Novel food information: D-tagatose

On this page

• Background
  1. Introduction
  2. Manufacturing of the enzymatically synthesized D-tagatose
  3. Dietary exposure
  4. Nutrition
  5. Microbiology
  6. Chemistry
  7. Toxicology
  8. Allergenicity
• Conclusion

Background:

Health Canada has notified Bonumose LLC Company that it has no objection to the food use of D-tagatose as a food ingredient and sweetening ingredient in order to fully or partially replace existing added sugars. The Department conducted a comprehensive safety assessment of this D-tagatose according to its Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based upon internationally accepted principles for establishing the safety of foods with novel traits.

The following provides a summary of the notification from Bonumose LLC Company and the evaluation by Health Canada. This document contains no confidential business information.

1. Introduction

Bonumose LLC Company has enzymatically synthesised D-tagatose, which is a monosaccharide ketohexose and an epimer of D-fructose isomerized at C-4 that is naturally present in small quantities in dairy, whole wheat, white beans, and various fruits.

Bonumose's D-tagatose is manufactured from food-grade maltodextrin through a well-defined enzymatic cascade involving food-grade enzymes immobilized on a weak base anion exchange resin column, before being subjected to further downstream purification steps. The final crystalline D-tagatose product exhibits a purity of ≥ 99 % as demonstrated in three non-consecutive batches.

D-tagatose production involves six non-commercially^{Footnote 1} available enzyme preparations that are derived from genetically modified strains of Escherichia coli. A commercially available pullulanase enzyme preparation is also used in D-tagatose production. Those seven enzymes are considered reactants by Health Canada and are not considered to be food additives. Therefore, they are not subjected to premarket review under the Food and Drug Regulations. However, the petitioner is responsible for ensuring that the use of any substances in the manufacture of D-tagatose does not result in a violation of section 4 of the Food and Drugs Act.

The safety assessment performed by the Food Directorate evaluators was conducted according to Health Canada's Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based on harmonization efforts with other regulatory authorities and reflect international guidance documents in this area (e.g., Codex Alimentarius). The assessment considered: how D-tagatose was developed, its manufacturing process and specifications, and whether D-tagatose poses a nutritional safety issue as well as the potential for this substance to be toxic or cause allergic reactions. Bonumose LLC Company has provided data to support that D-tagatose is safe for use as food ingredient and sweetening ingredient in Canada.

The Food Directorate has a legislated responsibility for the pre-market assessment of novel foods and novel food ingredients, as detailed in Division 28 of Part B of the Food and Drug Regulations (Novel Foods). D-tagatose is considered to be a novel food under the following part of the definition of novel foods: "(a) a substance, including a microorganism, that does not have a history of safe use as a food".

2. Manufacturing of the enzymatically synthesized D-tagatose

All six food-grade non-commercially available enzyme preparations are derived from six production organisms, which were developed from the competent E. coli BL21(DE3) recipient strain. The enzyme-encoding genes of the six non-commercially available enzyme preparations were cloned in a manner that only those genetic elements were taken from the donor organisms.

The pullulanase enzyme preparation is commercially available in the U.S.A. under a self-determined GRAS.

The pullulanase source organismand E. coli strain BL21(DE3) are known to be non-pathogenic and non-toxigenic, are not listed in Schedule 2 to 5 of the Human Pathogens and Toxins Act, and are Risk Group 1 microorganisms according to the PHAC ePATHogen.

The manufacturing processes of the non-commercially available enzyme preparations involved flocculation and centrifugation of the biomass followed by several purification steps. The purity of the enzyme preparations were demonstrated by SDS-PAGE analysis where a predominant band exhibiting the expected molecular weight was observed for each non-commercially available enzyme preparation.

Enzyme immobilization was accomplished using positively charged resin that interacts with negatively charged enzymes. Following enzyme immobilization to the resin, the column was washed several times with physiological buffers to rinse off any unbound molecules, which resulted in a column containing only the immobilized enzymes prior to adding maltodextrin substrate.

Following enzyme immobilization, an aqueous food-grade maltodextrin solution was circulated into the column resulting in the synthesis of D-tagatose molecules. Several manufacturing steps were performed subsequently in order to reach a high purity D-tagatose in a crystalline form. This was achieved through a series of filtration / diafiltration, chromatography, evaporation, crystallization, and filter dryer steps. These steps also serve as barriers to microbial growth and result in the removal of most enzyme production process remnants that may have been present in the column.

3. Dietary exposure

Bonumose LLC Company estimated average intake by age group assuming that D-tagatose would replace 30% of all added sugars. Added sugar content was determined based on third-party analyses of food consumption data from the Canadian Community Health Survey - Nutrition (Cycle 2.2)^{Footnote 2} . The maximum mean intake was estimated to be 24 grams per day. Given the lack of upper-bound intake estimates from the CCHS data, these intakes were estimated using the 80th to 100th percentile intakes of added sugar based on data from the National Health and Nutrition Examination Survey (2011-2012) conducted in the United States (and assuming that D-tagatose would replace 30% of all added sugars). The maximum upper-bound intake was estimated to be 53 grams per day, and this level is expected to be representative of an upper-bound exposure for the general Canadian population.

