The curcumin (Curcuma longa) supplement market has been awash in buzz on its potential in a range of health and performance situations, but the heightened absorption and bioavailability challenges have created a market full of different types of curcumin ingredients. Its not as though responsible companies are not investing in research and development (R&D) to improve these offerings, but for each published study seeming to provide an answer to which ingredient type best overcomes these challenges, another study keeps the question open, unanswered fully.

2021 was no different. Published studies added to the knowledge base and moved the market generally forward, but the competition and debate continued. If not for adulteration and the attention spans of modern consumers, this would be an entirely healthy situation wher each tidbit of evidence and discovery, each one-upping in innovation of extraction and delivery technology, would boost the overall market.

One of the caveats of this "arms race," as Global Curcumin Association Executive Director Len Monheit calls it, is that the latest evidence tends to be funded or directly studied by one of the competitors. While this demonstrates companies are putting money into research, it also can introduce the air of bias, or at least potential conflicts of interest.

In April 2021, an online article ahead of print publication in the Journal of Nutrition looked at the pharmacokinetics of various forms of turmeric at the doses: standard turmeric extract (STE) with 95% curcuminoids (from Naturex, at 1,500 mg); liquid micellar curcumin containing 6% curcuminoids (NovaSOL from Aquanova AG, at 1,000 mg), a combo of piperine and 95% curcuminoid extract (Curcumin C3 Complex from Sabinsa, at 1,515 mg); a phytosome formulation of turmeric extract (18% to 22% curcuminoids), phosphatidylcholine (PC), and microcrystalline cellulose (Meriva from Indena, at 1,000 mg); and dried colloidal suspension of STE (30% curcuminoids), Quillaja saponaria (soapbark) extract, sunflower oil and acacia gum (Turnmipure GOLD from Naturex, at 300 mg).

The dosages used reflected the recommended dose and ingredients were researched for increased bioavailability. The researchers explained, "Consumers will be able to make informed decisions regarding which turmeric formulation to choose based on their real curcuminoid absorption capacity." The curcuminoid content of each was verified using ultra-high-pressure liquid chromatography (UHPLC)/tandem mass spectrometry (MS/MS).

In the randomized, open-labeled, crossover design, 30 healthy men and women sequentially consumed single doses of these and had 11 blood samples each drawn over a 24-hour period, and researchers assessed the dose-normalized AUC of total plasma curcuminoids. They found Turmipure GOLD was the most bioavailable low-dose extract of the bunch, providing "high unconjugated and conjugated curcuminoid absorption, with significant beneficial differences when compared with the high dose of standard extract."

It is important to note that the researchers were from Naturex, and the focus of the study was to compare Turmipure to market competitors. This isnt to suggest inaccurate results, only to highlight a potential conflict of interest. The study made it to print in July 2021 (J Nutr. 151[7]:1802-1816).

Another comparison surfaced in 2021, this time an analysis of retail-purchased curcumin finished products. In this case, NOW Foods purchased curcumin/turmeric products from Amazon in June 2021 and blind-tested for potency, heavy metals, labeling accuracy, and potential addition of synthetic curcumin. Of the 23 unknown brand products and two NOW products analyzed, only one clearly failed potency testing and four others tested very low, but without any specific label claim.

The labeling of products was an issue, with many saying "Turmeric Curcumin 1,650mg" on the front of the label, but listing breakdown amounts on the back or side from various sources such as turmeric root, turmeric extract and piperine. This effectively meant the 1,650 mg was not entirely curcumin as indicated on the front. "This can be perceived as deceptive since many customers do not know the difference between Turmeric, Turmeric Extract, Curcumin Extract, and Standardized 95% Extract," said Dan Richard, NOWs vice president of global sales and marketing.