clinical trials for a variety of serious conditions, including multiple myeloma, pancreatic cancer, myelodysplastic syndromes, colon cancer, psoriasis and Alzheimer's disease.

Recent pilot studies by Golombick and Diamond (2008) and Golombick et al (2009) reported that curcumin, in some patients with monoclonal gammopathy of undetermined significance (MGUS), decreases the paraprotein load (the abnormal antibody protein produced by plasma cells) and the urinary N-telopeptide of type 1 collagen bone turnover marker (a measure of bone breakdown). MGUS is a condition in which a monoclonal (M-) protein is present in the blood without evidence of multiple myeloma, Waldenström's macroglobulinemia, primary amyloidosis or related disorders.

The results are promising because an increasing paraprotein concentration is a known risk factor for malignant progression of these diseases. MGUS becomes more common with age. The prevalence gradually increases from 1.7% in individuals between 50 and 59 years to 6.6% in individuals above 80 years of age.

The average risk for malignant progression in an individual with MGUS is approximately 1.5% per year. MGUS is therefore a serious condition — it leads to an increased risk of mortality, not only due to malignant transformation, but also due to coexisting clinical conditions. However, many patients with MGUS never develop symptoms and eventually die of unrelated causes. As a consequence, the medical profession has been very cautious about treatment.

To date, only regular observation ("watchful waiting") with no treatment is recommended for these patients. This is based on the fear that treatment with, for example, alkylating agents may induce secondary leukemia. Curcumin is believed not to pose this risk.

Turmeric is widely consumed in Southeast Asia, and its use as a dietary spice and pigment is slowly growing worldwide. In India in particular, it has been used for centuries as a traditional medicinal product. Turmeric powder is easily available as a food component in Asia, the Americas and Europe. Since it has been consumed for such a long time, the product is considered safe. Average intake in the adult Indian population is estimated at 2 g/day (containing up to 200 mg curcumin). Phase I clinical trials indicate that even doses of up to 8 g/day of extracted curcumin (diferuloylmethane) provoke only minimal toxicity in healthy volunteers.

In a commentary on the Golombick et al study, Dr. S.V. Rajkumar of the Mayo Clinic emphasized the crucial importance of developing new methods to prevent the malignant progression of MGUS. The authors of this review agree that further trials with the aim of delaying progression in MGUS are warranted — but they express an important word of caution based on a case in which moderate doses of turmeric appeared to cause toxicity, possibly related to immunosuppression.

A Patient's Story: When Turmeric Caused Breathing Problems

This review article reports the case of a 57-year-old male patient with mild hypogammaglobulinemia (low levels of antibodies in the blood) and a subnormal level of IgG caused by an IgG1 subclass deficiency. His antibody levels are shown below:

The patient had suffered since early childhood with otitis media (middle ear infections), chronic rhinosinusitis and, rarely, bronchitis. The immune disorder was also present in other family members, sometimes combined with IgG3 deficiency. Throughout his life, the patient developed onychomycosis (fungal nail infections), plantar warts and flat warts that were rather resistant to treatment. Notably, on two occasions, long-standing plantar warts that had earlier resisted cryotherapy, X-ray irradiation, topical fluorouracil applications and injections with transfer factor spontaneously cleared after the patient took multivitamin tablets for several months at doses sometimes exceeding the recommended dietary allowance. The patient had no history of allergies.

Chronic constipation in early life was followed by post-infectious irritable bowel syndrome (IBS) from the age of 25. Prior treatment with salazopyrine had not improved the situation, and treatment with antibiotics had only a temporary effect.

An encouraging pilot study by Holt et al (2005) on the use of curcumin in inflammatory bowel disease led the patient to suggest using turmeric for his intestinal problems. His doctors proposed a dose of 1 g, two times per day, of the food component turmeric. (For comparison, Holt et al prescribed 1–1.5 g/day, but used 99.5% pure curcumin.) Within weeks, the patient's intestinal complaints became significantly milder, and he experienced a subjective improvement in quality of life. Positive results of curcumin for HIV-associated diarrhea had also been described, confirming the usefulness of curcumin for bowel problems even in severely immunocompromised patients.