4. Nutrition

D-tagatose is partially absorbed from the small intestine and unabsorbed amounts can be fermented to short-chain fatty acids by colonic microflora. However, the magnitude of both these actions remains uncertain.

Interpretation of the Food and Drug Regulations indicates that D-tagatose should be declared as carbohydrate and sugars for labelling purposes.

The energy conversion factor of D-tagatose for labelling purposes is uncertain. As it reflects the most recent and comprehensive assessment, the energy conversion factor (12.5 kJ/g or 3 kcal/g) estimated by the European Food Safety Authority's Panel on Dietetic Products, Nutrition and Allergies is considered to best reflect the current state of the scientific evidence until such time that additional data is available to calculate a more accurate value.

Gastrointestinal symptoms such as bloating, belching, flatulence, and laxation may be experienced by excessive consumption of products containing D-tagatose, e.g., 30 grams per serving. These symptoms are consistent with the effects of other incompletely absorbed carbohydrates including several sugar substitutes. While the likelihood of occurrence increases with the amount consumed, sensitivity variation between individuals, as well as the possibility of tolerance development with frequent consumption have also been reported. The petitioner indicated that, in foods containing large amounts of sucrose (e.g., soft drink), D-tagatose is typically used only as a partial replacement or with other sucrose alternatives such as a high intensity sweetener. As such, these symptoms are expected to occur when products containing D-tagatose are consumed in an excessive amount.

Overall, gastrointestinal symptoms due to excessive consumption of D-tagatose are well documented internationally, are characterized as mild, transient, and not experienced by all consumers. Therefore, they are not considered to pose a significant health or safety concern.

Health Canada did not identify further nutritional food safety concerns with the proposed use of D-tagatose in foods.

5. Microbiology

The notified product exhibits a high sugar concentration and is to be sold as a crystalline powder. Based on these properties, the potential for microbial growth is expected to be low, hence expecting microbial contamination to be low.

The microbiological specifications and validated testing methods were provided for the final D-tagatose. Certificates of analysis were provided for the final D-tagatose product for three non-consecutive batches. The specifications, methods and test results were all deemed to be acceptable. The petitioner also successfully demonstrated the absence of the production organisms in the final product.

The company confirmed the absence of enzyme preparation and production organism-derived proteins in their product through means of chromatography and Bradford protein quantification analysis assay performed during the pilot-scale production and the final D-tagatose product, respectively.

As part of the fermentation process to manufacture all six non-commercially available enzyme preparations, the petitioner added kanamycin and IPTG in the industrial culture media to maintain a stable growth of production organisms and induce enzyme expression, respectively. The company demonstrated the absence of kanamycin activity and the kanamycin resistance encoding gene (i.e., nptII gene) in the final product using Kirby-Bauer disk diffusion susceptibility test and qualitative PCR assay specific to the nptII gene, respectively. Also, the presence of IPTG in the final product is very unlikely since various manufacturing steps took place during the enzyme processing (continuous diafiltration and dilution) and D-tagatose manufacturing process (washing off the column prior to adding maltodextrin, ultrafiltration, ion exchange, and affinity chromatography), contributing to its removal.

Health Canada did not identify any microbial food safety concerns with the proposed use of D-tagatose in foods.

6. Chemistry

Specifications for D-tagatose (CAS # 87-81-0) are set out in the Food Chemical Codex (FCC) and the Combined Compendium of Food Additives Specifications prepared by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), including a limit on lead concentration of no more than 0.1 mg/kg. Health Canada considers the limit on lead in FCC and JECFA specifications to be suitably low.

Lead concentration from batch analyses results were provided by the petitioner, demonstrating that D-tagatose consistently meets the limit for lead set out in the FCC and JECFA specifications. The petitioner's specifications for arsenic, cadmium, and mercury are acceptable and can be consistently met based on the analytical results for D-tagatose provided by the petitioner. Overall, the potential exposure to arsenic, cadmium, lead and mercury from the proposed use of D-tagatose is not expected to be of concern for human health.

A list of substances used in the D-tagatose manufacturing process was included in the submission. No food safety concerns were identified with the use of these substances.

Health Canada did not identify any chemical food safety concerns with the proposed use of D-tagatose in foods.

7. Toxicology

The publicly available toxicological data for D-tagatose, including assessments from other organizations namely the JECFA, Food Standard Australia/New Zealand (FSANZ), and the US FDA, were reviewed. The animal data included short-term studies, genotoxicity studies, a developmental study, and a modified carcinogenicity study (with special focus on the liver). Human data were also available, including for sensitive subpopulations such as diabetic and hyperuricemic individuals.

