I. Introduction
1. Yeast as food
Yeast is rich in B vitamins and in protein which usually are deficient in the diets of rice-eating people. The Food and Agriculture Organization of the United Nations has strongly recommended that its member countries, especially those in Asia explore the possibility of increasing the consumption of yeast in order to make up the deficiency in nutrition due to the practice of over-milling and over-consumption of rice. The FAO Nutrition Committee which met in 1948 at Baguio, Philippines, further suggested that the member countries adopt modern manufacturing methods to produce quality food yeast at low cost and initiate school-feeding programs to introduce yeast to people as a dietary supplement.
Yeast is familiar to the people in Taiwan as a drug for curing indigestion, stomach trouble, and beriberi. "Wakamoto," the trade name of a Japanese-manufactured yeast product, has been popular and for a time was regularly imported. The conception of yeast being a drug and its high selling price in the market, however, have caused people to refrain from consuming it as a daily food supplement.
2. Yeast production and composition in Taiwan
Toward the end of World War II, substantial quantities of Brewer's yeast, a by-product of alcohol manufacturing, was produced in Taiwan. The production of food yeast by Taiwan Sugar Corporation (TSC), a government owned corporation handling the production and processing of sugar cane and the international marketing of its products, was greatly increased in recent years as shown in the following:
| Year | Production (metric ton) |
| 1946 | 55.67 |
| 1947 | 24.55 |
| 1948 | 26.03 |
| 1949 | 16.15 |
| 1950 | 61.25 |
| 1951 | 84.79 |
| 1952 | 145.61 |
| 1953 | 278.74 |
| 1954 | 723.46* |
| 1955 | 1,002,551 kg. |
| 1956 | 2,326,746 kg. |
| *Including yeast for hog feed | |
The production of yeast by TSC are increased further by a project started in FY 1954 with U.S. Government financial assistance. As a result the TSC Hsinying Alcohol Plant will be converted into a yeast plant with a production capacity of 40 metric tons per day.
The TSC's food yeast production utilizes molasses, an important by-product of sugar manufacturing, as the basic material supplemented with nitrogen and phosphorus elements. The operation is under the direction and supervision of qualified technicians employing modern techniques and devices. The yeast so produced is comparable in quality with the yeast of the same strain, namely Torulapsis utilize, produced in other places.
The following table shows the composition of food yeast produced in Jamaica, Hawaii, and Taiwan:
| Jamaica (1) | Hawaii (1) | Taiwan (2) | |
| Moisture | 7.74% | 2.21% | 6.45% |
| Crude protein | 46.70% | 51.20% | 45.60% |
| Crude fat | 5.82% | 4.90% | 1.77% |
| Crude fiber | 6.16% | (3) | 2.34% |
| Crude ash | 7.66% | 9.28% | 7.84% |
| N-free extract | 33.60% | (3) | 34.91% |
| Vitamins (mg. per 100 gram) Thiamin Riboflavin | 0.99 | 0.96 | 0.866 |
| Microbiological | 3.98 | 7.82 | (3) |
| Fluorometnc | 3.97 | 7.91 | 4.75 |
| Biotin | 0.34 | 0.34 | (3) |
| Niacin | 40.2 | 37.9 | 42.2 |
| Pantothenic acid | 5.08 | 3.07 | (3) |
| Pyridoxine, HCI | 4.33 | 4.21 | (3) |
| (1) Industrial and Engineering Chemistry, Vol. 42, No. 9, Page 1830, 1950. | |||
| (2) Analysed by the Bio-chemistry Department of National Defense Medical Center in Jun 1953. | |||
| (3) Not determined. | |||
II. Yeast Feeding Demonstration
1. Pre-project investigation
Being predominantly considered a drug instead of a food, yeast has a very limited market on Taiwan. TSC has had difficulty in disposing of its production, although from a nutritional point of view it is much needed by the people. The Provincial Department of Education (PDE) with the assistance of JCRR has in the past three years endeavored to improve the health of school children. Several activities have been undertaken, including the correction of physical defects, eradication of parasites, periodic recording of students' body weight and height, and the training of school nurses. The schools and teachers are generally conscious of the importance of health and nutrition education work and are willing to cooperate in related action programs.