However, within 6 weeks of starting turmeric, the patient developed mild bronchitis with chronic cough and wheezing. This was surprising, since traditional Indian medicine recommends turmeric for a number of health problems, including sinusitis.

Turmeric treatment was discontinued, and the bronchitis completely cleared. It was re-initiated several weeks later — and this time, the first signs of wheezing and bronchitis returned within 4 weeks. Turmeric was again discontinued for 3 weeks.

When re-started at a lower dose of 200 mg two times per day, no wheezing or bronchitis developed, and the dose was still sufficient to significantly improve the intestinal problems. The patient has continued this lower-dose treatment intermittently for almost 2 years with satisfaction and no toxicity.

The patient's IgG1 deficiency is relevant: one in two patients with IgG1 deficiency develops ear, nose, throat and bronchial problems, while one in five develops gastrointestinal problems. His condition is difficult to distinguish from a mild form of common variable immunodeficiency (CVID).

The development of bronchitis after turmeric or curcumin use has, to the best of the authors' knowledge, never been reported in the literature. It cannot be ruled out that this patient may have been more susceptible to turmeric toxicity than other patients because of his mildly compromised immune system and/or a related tendency to develop vitamin B6 deficiency — which is itself connected to immune function. Interestingly, a recent study in which CVID was defined by a reduction in serum IgG (<7 g/L), recurrent bacterial airway infections and a poor response to vaccinations, found a vitamin B6 deficiency in one out of three patients. Vitamin B6 supplementation resulted in a significant increase in CD4+ T cells (a key type of immune cell) in these patients, while the concentration of serum immunoglobulins remained unchanged.

How Curcumin Interacts with the Immune System

A recent study in Wistar rats demonstrated that prolonged intraperitoneal curcumin injections did not impair the cytotoxic function of natural killer (NK) cells, a type of white blood cell important for fighting tumors and viruses. Moreover, the generation of reactive oxygen species and nitric oxide from macrophages (cells that engulf and destroy pathogens) and levels of Th1 regulatory cytokines remained unaltered. On the basis of these results, that study concluded that curcumin is a safe pharmacological molecule for immune cells in the body.

However, the effect of curcumin on dendritic cells (DCs) was not investigated in that study. This is a significant gap, because dendritic cells are critical for generating an immune response. After DCs are activated, they mature and migrate to the lymphoid tissue, where they "present" antigens to T lymphocytes, stimulating a specific (adaptive) immune response. In other words, they act as the command centers that direct the rest of the immune system.

Dendritic Cells: The Commanders of the Immune System

Dendritic cells play a key role in mucosal viral infections. Infection with respiratory viruses mobilizes immune cells, including both myeloid (m) and plasmacytoid (p) dendritic cells, to the site of viral entry and promotes their replication in the respiratory tract. The increased number of pDCs in the nasal compartment significantly correlates with viral load and is associated with a decrease in the number of pDCs in the blood. High numbers of both DC subsets are found in respiratory secretions weeks after the acute symptoms of the viral infection have resolved.

The Role of Dendritic Cells in Common Variable Immunodeficiency (CVID)

In patients with common variable immunodeficiency (CVID) — a group of disorders characterized by low antibody levels and various T-cell defects — the differentiation, maturation and function of dendritic cells are severely perturbed. Specifically, DCs in CVID patients produce significantly lower amounts of interleukin-12 (IL-12), a signaling molecule essential for activating the Th1 immune response, after CD40 signaling, compared to healthy controls. The expression of maturation markers, including CD40 on the DCs themselves, was also significantly lower than in DCs from healthy donors.

Interestingly, experiments with neutralizing anti-IL-10 monoclonal antibodies indicate that IL-10 may not be the only factor responsible for this defective differentiation. Deficient IL-12 production by DCs is closely correlated with lymphocyte function in laboratory tests and with the absolute numbers of CD4 T cells in the blood. Although DCs in CVID patients look morphologically similar to DCs in normal subjects, their lack of IL-12 production and defective antigen presentation demonstrate significant functional defects.