The toxicological database demonstrated a lack of systemic toxicity and genotoxicity in the animal studies. An increase in liver weight and hypertrophy, accompanied by glycogen accumulation, were observed in the short-term studies after consumption of large amounts of D-tagatose. However, there was a lack of corresponding histopathological effects in a well-conducted 90-day study in rats, and in a 2-year rat carcinogenicity study designed specifically to analyze for effects in the liver. The effects observed in the animal short-term studies were therefore not toxicologically relevant. A conservative NOEL of 5% in the diet (corresponding to 2.3 g/kg bw/day) was established based on the results of the 90-day oral toxicity study.

Studies conducted in both healthy and diabetic individuals suggest that single doses of D-tagatose ranging from 5 to 75 g can have a minor blunting effect on serum glucose levels when administered with a meal or glucose load. However, when a large single dose (75 g) of D-tagatose was administered without any accompanying source of glucose in both healthy and diabetic individuals, no changes to serum glucose or insulin levels were observed. Because diabetics closely monitor their blood sugar (both generally, as well as prior to administering insulin), any minor impact of D-tagatose on serum glucose levels, and resultant insulin administration, would not be considered to pose a safety concern.

Based on what is known about the metabolism of D-tagatose, there is potential for an increase of uric acid levels in the blood. This effect is similar to what is observed for the metabolic process of D-fructose, although the potential for accumulation is considered greater for D-tagatose. However, several studies demonstrated that consumption of D-tagatose up to 30 g as a single dose, and up to 75 g per day in divided doses, did not result in clinically significant differences in serum uric acid levels; any increase was temporary, and generally did not exceed "normal" values as reported in the literature.

One study conducted in hyperuricemic individuals that administered D-tagatose as a single dose of 15 g also did not result in any clinically significant increases in serum levels of uric acid. The lack of clinical significance, combined with the transient nature of the effect even at higher doses, means that even a slight increase in serum uric acid levels would not pose a safety concern in the general population or in these sensitive individuals.

An estimated daily intake (EDI) was calculated, resulting in a maximum mean intake of 24 g per day (0.34 g/kg bw/day in a 70 kg individual), and 53 g per day (80-100th percentile; 0.76 g/kg bw/day in a 70 kg individual). These intakes were below the NOEL of 2.3 g/kg bw/day from the well-conducted rat study.

Given that the NOEL is highly conservative, the lack of adverse toxicological findings in traditional toxicological studies, the lack of significant health effects in human studies, and the fact that it has been permitted for use for 20 years in other countries, indicates that there is no concern for safety. This conclusion is dependent on the ingredient meeting FCC specifications for purity (i.e., > 98%), which the petitioner has reported to be the case.

As noted by JECFA and FSANZ, due to similarities in metabolic pathways between D-tagatose and fructose, D-tagatose may be unsuitable for individuals with Hereditary Fructose Intolerance (HFI) for whom consumption of fructose leads to a variety of adverse effects. HFI is a rare metabolic disorder usually detected in early childhood. Diagnosed individuals typically receive counselling to assist them to correctly identify and avoid "problem foods". D-tagatose will be declared in the list of ingredients on product labels, which would be sufficient to allow consumers to avoid D-tagatose in foods based on dietary counselling.

Health Canada did not identify further toxicological food safety concerns with the proposed use of D-tagatose in foods.

8. Allergenicity

The petitioner indicated that D-tagatose is not expected to pose an allergenic risk because it is not a proteinaceous substance. Analysis of several samples indicate no presence of the enzymes used to produce this substance. The petitioner is not aware of any documented allergic reactions despite numerous studies conducted in humans, as well as the fact that it has been permitted for use for 20 years in other countries.

Health Canada did not identify any allergenicity food safety concerns with the proposed use of D-tagatose, provided purity remains aligned with FCC standards.

Conclusion:

Health Canada's review of the information presented in support of the use of D-tagatose does not raise concerns related to food safety that would prevent this substance from entering the canadian food supply.

The assessment revealed that gastrointestinal symptoms such as bloating, belching, flatulence, and laxation may be experienced by excessive consumption of products containing D-tagatose. These symptoms are consistent with the effects of other incompletely absorbed carbohydrates, including several sugar substitutes, are well documented internationally, are characterized as mild, transient, and not experienced by all consumers. Therefore, they are not considered to pose a significant health or safety concern.

The assessment also revealed that D-tagatose may be unsuitable for individuals with Hereditary Fructose Intolerance for whom consumption of fructose leads to a variety of adverse effects due to similarities in metabolic pathways between D-tagatose and fructose.

Health Canada's opinion refers only to the food use D-tagatose as food ingredient and sweetening ingredient.

This Novel Food Information document has been prepared to summarize the opinion regarding the subject product provided by the Food Directorate, Health Products and Food Branch, Health Canada. This opinion is based upon the comprehensive review of information submitted by the petitioner according to the Guidelines for the Safety Assessment of Novel Foods.

(Également disponible en français)

For further information, please contact:

Novel Foods Section
Food Directorate
Health Products and Food Branch
Health Canada, PL2204A1
251 Frederick Banting Driveway
Ottawa, Ontario K1A 0K9
bmh-bdm@hc-sc.gc.ca