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Fortification of sugar with vitamin A

Abstract
Introduction
Fortification procedure
Premix stability
Sugar fortification
Cost of fortification
Newer technologies for sugar fortification
Fortification of sugar with iron
Impact of vitamin A-fortified sugar on the population
References

Oscar Pineda

Oscar Pineda is affiliated with the Centro Latinoamericano de Nutrición y Estudios Metabólicos (CELANEM) in Guatemala City, Guatemala.

Mention of the names of firms and commercial products does not imply endorsement by the United Nations University.

Abstract

The technology for fortifying sugar with vitamin A was developed in Guatemala in the mid-1970s, and the Guatemalan government enacted legislation to make fortification mandatory in June 1974. This action was copied by other Central American governments. The fortification programme in Guatemala developed in two stages. In the first (1975-77), the fortification programme was evaluated four times at six-month intervals and was shown to be effective. The sugar industry was responsible for carrying out the programme, but the programme was suspended, mainly because of economic arguments. After 10 years of effort, the programme was restarted in 1989. At this time the programme was combined with an initial mass distribution of vitamin A capsules to pre-school children, which began the first successful social mobilization effort in the area. The programme was evaluated for six months and was shown to be effective in improving the vitamin A status of the Guatemalan population. This second stage has been active continuously since 1989. With improvements in the technology of fortification, new approaches have been tested, and now it is possible to obtain an excellent sugar doubly fortified with vitamin A and iron, using new iron products of high bioavailability that do not alter the organoleptic characteristics of the sugar and do not produce unwanted colour changes during processing. To avoid the rancidity of premixes, new processes of dry mixing have been developed in which no oil is used. This opens a real possibility for the fortification of sugar with other nutrients. Sugar fortified with vitamin A, iron, and zinc, either alone or in any combination, is commercially available in Brazil, where, under the guidance of the Latin American Centre of Nutrition and Metabolic Studies (CELANEM), the procedures have been developed using iron ammo acid chelated minerals.

Introduction

Vitamin A deficiency continues to be highly prevalent in developing countries. The World Health Organization (WHO) estimates that in at least 75 countries, the deficiency is a problem of public health importance [1]. Of the many approaches that have been taken thus far to control vitamin A deficiency, sugar fortification seems to be the most cost-effective method [2]. According to a UNICEF report on sugar fortification in Guatemala, the cost of fortification is about one-fifth of that of other interventions [3]. Because of the success of the sugar-fortification programme in Guatemala that was carried out for two years in the mid-1970s and initiated again and maintained since 1988, this approach has become the preferred intervention in those countries where it is feasible.

To bolster the potential of sugar-fortification interventions, UNICEF obtained a resolution from the Council of the International Sugar Organization during its meeting in Sao Paulo, Brazil, in May-June 1995. The resolution stated that the council agreed to facilitate fortification programmes in those countries where governments were considering such interventions.

In most countries, sugar fulfils the criteria listed by the Council of Food and Nutrition of the National Academy of Sciences of the United States as a good vehicle for fortification with specific nutrients [4,5]:

» The food used to supply the nutrient should be consumed in significant amounts by essentially all members of the targeted groups of the population;
» The addition of the nutrient will not cause any imbalance of essential nutrients;
» The nutrient is stable in the vehicle under normal conditions of storage and use;
» There is reasonable assurance that no excess intake will be induced.

» The food vehicle should be consumed by practically all the population;
» The daily intake of the carrier food should be essentially constant;
» Fortification should not alter the organoleptic characteristics of the vehicle;
» Production and processing of the food vehicle should be centralized;
» The cost of the fortification should be economical.

To initiate a programme of fortification of sugar with vitamin A, it is necessary to know with enough precision the levels of daily consumption of sugar by the population at large as well as by pre-school children. In Guatemala these values were 36 g/day for adults and 20 g/day for rural pre-school children.

Since there is no single level of fortification appropriate for every country, the rationales put forth in Guatemala as to the level of fortification to be used may aid other countries in which sugar fortification is been considered. These rationales were [6]:

» To add to the mean daily intake of sugar of the population the amount of vitamin A recommended by WHO for adult daily consumption. In principle, this level is considered high, since even the less privileged groups consume at least a fraction of their daily requirement for vitamin A;

» To add to the mean daily intake of sugar of the rural population a quantity of vitamin A that corrects the mean daily deficit in their dietary intake and raises it to the recommended amount;

» To add to the mean daily intake of sugar of rural pre-school-age children the mean safe level of intake for this age group based on the recommendation published by the Food and Agriculture Organization (FAO)/WHO.