2. The feeding demonstration
The demonstration was carried out under the joint sponsorship of the Taiwan Sugar Corporation, which contributed 9,000 kilograms of yeast and the Provincial Department of Education (with the cooperation of the Education Bureau of Taipei Prefectural Government) which as the Executive Agency was responsible for the implementation of the program. The Joint Commission on Rural Reconstruction gave financial and technical assistance.
The demonstration was divided into two phases by the intervention of the summer vacation.
a. SELECTION OF SCHOOLS
Schools usually are widely dispersed with different geographical, professional and economic backgrounds. Strictly speaking no one is identical in background with another. The selection of comparable schools, one to consume yeast and another to be used as a control, with similar, if not identical, environments required much analytical work.
b. DISTRIBUTION OF YEAST
Yeast was factory packed in 5-gallon tins and transported from the TSC warehouse directly to the different participating schools on a monthly basis according to their actual requirements. The method of distribution of yeast to the students in Mushan Primary School was most commendable. Yeast of less than 5 grams was given to the students at one time. Yeast of 5 grams or more was given to the students in two batches: the first usually after the "morning health check-up" and the second at the first class period after lunch. Before the start of morning classes, the school nurse measured out the yeast according to the actual requirements of the respective classes [or the day. Yeast was then brought in small empty tins (used milk powder cans) to the different class rooms. The supervisors gave the containers to the students in the front seat of each row for distribution to the individual students. Each student received the yeast in a piece of clean paper folded in the form of a cone. He consumed it with a cup of boiled water which was provided from tea kettles by the students in the second seats of each row.
Although students were advised not to chew the yeast in order to avoid its sticking to the gums and teeth, many failed to follow the instruction. A slight irritation of the gums resulted in a few cases.
Every school, without fail stored the allocated yeast in proper places and disposed of it according to the instructions.
c. YEAST AS A DIETARY SUPPLEMENT
The protein and B-vitamin requirements of primary school students are comparable to those of the average adult. The inclusion of only 5 grams of yeast in the daily diet offers no appreciable increase in intake. However, if 15 grams per day is consumed, it contributes greatly to the rates of intake, as shown below:
| Age group (Ave. wt.) | Daily requirement | 5 grams of yeast | 15 grams of yeast | ||
| Amount | % of req. | Amount | % of req. | ||
| 4-6 years (19 kg) | |||||
| Protein | 50 gm | 2:28 gm | 4.56 | 6.84 gm | 13.68 |
| Thiamin | 0.8 mg | 0.04 mg | 5.00 | 0.13 mg | 16.25 |
| Riboflavin | 1.2 mg | 0.21 mg | 20.00 | 9.71 mg | 59.17 |
| Niacin | 8.0 mg | 2.11 mg | 26.33 | 6.33 mg | 79.13 |
| 7-9 years (26 kg) | |||||
| Protein | 60 gm | 2.28 gm | 3.80 | 6.84 gm | 11.40 |
| Thiamin | 1.0 mg | 0.04 mg | 4.00 | 0.13 mg | 13.00 |
| Riboflavin | 1.5 mg | 0.24 mg | 16.00 | 9.71 mg | 47.33 |
| Niacin | 10 mg | 2.11 mg | 21.10 | 6.13 mg | 63.30 |
| 10-12 years (35 kg) | |||||
| Protein | 70 gm | 2.28 gm | 3.26 | 6.84 gm | 9.77 |
| Thiamin | 1.2 mg | 0.04mg | 3.33 | 0.13 mg | 10.83 |
| Riboflavin | 1.8 mg | 0.24 mg | 13.33 | 0.71 mg | 39.44 |
| Niacin | 12 mg | 2.11 mg | 17.58 | 6.33 mg | 52.75 |
| Using NRC'S Recommended Daily Dietary Allowances. revjsed in 1948, as standard | |||||
Assuming that the average daily consumption of polished rice by a child of 10 to 12 years is 300 grams and is supplemented by 15 grams of food yeast, the intakes of protein and B vitamins are still below the actual requirements and should be supplemented by other sources. Nevertheless, the yeast greatly boost the riboflavin and niacin intake levels. The following shows the quantities of protein and B vitamins provided and the percentages of the daily requirements:
| Item | 300 grams of rice | 15 grams of yeast | Total | |||
| Weight | % of req. | Weight | % of req. | Weight | % of req. | |
| Protein | 21.1 gm | 28.71 | 6.84 gm | 9.77 | 26.94 gm | 38.49 |
| Thiamin | 0.36 mg | 30.00 | 0.13 mg | 10.83 | 0.49 mg | 40.83 |
