Warning letter cites NDI status of magnesium ingredient but doesn't raise safety concern

The Food and Drug Administration has issued another warning letter taking a company to task for marketing a product with an ingredient that lacks a New Dietary Ingredient filing. But one observer wonders why more such letters haven’t come from the agency.

Missing backlog

“When Dan Fabricant was at the agency all they would talk about is how many products had ingredients with NDIs filed for them and how many more should have,” said Justin Prochnow, a principal in the law firm Greenberg Traurig.

“The idea was that there were thousands and thousands of products like that out there. It’s somewhat amazing to me that for all of that, how many warning letters mentioning NDIs have we seen?  Five?” Prochnow told NutraIngredients-USA.

This most recent warning letter was issued to Nutri Spec, Inc., a Mifflintown, PA-based dietary supplement manufacturer. The letter took the company to task on a variety of GMP-related violations at both of its facilities, one in Pennsylvania and the other in Indiana.  Nutri Spec manufactures a variety of dietary supplements aimed at practitioners that purport to provide patient specific nutrition via vitamins and minerals. 

NDI status mentioned at end of letter

The warning letter cites a number of violations that focus on lack of process controls, including inadequate batch production records, missing master manufacturing records, lack of written procedures for labeling and packaging and failure to hold reserve samples of each batch.

Balancing the body’s mineral needs appears to be a key part of Nutri Spec’s formulation strategy and to that end the company includes a wide array of mineral formulations in its products. The company uses at least six different forms of magnesium, including magnesium glycinate, magnesium gluconate, magnesium aspartate, magnesium citrate and magnesium orotate.  But toward the end of the warning letter FDA singled out another, magnesium thiosulfate hexahyrate, for special attention.

“With regard to the magnesium thiosulfate hexahyrate that you use in some of your dietary supplement products, including Oxygenic A-Plus, please provide evidence that this ingredient has been used as a dietary ingredient in a dietary supplement before October 15, 1994. If an ingredient is not found to be used and marketed before this date, you are subject to the new dietary ingredient (NDI) requirements,” the agency wrote.

Is it a safety concern?

Prochnow said this particular mention was interesting because past warning letters mentioning an ingredient’s NDI status have hinged on the agency’s concern that the ingredient might pose a health risk and its safety had not been established, as was the case with DMAA. This mention doesn’t seem to fall in that category, he said. It begs the question whether the agency is moving into a new era when checking the NDI status of certain ingredients may become a matter of bureaucratic course rather than hinging on a pressing safety issue.

“It was almost an afterthought in this letter,” Prochnow said. “Most of the warning letters about NDIs come when they have a specific safety question for an ingredient. They usually mention that there is no safety evidence for the ingredient, and I didn’t see in this letter that FDA had any specific safety question on that ingredient.

“We are still waiting for the updated NDI draft guidance three and a half years later. Maybe they are going to start mentioning NDI status in warning letters more and maybe we will see a wave of them,” he said.