Fortification procedure

After a number of studies, the vitamin A selected for fortification was retinyl palmitate 250 CWS (cold water soluble). This product, a gelatin microencapsulated preparation that contains 250,000 IU of vitamin A per gram and is water-miscible, is manufactured by Hoffman-La Roche in Basel, Switzerland, and BASF in Ludwigshafen, Germany. The fortification of a sugar premix is carried out in two steps. First, a concentrated premix is prepared containing, in addition to vitamin A, an unsaturated oil as a binder and an antioxidant to prevent peroxidation of the oil. The concentration of vitamin A in the premix is 1,000 times that of the final fortified sugar, which must be diluted with more sugar up to 1,000-fold. The premix is formulated to contain a 10% excess of vitamin A to correct for possible losses during the process. Then, the premix is diluted with sugar to attain the proper concentration of vitamin A. The original premix used in Guatemala had the composition shown in table 1.

To facilitate the preparation of the premix, a special mixer was designed to incorporate in the chassis the mixer, an oil depot with a heater, and a nitrogen bubbler. The horizontal axis of the mixer is hollow to allow the oil in the depot to be added directly to the mixer through sprayers. The principal section of the machine is a Y mixer with charging and discharging gates that rotates on a horizontal axis supported by ball bearings. The horizontal axis that goes through the mixer rotates in the opposite direction to the mixer itself in order to facilitate the addition of the antioxidant solution, thus ensuring a homogeneous mixture. The design of this machine is illustrated elsewhere [8].

The vitamin A and the sugar are placed into the mixer in the prescribed amounts and mixed for about 5 minutes. During this time, the necessary amount of antioxidant wax is dissolved in the oil, which is heated to 60°C. While dissolving, the antioxidant-oil mixture is maintained under a continuous stream of nitrogen. Once the wax is dissolved, it is flushed, while the mixer is still running, through the horizontal axis sprayers. Mixing is continued for 10 to 15 minutes, or until the mixture is homogeneous. The antioxidant-oil mixture is added through the sprayers to ensure a homogeneous mixture. After homogeneity is achieved, the premix is ready to be packaged until use. For packaging, a double black polyethylene bag is suggested, which, in turn, is placed inside another bag made of polypropylene fibres. The bag is hermetically sealed, taking care to exclude any trapped air. Using the described set-up, a single operator can produce one batch of premix in 10 to 15 minutes. It is also suggested that the premix bags have a printed label clearly stating that the premix is not for human consumption and indicating the date of preparation and the lot number. The vitamin A content of each lot should be checked analytically. The final product should be a slightly yellow, uniform, free-flowing mixture, with no agglomerations or impurities, slightly oily but with no rancid odour.

TABLE 1. Composition of the vitamin A-sugar premix originally used in Guatemala

Component	% (w/w)
Vitamin A palmitate 250 CWS	22.000
Peanut oila (peroxide free)	1.650b
Antioxidant (Ronoxan A)	0.008
Sugar	76.342
Total	100.000

a. The peroxide content of the selected oil must not exceed 5 mEq/L. The following oils have been tested and considered adequate: corn, palm, soya bean, cottonseed, and sunflower [7].

b. Specific gravity 0.61.

Premix stability

A premix prepared by the procedure described above and kept in a dry place shielded from direct sunlight should be stable for a period of time in excess of the turnover of the fortified sugar, which is produced in a cyclical process carried out each year during the same season. Figure 1 shows the half-life of premixes prepared in Guatemala and El Salvador under different environmental conditions. The premixes were prepared with sunflower oil in Guatemala and cottonseed oil in El Salvador. The minimum half-life of the premix is 2.8 years, well in excess of the mean turnover time of sugar. However, sugar is generally not stored for periods longer than one year.

Sugar fortification

The procedure for sugar fortification consists of diluting the premix with sugar in a ratio of 1:1,000, which can be performed at any of several points during production. The proper amount of premix can be added to the centrifuges in which crystallized sugar is separated, the conveyors that move the crystallized sugar from the centrifuges to the dryers, or the rotating drum dryers to take advantage of the efficient mixing produced by the drying process [8]. Ideally, for accurate addition of the premix, a dosing machine, which has been properly calibrated to measure the correct proportions of premix and sugar and which stops automatically when there is no flow of sugar, should be used. Regardless of the point selected for addition of the premix, the mixing that occurs in the drying drums is enough to ensure the homogeneity of the fortified sugar. The drying process lasts for only short periods of time at temperatures below 80°C, so that the stability of the vitamin A in the fortified sugar is not affected. Once the sugar is fortified, it should be packed in containers that protect it from direct sunlight and excess humidity.

