Disagreement about carotenoid research raises again the question of what ‘natural’ means

By Hank Schultz

- Last updated on GMT

Disagreement about carotenoid research raises again the question of what ‘natural’ means

Related tags Carotenoids Lutein Zeaxanthin Eye health

A disagreement between researchers and an ingredient supplier about the import of recent carotenoid research raised again the sticky question of when processing steps might convert a natural ingredient into an artificial one.

A war of words erupted between researchers John Nolan PhD and Stephen Beatty, PhD and Kemin Industries​, supplier of a line of ingredients that contain lutein and zeaxanthin.  These carotenoids are important in eye health and are concentrated preferentially by the body in the retina.  Another carotenoid is found there, too:  meso-zeaxanthin, a sterioisomer of zeaxanthin.  Nolan’s research has featured an ingredient that contains all three carotenoids.

At a meeting earlier this summer of the International Carotenoid Society that took place in Lucerne, Switzerland, Nolan and Stephan Beatty PhD presented the results of some research that is still under peer review. Kemin, based in Des Moines, IA,  made a statement about what it believes are the main takeaways from this research. Nolan disagreed with the conclusions that Kemin drew from his presentation (and from the preliminary abstract that appeared as part of the show program). A version of that statement can be found on the Kemin website​.

Question raised about provenance of ingredient

Leaving aside the questions about the proper conclusions to be drawn from the research, the statement has this to say about the nature of meso-zeaxanthin:The (RS) meso-zeaxanthin contained in dietary supplements is synthetically made from lutein using high heat and a strong alkaline environment.

 As a reference for that assertion, Kemin cited a 1993 paper​ by Bone RA et al. The conclusion of that paper said that: The results strongly suggest that meso-zeaxanthin results from chemical processes within the retina. Noting that lutein exceeds zeaxanthin in plasma but that the combined zeaxanthin stereoisomers exceed lutein in the retina, the possibility was considered that meso-zeaxanthin is a conversion product derived from retinal lutein. Under non-physiologic conditions, the authors demonstrate that a base-catalyzed conversion of lutein to zeaxanthin yields only the meso-(3R,3'S) stereoisomer.

Food grade solvents

Nolan said the issue has come up before, and he has prepared a statement, or white paper of sorts, that addresses the question. The processing steps  are covered by a US patent held by Monterrey, Mexico-based Industrial Organica. Nolan said the ingredient is made from pelletized marigold flower petals that are extracted using hexane (mixed with acetone and methanol at a later step). The process involves treatment with an alkali solution and involves the use ofcontrolled temperature.

While the use of solvents like hexane and acetone is never something that ingredient developers are wont to trumpet from the mountain tops, these are commonly used processing aids in the industry. Nolan said in the production of the meso-zeaxanthin-containing extract, in common with standard industry practice, the volatile solvents are removed via evaporation.

All the processing aids used, such as potassium hydroxide and the solvents (hexane, acetone, methanol) used during the manufacturing process are food grade quality and comply with the applicable food law,​ Nolan said. Nolan took pains to point out that meso-zeaxanthin has met a number of stringent safety tests and the ingredient does have GRAS status (nor, for its part, has Kemin raised any safety concerns as such about this carotenoid).

Open question on what ‘natural’ means

So, how much processing equates to too much? How much heat is too much?  What is an acceptable pH range for ‘natural?’ These are questions that have hovered over the industry for decades, and they get thornier by the year as new processing technologies arise.

 Stefan Gafner PhD, chief science officer of the American Botanical Council​, said there’s no bright line in the sand to point to answer these questions.  Many ingredients that come from botanical feed stocks might include processing steps that could be seized upon to make the product look undesirable, much in the way that intermediate, procedural votes on legislation could be publicized to the embarrassment of a lawmaker.

Its a tricky question,​ Gafner told NutraIngredients-USA. It’s one that he had to wrestle with frequently in his earlier career with personal care products manufacturer Toms of Maine.  The company had a mission to source only ‘natural’ ingredients, but what would that mean?

At Toms of Maine we had six scientists in a group and we would go through every ingredient and all its processing steps. In the end there was always some parameter that we hadnt planned for where we had to make a decision as a group. Its not as black and white as people would like to make it out to be,​ he said.

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Natural - As a starting or finishing point.

Posted by Dr. Mark JS Miller,

The challenge here is "has the original natural form been altered by the processes to remove it and concentrate it?" And that is not clear, and so the exchange is blurry.
But there is a less blurry controversy involving carotenoids & it too involves where the starting end point is clearly different. That is astaxanthin.
Natural astaxanthin in our food is derived from algae (or food that consumers the algae). The 3d structure is an all trans bonds 3S, 3'S whereas synthetic astaxanthin has mixed isomers but dominantly 3R, 3'S and Cis bonds.
This "heavy" chemistry may seem unimportant but it is. Because of these differences, synthetic astaxanthin cannot form a trans-membrane bridge to protect it from lipid peroxidation. Twisting the molecule dramatically compromises its functionality. The final detail is that synthetic versions of astaxanthin are made from petrochemicals not a plant (algae).
Certainly not in keeping with natural health, and while synthetic is not approved for human consumptions it is entering the food chain via adulterated supplements and via farmed salmon where it is used a dye.
So while the lutein story may be full of rhetoric it is far more complicated than the clear issues with astaxanthin.

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Posted by Ari Maayan,

What a nice fairytale. Makes me all warm and fuzzy inside. That these toxic, carcinogenic volatile solvents can be totally removed via evaporation. If you believe that I have a bridge I want to sell you.

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