| Riboflavin | 0.18 mg | 10.00 | 0.71 mg | 39.44 | 0.89 mg | 49.44 |
| Niacin | 4.5 mg | 37.50 | 6.33 mg | 52.75 | 10.83 mg | 90.25 |
d. NO STRICT CONTROL IN THE FEEDING DEMONSTRATION
Although the schools and other concerned agencies and individuals were responsible and cooperative, many factors beyond their control greatly affected the experiment. These factors included dietary habits of the students, their general physical conditions, their home living conditions, outbreak of communicable diseases, prevalence of intestinal parasite. Such conditions varied from one area to another or even from one student to another. All these had a decisive influence on the general health and welfare of the students and influenced their body weights and height measurements. Some deviations in accuracy of weight and height recording were found among schools. The degree of sensitivity and accuracy of weighing scales used, the clothes worn during the check-ups, the weighing time (whether before or after the meal), and other factors varied in some instances from school to school, or from class to class. Therefore, in the strictest sense, the feeding more appropriately should be called a "demonstration", to introduce yeast to the schools, students and their families and to determine its general acceptability and value as a food supplement, rather than an "experiment" conducted under fully controlled conditions.
e. FIRST PHASE DEMONSTRATION
The first phase of the demonstration began on May 1, and ended in the middle of July 1953 due to summer vacation. The daily intake ranged from 1.5 grams to 15 grams per student. Records were taken and have been analyzed with the following results:
(1) Out of the 7 primary schools, 5 show favorable effects of yeast on the body weight of the students. The average weight increase of students fed with yeast for the 2½ months' period is 0.26 kilogram more than that of students not fed with yeast.
(2) The number of students and the increase and decrease of body weight of both the yeast feeding and the control groups are as follows:
| Month | Group | No. of students | Increase in weight | No change in weight | Decrease in weight | |||
| No. of students | % | No. of students | % | No. of students | % | |||
| May | Yeast | 9,273 | 5,918 | 63.82 | 314 | 3.39 | 3,041 | 32.79 |
| Control | 9,029 | 4,789 | 53.04 | 391 | 4.33 | 3,840 | 42.63 | |
| June | Yeast | 9,274 | 4,048 | 43.65 | 168 | 1.81 | 5,058 | 54.54 |
| Control | 9,028 | 2,687 | 29.76 | 458 | 5.07 | 5,883 | 65.16 | |
| July(half month) | Yeast | 9,276 | 4,715 | 50.83 | 708 | 7.63 | 3,853 | 41.54 |
| Control | 9,028 | 3,662 | 40.56 | 1,051 | 11.64 | 4,315 | 47.80 | |
The difference in percentage of weight increase between the feeding and control groups, although amounting to only 10 percent, is statistically significant. However, the result cannot be considered as conclusive due to the following reasons: (1) The record of body weight has not been accurately taken by some schools; (2) It has not been possible to select two identical schools for purposes of comparison because different localities have different environments; (3) The general rice shortage during the first half period of the demonstration has affected the basic food supply in some poorer areas, such as Kungliao and Shuangchi in Taipei prefecture; (4) The daily intake of yeast of 5 grams per person as a source of protein is not sufficient for the purpose; (5) Besides B vitamins and protein, calcium may be another limiting factor of children's growth; and (6) The presence of intestinal parasites in the students may reduce the effectiveness of yeast.
f. SECOND PHASE DEMONSTRATION
The second phase demonstration was started on September 1, 1953 and ended on January 31, 1954 when the fall term was finished, lasting a total of 5 months.
(1) The outstanding features of the demonstration were:
(a) The introduction of different rates of daily yeast intake to one school: Because of the delay in reporting the actual number of students attending the fall term by the various schools, the yeast intake rate of the first phase demonstration was followed for the first one and half months. Beginning October 16, 1953, different daily intake quantities were introduced in one school so that a comparison among the students receiving different amounts might be made among the classes of the same school. It was thought that students in the same school would have a more or less similar environment.