FIG. 1. Loss of vitamin A activity during storage of premixes prepared at two sites in Guatemala and El Salvador

In the plant, quality control of the process should be continuous, and samples should be periodically analysed. The frequency of analysis depends on the amount of sugar produced and should be determined on a statistical basis. For quality control purposes, a number of field analytical procedures have been developed and tested to enable analysis of vitamin A content in situ in 1 to 3 minutes [8].

Stability tests carried out in Guatemala and in Basel, Switzerland, showed that vitamin A - fortified sugar can be directly heated to 100°C for periods of up to 15 minutes with no appreciable loss of activity. Syrups containing 55% to 65% fortified sugar heated for 1 hour at 80°C have shown losses of vitamin A activity on the order of 10% to 15%. Similar losses were observed in jellies containing fortified sugar that were cooked for 1 hour. When fortified sugar is dissolved at low pH values of 2 to 8 and heated, the loss of activity may reach 52%. On the other hand, when fortified sugar is used in hot coffee or tea prepared with boiling water and kept at this temperature for 10 minutes, the activity loss is only 1% to 2%. Storage of fortified sugar in commercially used bags for home distribution for up to six months at temperatures of 22° to 35°C and humidity levels of 70% to 85% saturation had no significant effect on vitamin A activity.

The biological activity of vitamin A-fortified sugar, compared with the standard vitamin A preparation used in trials employing experimental animals, yielded the same results for both preparations. In these tests, vitamin A-depleted rats were fed diets containing either fortified sugar or pure vitamin A palmitate. Both treatments had a similar capacity to restore plasma and liver retinol levels [8,9].

Cost of fortification

Vitamin A palmitate accounts for up to 99% of the cost of the premix. At the present time, the estimated cost of the components of 1 kg of premix is approximately US$8.10. Thus, the added cost to the selling price of sugar is on the order of US$0.0081 per kilogram of fortified sugar.

In a meeting with representatives of the producers of vitamin A held in the Guatemalan offices of UNICEF, the manufacturers made a commitment to maintain the price of vitamin A, subject only to changes in the value of the US dollar relative to the Swiss franc. This agreement has resulted in only small fluctuations in the price of the vitamin A palmitate 250 CWS used in sugar fortification. The changes in the cost per kilogram of the vitamin over the last 24 years are presented in figure 2 [8].

Newer technologies for sugar fortification

The procedures described above for the fortification of sugar are based on technology developed in the early 1970s and modified as needed over the following years. Problems that are generally encountered with this technology relate to poor conditions of preparation of premixes, low-quality oils with a high content of peroxides, and poor storage of the fortified sugar. The result, in spite of the use of antioxidants, is the slow development of rancidity of the added oil.

Several approaches have been taken to solve this problem. When saturated oils that remain in liquid form at room temperature are used, the fortified sugar remains stable. The small amount (about 0.08 Hg/g) of saturated oil used as a binder in the fortified sugar does not have any negative nutritional implications. In many countries, this modification would be the best choice. A second approach involves using a dry mixing procedure in which no oil is used as a binder of the premix, thus eliminating the problem of peroxidation. This procedure is particularly useful when dealing with highly refined sugars. Several other binders are currently under investigation; one of the most promising seems to be micronized soluble polyvinyl pryrrolidonli.

Fortification of sugar with iron

The characteristics of sugar that make it a good vehicle for fortification led to trials of fortification with iron compounds. In Guatemala during the mid-1970s, a trial of fortification of sugar with NaFeEDTA was carried out. At the time, this compound appeared to be promising, showing an apparent absorption of 3% to 8%. Sugar was fortified by directly adding 1 g of the chelate per kilogram of sugar. The iron content of the NaFeEDTA was 13%, resulting in the addition of 0.13 mg of iron per gram of sugar. Considering the maximal absorption of 8%, the amount of absorbable iron present was 0.01 mg per gram of sugar. With a mean sugar consumption of 36 g per person per day, a contribution of about 0.37 mg of absorbable iron per day from sugar was possible. However, after four years of consumption of this fortified sugar in three selected communities, the change in iron nutrition was only marginal [10]. Furthermore, there was a significant increase in the urinary excretion of zinc, copper, and iron (table 2).

FIG. 2. Price of vitamin A palmitate 250 CWS from 1972 to 1996

The addition of NaFeEDTA to sugar resulted in an obvious change of colour, and the addition of NaFeEDTA-fortified sugar to foods, coffee, and tea also resulted in marked colour changes. Immediately after the addition of fortified sugar to coffee, the coffee turned deep blue. All these factors prevented the use of NaFeEDTA as a sugar fortificant.

