Turmeric: Metabolic Health Powerhouse?

Improved Fasting Blood Sugar and HbA1c Levels
Brazilian researchers led by Ingrid de Meloa at the Federal Institute of Alagoas (Alagoas, Brazil) recently conducted a meta-analysis and review of randomized controlled trials to assess the effect of curcuminoid-containing turmeric extracts on blood sugar regulation.² The researchers included studies that were conducted in adults aged 18 or older and had a placebo control where treatment lasted longer than four weeks. Overall, eleven trials were included in the analysis. The primary outcome was changes in fasting blood glucose levels, while secondary outcomes included changes in hemoglobin A1c (HbA1c) levels and measures of insulin resistance.

Results of the meta-analysis revealed a significant decrease in HbA1c levels and decreases in fasting blood glucose; however, no significant changes were found in HOMA-IR, a measure of insulin resistance. Interestingly, supplementation of isolated curcumin or combined curcuminoids was found to be most effective in those with some degree of blood sugar dysregulation, including in those with diabetes, but not in non-diabetic individuals, indicating their effectiveness in those with more advanced blood sugar issues. This research confirms that turmeric extracts can play an important role as a component of a therapeutic plan for supporting healthy blood sugar levels.

References:
2. Melo ISV, et al., “Curcumin or combined curcuminoids are effective in lowering the fasting blood glucose concentrations of individuals with dysglycemia: Systematic review and meta-analysis of randomized controlled trials,” Pharmacological Research. Published online September 18, 2017.

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Enhanced Fatty Acid Metabolism
A team of researchers from Harbin Medical University (Harbin, China) aimed to find one of the potential mechanisms whereby curcuminoids exert their glucose-lowering effects.3 In previous animal research the same investigators found that curcuminoids led to significant decreases in blood sugar levels and improved insulin resistance by reducing serum levels of free fatty acids and by enhancing fat oxidation in muscle tissue. The current human study was designed to determine whether these effects held true in diabetic patients. Overweight diabetic individuals were assigned to supplement with 300 mg/day curcuminoids or a placebo for three months. A total of 100 participants completed the trial.

Supplementation with the curcuminoids led to significant decreases in fasting blood glucose and insulin resistance, while at the same time significantly lowering serum total free fatty acids and triglycerides. There was also an accompanying increase in the activity of the enzyme, lipoprotein lipase, which breaks down triglycerides into free fatty acids. Thus, an important mechanism of curcuminoids in humans may be their ability to reduce fasting blood sugar levels by promoting fatty acid oxidation and utilization.

References:
3. Na LX, et al., “Curcuminoids exert glucose-lowering effect in type 2 diabetes by decreasing serum free fatty acids: a double-blind, placebo-controlled trial,” Molecular Nutrition and Food Research, vol. 57, no. 9 (September 2013):1569-1577

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Improved Adiponectin:Leptin Ratios
Previous research has found that curcumin offers benefits to those experiencing insulin resistance. Yunes Panahi and colleagues from Baqiyatallah University of Medical Sciences (Tehran, Iran) investigated in a 2016 study whether this beneficial effect occurred through curcumin’s interactions with the adipokines adiponectin and leptin.⁴ Adiponectin is known to mediate an insulin-sensitizing effect while leptin is a hormone that is known to be increased in obesity, but whose ultimate net effect is to inhibit appetite, stimulate thermogenesis, enhance fatty acid oxidation, decrease glucose, and reduce body fat in the obese state.⁵ Improving the ratio of adiponectin to leptin is thought to support healthy insulin function.

In the randomized, placebo-controlled trial, individuals with metabolic syndrome were asked to supplement with curcumin (1,000 mg/ day) or a placebo for eight weeks. Serum levels of adiponectin and leptin were measured before and after the intervention.  Curcumin treatment was associated with a significant increase in serum adiponectin and a reduction of serum leptin levels, a potential mechanism for curcumin’s ability to support healthy insulin sensitivity.

This study was conducted with Sabinsa's (East Windsor, NJ) proprietary Curcumin C3 Complex ingredient.

References:
4. Panahi Y, et al., “Effects of supplementation with curcumin on serum adipokine concentrations: A randomized controlled trial,” Nutrition, vol. 32, no. 10 (October 2016):1116-1122

5. Yadav A, et al., “Role of leptin and adiponectin in insulin resistance.” Clinica Chimica Acta, vol. 417 (February 18 2013): 80-84

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Antioxidant and Anti-inflammatory Effects
Curcumin is well-known for its antioxidant and anti-inflammatory benefits and these mechanisms likely contribute to its usefulness in managing several aspects of metabolic syndrome. Egyptian researchers recently sought to determine the role antioxidant and anti-inflammatory functions of curcumin play in metabolic syndrome by studying its effects in male albino rats.⁶

Researchers induced metabolic syndrome in rats by feeding them a high-fat diet. The rats were administered curcumin (200 mg/kg body weight orally once per day) or were assigned to the untreated group for eight weeks. Body weight, blood pressure, insulin resistance, and levels of serum glucose, insulin, leptin, blood lipids, malondialdehyde (a lipid peroxidation product), serum catalase (an antioxidant), and inflammatory markers (including NF-KB and TNF-α) were evaluated during the study period. While the control diet produced several significant negative changes in these metabolic parameters, animals co-treated with curcumin experienced significant improvements in all glucose and fat metabolism markers, as well as in markers for oxidative stress and inflammation. The results indicated curcumin’s ability to significantly influence the body’s endogenous inflammatory and oxidative state, yielding substantial metabolic protection. This broad range of action makes curcumin a useful compound for ensuring healthy metabolic function and healthy blood sugar metabolism.

References:
6. Kelany ME, et al., “Curcumin improves the metabolic syndrome in high-fructose-diet-fed rats: role of TNF-α, NF-κB, and oxidative stress,” Canadian Journal of Physiology and  Pharmacology, vol. 95, no. 2 (February 2017): 140-150

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