On the other hand, CD40 ligand expression on stimulated T-helper lymphocytes in CVID patients appears similar to that in healthy controls. These findings — along with a more recent study showing selective deficits in blood dendritic cell subsets in CVID — point to an important role of defective differentiation and functioning of dendritic cells in the pathogenesis of immunodeficiency in CVID.

What Curcumin Does to Dendritic Cells

Almost 5 years before this review was published, researchers demonstrated that curcumin is a potent inhibitor of myeloid dendritic cell maturation in mice. In experiments conducted in living animals, curcumin-treated DCs migrated to the T-cell areas of secondary lymphoid tissue but failed to induce a normal cell-mediated contact hypersensitivity reaction (a type of allergic skin reaction). In particular, reduced IL-12 production observed after curcumin treatment indicated that curcumin induces an immature state in DCs.

Most of the effects of curcumin on the T-cell-differentiating properties of DCs were found to be a consequence of IL-12 inhibition. Curcumin-treated DCs failed to induce a normal cell-mediated immune response. On this basis, it was proposed that curcumin could be used to inhibit Th1 responses for therapeutic purposes — for example, to reduce inflammation in conditions such as arthritis.

But there is a critical downside: while Th1 activation plays a pivotal role in inflammation, Th1 cells are also protective against invading pathogens and tumors. In other words, the anti-inflammatory effect achieved by treating dendritic cells with curcumin comes with an immunosuppressive effect at the same time.

A recent study investigating the effects of curcumin on human dendritic cells found that curcumin prevented DCs from responding to immunostimulants. DC-induced CD4+ T-cell proliferation was prevented. Maturation markers were blocked, and the expression of cytokines and chemokines was inhibited. Migration was also reduced. The researchers concluded that curcumin dampens the Th1 response while promoting a Th2-permissive environment (a different immune pathway that is less effective against tumors and intracellular pathogens). They speculated that curcumin may disrupt the antigen-handling and antigen-presenting machinery of dendritic cells.

Since a Th1 pattern of cytokine secretion — in which DC-derived IL-12 plays an essential role — has been associated with protective antitumor responses, dampening the Th1 response with curcumin could be counterproductive in attempts to prevent malignant progression, at least in patients in whom dendritic cell maturation would already be compromised.

Dendritic Cells in Patients with MGUS

In patients with MGUS and multiple myeloma (MM) — which can result from malignant progression of MGUS — significant abnormalities exist in the distribution, phenotype and pattern of secretion of inflammatory cytokines by different subsets of dendritic cells from peripheral blood. Despite a reduced secretion of the inflammatory cytokines IL-1, IL-6, IL-8 and TNF (tumor necrosis factor) in both MGUS and MM, the production of IL-12 after short-term culture in the laboratory was similar in patients with MGUS and healthy controls.

Whether curcumin inhibits IL-12 production from dendritic cells in MGUS patients is a critical issue, given that immunosuppression is a known risk factor for the development and progression of MGUS. Studies of familial clusters of Waldenström's macroglobulinemia — another lymphoproliferative disease often preceded by MGUS — have found an increased frequency of IgM MGUS compared with the general population, and have provided data suggesting that the phenotypic spectrum may also include hypoglobulinemia (low antibody levels).

It is conceivable that immunosuppression by curcumin is only relevant in patients with MGUS who already have an impaired immune system and abnormally functioning dendritic cells — not in healthy controls. In this context, it is well known that in subgroups of MGUS patients, the non-affected immunoglobulins (the normal, healthy antibodies) are reduced. These patients show, on average, a higher risk for progression. Whether curcumin perturbs dendritic cell maturation and IL-12 production in these patients — and whether this leads to further immunosuppression and increased risk of MGUS progression — are issues that must be addressed in future clinical trials.