More recently, a new tasteless chelate, in which iron is chelated with three molecules of glycine (iron tris-glycine chelate), has been used successfully to fortify sugar in Brazil where technology was developed for the industrial fortification of sugar. Iron-fortified sugar, using this compound, is now commercially available in Brazil [11]. With the tris-glycine chelate, there are no organoleptic changes, to the point that it can be used in highly refined sugar. No changes in colour are caused by the addition of this sugar to foods, including coffee.

In premixes containing oil prepared with the addition of NaFeEDTA, the maximum amount that can be used without adverse effects is 50%, and only through modification of the premix to contain 11% vitamin A for a final dilution of 1:500. Premixes of this type containing iron tris-amino chelate (FeAAC) can be prepared with a significantly lower iron content but can still maintain the same level of absorbed iron (table 3).

TABLE 2. Urinary excretion of iron, zinc, and copper after four years of consumption of sugar fortified with NaFeEDTA at a level of 1 mg/kg of sugar

	Urinary excretion of metal - mg/g creatinine (mean ± SD)
Community	Fe	Zn	Cu
Control	36 ± 18	6±10	3 ±13
Community 1	112±21	131 ±34	51 ± 17
Community 2	126 ±31	110±32	104 ± 36
Community 3	134 ±29	247 ± 59	41 ±20

In terms of the percent iron content and its bioavailability, it is apparent that the amount of absorbable iron cannot be increased with NaFeEDTA fortification, but with the tris-iron chelate, the premix iron concentration can easily be increased to provide 100% or more of the daily requirement of absorbable iron.

By taking advantage of the technology developed for the dry mixing of nutrients and sugar, double-fortified sugar has been produced using vitamin A palmitate 250 CWS and iron tris-glycine chelate. Approximately 30% of this chelate, which contains 20% iron, is absorbed. The chelate has a very low toxicity; its LD₅₀ in rats is 17.0 g.

Iron bis-glycine chelate has been successfully used for fortification of whole cow’s milk and corn and wheat flours. Field studies using milk fortified with 3 mg of iron from the chelate, without addition of ascorbate, have shown that up to 40% of the amino acid chelate is absorbed [12, 13]. Formal studies using water solutions of ⁵⁵Fe-labelled amino acid chelate proved that it is absorbed even better than the standard ferrous ascorbate, which was used as the absorption control, and that its absorption is regulated by the iron stores of the body [14].

Impact of vitamin A-fortified sugar on the population

In Guatemala the fortification programme was evaluated in its first phase in 1975, and it was shown that after 6 months of consumption of fortified sugar, there was a significant decrease in the prevalence of low plasma retinol levels, and after 12 months, the mean prevalence of these values in the population was below 5%.

TABLE 3. Comparison of premix compositions using NaFeEDTA and iron tris-glycine chelate, considering the iron content of each compound and the bioavailability of its iron

Composition		Premix FeNaEDTA (13% Fe)	Premix FeAACa (20% Fe)
Components (g/100 g)
	250 CWS	11	11
	Iron compound	50	12.5
	Peanut oil	1.65	1.65
	Ronoxan A	0.008	0.008
	Sugar	37.342	74.842
	Iron in premix	6.5	1.73
	Absorbable iron	0.52	0.52
Premix dilution		1:500	1:500
Absorbable Fe/g premix		5.2 mg	5.2 mg
Absorbable Fe/g sugar		14.4 mg	10.4 mg

a. Iron tris-glycine chelate.

Similarly, the prevalence of human milk samples with less than 20 mg of retinol/dl was reduced by 50% in comparison with the levels before fortification. Human liver samples obtained from autopsies of persons killed in car accidents also showed a significant improvement in vitamin A content [8, 9].

After the reinitiation of nationwide sugar fortification in 1988, the first 6 months of the programme were evaluated (from November 1988 to May 1989). A comparison of the effects on plasma retinol levels in 1- to 7-year-old children in 1975 with those measured in 1989 is shown in figure 3. In the second evaluation in 1989, the adequacy of liver vitamin A concentrations was evaluated using the relative dose-response test. The response at this time point was similar to that observed in the first evaluation 14 years earlier, demonstrating the reproducibility of the effects of fortified sugar [8]. It is clear that through consumption of fortified sugar, the vitamin A status of a population can be improved within a relatively short time.