(b) The introduction of yeast-bone meal tablets: As the daily calcium intake of children on Taiwan is usually low as the result of the low consumption of dairy products, the deficiency in calcium was also considered as one of the possible factors limiting the children's growth. A cheap source of calcium is from bone meal which contains about 37 percent of calcium (as CaO). Therefore, the TSC was requested to supply 2 tons of calcium-yeast, 1 ton of yeast mixed with 10 percent of bone meal and 1 ton of yeast mixed with 20 percent of bone meal. The mixing of bone meal in the yeast tablets was also expected to remove the gum-sticking effect of pure yeast tablets. The calcium-yeast was supplied in mid-November and regularly fed to some groups of students from December 1, 1953.
(c) The eradication of intestinal parasites: It was generally felt that the presence of intestinal parasites in some students would have an adverse effect on the effectiveness of yeast. In late November, 1953 the eradication work was carried out in some schools in order to compare "parasite-eradicated" and "non-parasite-eradicated" groups. Santonin (¼ grain)/ calamel (¼ grain) tablets were given in the following doses:
| Age (years) | Dosage |
| 6-7 | ½ tablet two times in three days |
| 8-10 | ⅔ tablet two times in three days |
| 11-12 | 1 tablet two times in three days |
(d) Clinical examination of selected groups of participating students: At the end of the yeast feeding demonstration, a clinical examination team, consisting of 3 medical doctors, 1 technician, and 1 supervisor, was sent to different schools to conduct physical examinations of the participating students. The items of examination included the general health condition, body height, body weight, and chest measurements, hemoglobin test, the development of bones and teeth, and tests for Vitamins B1, B2, and niacin deficiencies. About 5,000 students were examined.
(2) The results of the second phase demonstration are as follows:
| Group | Daily yeast intake | School | No. of students | Period | Body weight | ||||
| Total increase | Monthly average | Increase | No change | Decrease | |||||
| Yeast | 2 gm | San-kwang | 1,748 | 5 months | 1.49 kg | 0.30 kg | 52.10% | 37.75% | 10.15% |
| Control | 0 | San-chung | 2,378 | 5 months | 1.22 kg | 0.24 kg | 47.37% | 39.60% | 13.03% |
(a) Yeast group vs control group: The following comparison shows the results at two schools being located in the same general area and having students with comparable backgrounds.
The groups with a shorter feeding period showed a comparatively higher increase than those with a longer feeding period, which indicates that the effect of yeast consumption during the first month or two was more pronounced than that of the subsequent months.
(b) Groups with different yeast intakes in the same school:
| School | Yeast intake (gm) | No. of students | Period (months) | Body weight | ||
| Total increase (kg) | Monthly average (kg) | Percentage showing increase | ||||
| Panchiao | 3 | 890 | 5 | 1.2 | 0.24 | 52.49 |
| 5 | 612 | 5 | 1.57 | 0.318 | 56.29 | |
| 7 | 67 | 5 | 1.94 | 0.388 | 56.52 | |
| 10 | 135 | 5 | 1.51 | 0.302 | 70.96 | |
| 15 | 125 | 5 | 1.75 | 0.35 | 76.87 | |
| Mushan | 3 | 498 | 4 | 1.03 | 0.258 | 71.12 |
| 5 | 58 | 2 | 0.52 | 0.26 | 86.09 | |
| 7 | 94 | 5 | 1.85 | 0.37 | 65.11 | |
| 10 | 58 | 1 | 0.63 | 0.63 | 82.76 | |
| 15 | 104 | 5 | 1.55 | 0.31 | 71.98 | |
| Kungliao | 3 | 472 | 5 | 1.07 | 0.214 | 61.82 |
| 5 | 76 | 4 | 0.81 | 0.203 | 61.78 | |
| 10 | 993 | 4 | 1.01 | 0.25 | 65.68 | |
| 15 | 94 | 4 | 1.39 | 0.348 | 55.59 | |
(c) Calcium-yeast (bone meal as source of calcium) vs pure yeast:
| School | Yeast intake (gm) | Bonemeal content (%) | No. of students | Period (months) | Body weight | |
| Total increase (kg) | Monthly average (kg) | |||||
| Sanhsia | 5 | 10 | 112 | 2 | 0.85 | 0.425 |
