Zinc bound in yeast promotes superior bioavailability, claims study

One of the studies demonstrated that zinc-enriched yeast was 3.7 times more bioavailable - absorbed and found in greater concentration in the liver - than the zinc gluconate, report the scientists.

Zinc, one of the most plentiful trace elements in the body, second only to iron, mediates many physiological functions.

It is believed to be essential for maintaining a healthy immune system; recent science suggests the mineral could also influence memory, muscle strength and endurance in adults.

Zinc nutrition in very young children has been related to motor, cognitive and psychosocial function.

"Little was known about the relative bioavailability of the different sources of zinc, and how this may impact the clinical outcome," said Dr Thomas Tompkins, Microbiology and Biochemistry director for Institut Rosell/Lallemand, and co-investigator in both studies.

"[Our] comparative study has demonstrated the clinical relevance of the form of zinc supplement in the relative bioavailability of the mineral," he added.

Today's mineral supplement market offers a swathe of different forms, among these mineral-enriched gluconates and yeast are considered two of the more biologically available supplements.

For the first study, results for which were published last year, the objective was to demonstrate whether zinc was absorbed better by healthy male volunteers when given supplements where the mineral is found organically bound in yeast (using Lallemand's zinc yeast product Lalmin Zn) or as a salt gluconate form.

The trial used a randomised, two-way crossover design.

Urine, blood, and faecal samples were collected and analyzed over a 48 hour period after a single dose of supplement.

The net zinc balance and the relative bioavailability were calculated.

While no differences were observed in urine excretion of the two supplements, zinc gluconate gave higher zinc concentrations in the blood in the first six hours but also showed greater losses in the faeces.

" Zinc yeast also increased in blood with time but showed significantly less loss in the faeces ," the scientists report.

Thus, the net zinc balance after 48 hours for zinc yeast was 9.46, and for the gluconate it was -2.00, indicating that Zn gluconate supplementation contributed to a net loss of zinc, they added.

The purpose of the second study - that also used Lallemand's Lalmin Zn product - was to use zinc or copper deficient rats to determine whether the organically bound mineral in yeast or the salt gluconate form was more bioavailable.

The scientists write that "it was demonstrated that zinc-enriched yeast was 3.7 times more bioavailable than the zinc gluconate and that copper-enriched yeast was 1.4 times more bioavailable than the Cu gluconate."

While the zinc yeast product from Lallemand Health Ingredients (LHI) has been on the European market for several years, the Copenhagen-based firm is, like its competitors, awaiting approval for the positive list from Europe's risk assessor, the European Food Safety Authority.

For the industry, the lack of an EFSA decision is still a clear barrier to trade.

"This is a problem for us and our competitors.

No customer is going to go ahead with formulation until approval is met," Julie Rosenborg, area sales manager at LHI tells NutraIngredients.com.

Indeed a sentiment shared across the industry.

The recent Vitafoods trade show highlighted a drop in ingredient innovation, suggesting that the waiting game on approval may be stifling innovation across the board.

LHI is expecting approval from EFSA for the mineral enriched yeast supplement within the year, with ongoing research and development into a brand that "has a key selling point, the superior bioavailability of our yeast," added Rosenborg. Source: Biological Trace Element Research (Humana Press) Published online 17 July 2007, doi:Volume 120, Numbers 1-3 / December, 2007

"Clinical Evaluation of the Bioavailability of Zinc-enriched Yeast and Zinc Gluconate in Healthy Volunteers" Authors: Thomas A. Tompkins, Nadine E. Renard and Akira Kiuchi Source: Biological Trace Element Research (Humana Press) Published online 11 May 2007, doi:Volume 118, Number 2 / September, 2007 "Comparative Bioavailability of Mineral-enriched Gluconates and Yeast in Rat Liver After Depletion-Repletion Feeding" Authors: Joe A. Vinson, Thomas A. Tompkins and Gabriel A. Agbor