Now that the technology for the double fortification of sugar with vitamin A and highly absorbable iron tris-glycine chelate has been developed, it would appear that the control of iron deficiency and of iron-deficiency anaemia is also within reach. To illustrate the effectiveness of the iron amino acid chelates, the prevalence of iron-deficiency anaemia was reduced in some Brazilian populations from 70%-80% to 10%-15% after six months of consumption of whole milk fortified with iron bis-glycine chelate [13]. Studies carried out by the Secretary of Health of the state of Sao Paulo showed similar results, prompting the state to enact legislation making iron bis-glycine chelate fortification of the fluid milk used in Public Health Programs mandatory [12].

The cost of milk fortification is so low (US$0.001 per litre) that similar programmes can be easily replicated in any population in which milk can be used as a vehicle for fortification. Wheat and corn flours have been fortified with bis-glycine chelate with similar results to those obtained with fortified milk. A number of different foods have been fortified with the chelated iron and are commercially available in Brazil, including sugar, milk, corn flour, wheat flour, cheese, yoghurt, cookies, and margarine.

FIG. 3. Effect of consumption of vitamin A-fortified sugar on plasma retinol levels of one- to seven-year-old children in Guatemala [8,9]

In the development of these fortification programmes, the Latin American Centre of Nutrition and Metabolic Studies (Centro Latinoamericano de Nutrición y Estudios Metabólicos, CELANEM) has changed the usual mechanism for their establishment. Industry was initially approached and, with CELANEM, developed the fortification procedures to be used. Once industry had been convinced that the quality of their products would not be altered and that they could effectively contribute to the solution of many public health problems, public health authorities were contacted and presented with ready-made solutions. All of the products described above were developed in this manner and are now available on the market. For example, milk has already been fortified in Argentina, Chile, Paraguay, Ecuador, Brazil, Colombia, Venezuela, and Mexico; it is available in Europe and will be fortified in the near future in China.

References

1. Cervinskas J, Mahshid L. Vitamin A deficiency: key resources in its prevention and elimination. The Micro-nutrient Initiative Information Paper, No. 1. Ottawa: Micronutrient Initiative, January 1996.

2. Suarez R, Phillips M, Sanghvi T, McKigney J, Marquez L, Wickham C, Fiedler J, Holley J, Vargas V. El costo y la eficacia de tres intervenciones para aumentar emo de vitamina A en Guatemala. Latin American and Caribbean Health and Nutrition Sustainability, March 1994.

3. Raphael A. Fortificación del azucar en Guatemala. Guatemala City: UNICEF, 1995.

4. McKingney JI. Intervention for the prevention of vitamin A deficiency: a summary of experiences. In: Underwood BA, ed. Nutrition intervention strategies in national development. New York: Academic Press, 1983: 363-84.

5. Food and Nutrition Board, National Research Council, National Academy of Sciences. Proposed fortification policy for cereal grain products. Washington, DC: National Academy of Sciences, 1974.

6. Food and Agriculture Organization/World Health Organization. Requirements of vitamin A, iron, folate and vitamin B₁₂. Report of a Joint FAO/WHO Expert Consultation. Rome: FAO, 1988.

7. Mejia LA, Pineda O. Substitución del aceite de mani usado para la fortificación de azucar con vitamina A, por otros aceites vegateles disponibles en Centroamerica. Arch Latinoamer Nutr 1986,36:127-34.

8. Pineda O. Towards the control of vitamin A deficiency in El Salvador. Guatemala City: UNICEF, 1995.

9. Arroyave G, Aguilar JR, Flores M, Guzman MA. Evaluation of sugar fortification with vitamin A at the national Level. Washington, DC: Pan American Health Organization, Scientific Publication No. 384,1979.

10. Viteri FE, Alvarez E, Pineda O, Torun B. Prevention of iron deficiency by means of iron fortification of sugar. In: Underwood BA, ed. Nutrition intervention strategies in national development. New York: Academic Press, 1983:287-314.

11. Name JJ. Food fortification with amino acid chelated minerals. Proceedings of the seminar on Food Fortification for Better Health held in Cairo, Egypt, 16 September 1995. Cairo: Ministry of Supply and Internal Trade, 1995.

12. Souza-Quiroz S, Almeida-Torres MA. Anemia carencial ferrorpriva: aspectos fisiopatologicos e experiencia corn a utilizacao do leite fortificado. Pediatria Moderna 1995;31(special issue).

13. Iost C, Name JJ, Jeppsen RB, Ashmead HD. Repleting hemoglobin in iron deficiency anemia in young children through liquid milk fortification with bioavailable iron amino acid chelate. J Am Coil Nutr 1998; 17:187-94.

14. Olivares M, Pizarro F, Pineda O, Name JJ, Hertrampf E, Walter T. Bioavailability of iron bis-glycine chelate. J Nutr 1997;127:1407-11.