Curcumin, Turmeric and the General Public

In our developing "information society," findings reported in the scientific literature — or at least parts of them — are rapidly spread to the general public. Companies now include "natural substances" in their products for the health and cosmetic markets. For example, over the last few years, the benefits of polyphenols have been presented in advertising campaigns for health, diet and beauty products, and results of scientific studies have been used and quoted in this context.

This practice could be positive, were it not for the fact that increased public awareness about natural products has not countered the widespread misconception regarding their toxicity. "Natural" products are often assumed to pose little or no toxicity risk. In fact, natural products can — and do — induce significant toxicity when used by susceptible individuals, or when the dose is higher than what is normally consumed at dietary levels.

Because turmeric has been used for centuries, it is unlikely that problems will arise in healthy individuals when curcumin is ingested at or near the quantities normally found in the diet. However, at significantly higher doses, and/or in susceptible individuals, toxicity may occur. For example, the first case of complete atrioventricular block (a serious heart rhythm disturbance) associated with turmeric intake was described and published online in November 2009.

To date, scientific knowledge is insufficient for identifying all the risk factors or risk groups. The authors express their trust that this literature review and the illustrative case will alert the scientific community to the potential toxicity risk of curcumin in immunocompromised patients. They also hope that the general public will realize that, at doses higher than those found in a regular diet, short- or long-term harmful side effects may occur — and that healthcare professionals will inform patients about the existence of such risks.

What This Means for Patients

For patients with MGUS, this review carries an important dual message. On one hand, the pilot results with curcumin reported by Golombick et al are genuinely encouraging. Since an increasing paraprotein level is a known risk factor for malignant progression, a substance that can lower the paraprotein load and reduce bone turnover could potentially delay or prevent progression to multiple myeloma.

On the other hand, the case described here demonstrates that even a "natural" food component like turmeric can cause adverse effects in susceptible individuals — specifically, bronchitis that appeared twice when the patient took turmeric and resolved when he stopped. The immunological explanation is scientifically plausible: curcumin inhibits IL-12 production in dendritic cells, which dampens the Th1 response that protects against infections and tumors.

The concern is particularly relevant for MGUS patients because a substantial subgroup already has reduced levels of their normal (non-affected) immunoglobulins, and these patients have a higher risk of disease progression. In these patients, even mild additional immunosuppression from curcumin could theoretically tip the balance toward infection or malignant progression.

Study Limitations

It is important to recognize the limitations of this review. First, it describes a single case — one patient's experience does not constitute proof of turmeric toxicity. Second, much of the supporting evidence comes from laboratory studies (in vitro experiments) and animal studies, which may not directly translate to humans. Third, it is not known whether curcumin's effects on dendritic cells observed in mice and in laboratory cultures occur to the same degree in MGUS patients taking oral turmeric. Finally, the review raises important questions — whether curcumin inhibits IL-12 production from DCs in MGUS patients specifically, and whether this affects progression risk — but does not answer them; these questions require planned clinical trials.

Recommendations for Patients

Based on this review, patients should consider the following precautions:

1. Do not take turmeric or curcumin supplements without medical supervision if you have MGUS, particularly if you have a known immune deficiency or low immunoglobulin levels. The authors explicitly state that "a warning against the use of turmeric or curcumin without medical supervision in immunocompromised patients seems very opportune."
2. If your doctor recommends curcumin, start with the lowest effective dose. In this patient's case, 200 mg twice daily provided intestinal benefits without triggering bronchitis, while 1 g twice daily triggered symptoms on two separate occasions.
3. Watch for warning signs of infection or immune suppression, including persistent cough, wheezing, bronchitis, sinusitis, fever, or unusual fatigue. Report any of these symptoms to your healthcare provider promptly.
4. Remember that "natural" does not mean "risk-free." Turmeric has been used safely in food for centuries, but medicinal doses are significantly higher than dietary amounts, and effects can differ in people with compromised immune systems.
5. Do not self-treat MGUS. Current medical guidance for MGUS is "watchful waiting" with regular monitoring. Any use of supplements such as curcumin should be discussed with and monitored by a hematologist or other qualified healthcare professional.
6. Be aware that high-dose turmeric has been linked to serious side effects, including a reported case of complete heart block (atrioventricular block). Even if you are healthy, very high doses may not be safe.

The authors conclude: "Patients with MGUS, in whom the levels of non-affected immunoglobulins are reduced, should be carefully monitored for toxicity when curcumin is administered." This review serves as a reminder that even promising natural therapies require the same careful consideration of risks and benefits as any medical treatment.

Frequently Asked Questions

What is MGUS?

MGUS stands for monoclonal gammopathy of undetermined significance. It is a condition where a monoclonal protein is present in the blood without evidence of multiple myeloma, Waldenström's macroglobulinemia, or related disorders. It becomes more common with age and carries an average risk of malignant progression of about 1.5% per year.

Why is turmeric or curcumin being studied for MGUS?

Curcumin, the active ingredient in turmeric, is being tested because pilot studies reported that it decreased paraprotein load and bone turnover markers in some MGUS patients. Since rising paraprotein levels are a risk factor for malignant progression, researchers hope curcumin might help delay or prevent progression, though more trials are needed.

Can turmeric cause breathing problems?

Yes, in a reported case, a 57-year-old man with mild immune deficiency developed bronchitis and wheezing within weeks of taking turmeric. His symptoms cleared when he stopped, and returned when he tried it again at a higher dose. A lower dose did not trigger breathing problems.

How does curcumin affect the immune system?

Curcumin can inhibit the maturation of dendritic cells, which are key immune commanders. This reduces IL-12 production and dampens the Th1 immune response that defends against infections and tumors. While this can reduce inflammation, it may also cause immunosuppression, especially in people with already weakened immune systems.

Should I take turmeric or curcumin if I have MGUS?

The authors recommend that patients with MGUS should not take turmeric or curcumin without medical supervision, especially if they have low immunoglobulin levels or a known immune deficiency. Talk to your hematologist before using any supplement, as self-treatment is not advised, and current guidance for MGUS is watchful waiting.

What dose of turmeric was safe in the patient case?

In the case report, the patient developed bronchitis at 1 gram twice daily. When the dose was lowered to 200 mg twice daily, his intestinal symptoms improved without wheezing or bronchitis for almost two years. This suggests starting at the lowest effective dose may be safer, but medical supervision is essential.

What warning signs of immune suppression should I watch for?

Warning signs may include persistent cough, wheezing, bronchitis, sinusitis, fever, or unusual fatigue. If you are taking curcumin and develop any of these, report them promptly to your healthcare provider. Remember that 'natural' does not mean risk-free, especially at high doses or in people with compromised immunity.

Should I get a second opinion before trying turmeric or curcumin for my MGUS?

A patient with MGUS should seek a second opinion before starting turmeric or curcumin, particularly when immunoglobulin levels are low. The scientific evidence shows curcumin can inhibit dendritic cell maturation and IL-12 production, dampening the Th1 immune response that protects against infections and tumors. The case described shows bronchitis occurring twice at higher doses and resolving on discontinuation. Patients with reduced non-affected immunoglobulins have a higher progression risk, so any additional immunosuppression deserves careful review. A second opinion can clarify whether curcumin is advisable and what monitoring is needed. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

This patient-friendly article is based on the following peer-reviewed research publication:

• Original Title: "Curcumin for the prevention of progression in monoclonal gammopathy of undetermined significance: A word of caution (Review)"
• Authors: A.J.M. Vermorken, J. Zhu, W.J.M. Van de Ven, Y. Cui and J.P. Fryns
• Journal: Experimental and Therapeutic Medicine 1: 265–269, 2010
• DOI: 10.3892/etm.00000041
• Corresponding author: Dr. Fons Vermorken, Laboratory for Molecular Oncology, Department of Human Genetics, University of Leuven, Belgium

This patient-friendly article is based on peer-reviewed research. It is intended for educational purposes and should not replace professional medical advice. Always consult your healthcare provider before starting or stopping any supplement or medication.