| 5 | 20 | 112 | 2 | 0.6 | 0.3 | |
| 10 | 20 | 104 | 2 | 0.6 | 0.3 | |
| 15 | 10 | 215 | 2 | 1.06 | 0.503 | |
| 5 | 0 | 328 | 2 | 0.84 | 0.42 | |
| 10 | 0 | 211 | 2 | 1.01 | 0.501 | |
| 15 | 0 | 272 | 2 | 0.58 | 0.29 | |
| Panchiao | 3 | 20 | 615 | 2 | 0.53 | 0.265 |
| 5 | 10 | 65 | 2 | 0.63 | 0.315 | |
| 5 | 20 | 131 | 2 | 0.44 | 0.22 | |
| 10 | 10 | 111 | 2 | 0.8 | 0.4 | |
| 3 | 0 | 1055 | 2 | 0.49 | 0.245 | |
| Chichow | 5 | 0 | 1033 | 2 | 0.72 | 0.36 |
| 10 | 0 | 265 | 2 | 0.59 | 0.295 | |
| 5 | 10 | 1092 | 2 | 0.89 | 0.445 | |
| 5 | 20 | 1000 | 2 | 0.37 | 0.285 | |
| 5 | 0 | 985 | 2 | 0.75 | 0.375 | |
The calcium-yeast feeding experiment lasted for only 2 months from December 1, 1953 to January 1, 1954. The record reveals that an admixture of 90 percent yeast and 10 percent bone meal had a good effect on the weight increase of the students while a mixture containing 20 percent of bone meal had an adverse effect. The reason for this unexpected result was not ascertained.
(d) Effect of parasite eradication on students' body weight:
| Chichow | Sanhsia | Total or average | |
| No. of students participating in the eradication | 742 | 719 | 1,461 |
| No. of students discharging parasites * | 409 | 365 | 774 |
| Percentage discharging parasites | 55.12% | 50.76% | 52.98% |
| Average weight of participants before eradication (kg) | 22.99 | 23.17 | 23.07 |
| Average weight of participants after eradication 1 month (kg) | 23.44 | 24.14 | 23.79 |
| Increase within 1 month (kg) | 0.45 | 0.97 | 0.72 |
The big increase of 0.72 kgs in body weight within one month after the eradication of parasites shows that the presence of intestinal parasites is one of the factors retarding the normal growth of school-age children. The difference in increase between the Chichow student (0.45 kg) and Sanhsia student (0.97 kg) may be explained by the fact that people of Chichow, being closer to Taipei City, are more susceptible to attack by parasites through the consumption of vegetables fertilized with raw night soil from Taipei City, while people of Sanhsia, being a remote township, are less exposed. In both cases, the rate of increase was reduced for the following months.
(e) Clinical examination on symptoms of nutritional deficiencies. A total of 4,493 students of both yeast and control groups were examined shortly before end of the second phase demonstration, with the following findings:
| Group | School | Location | No. of students | % showing vitamin deficiencies | ||
| Vitamin B1 | Vitamin B2 | Niacin | ||||
| Yeast | Kungliao | Rural-mountains | 606 | 3.96 | 24.75 | 1.16 |
| Control | Shuangchi | Rural-mountains | 810 | 5.68 | 32.09 | 0.36 |
| Yeast | Mushan | Rural | 1263 | 4.99 | 31.35 | 3.01 |
| Yeast | Chichow | Rural-urban | 1465 | 12.97 | 28.55 | 2.87 |
| Control | Chungho | Rural-urban | 349 | 26.07 | 26.11 | 5.73 |
The physicians of the examination team were selected from general hospitals and were not highly specialized in clinical nutrition examination. Their judgment of deficiency symptoms might not coincide with others' findings. For example, the riboflavin deficiency of the students under examination was about 30 percent, while some nutritionists have reported it as high as 70 percent among the children of the primary schools in Taiwan. Nevertheless, the data are adequate for comparison.
(f) Reaction of students and their families: The reaction of students to the yeast feeding was carefully observed by both the school officials concerned and the project supervisors during the progress of the demonstration. Reports were received at the beginning that some students felt more thirsty while others felt nauseated. Some students complained that yeast caused a slight dizziness. Some students, mostly girls, with a high daily yeast intake were afraid that the yeast might not be properly digested and become harmful to their health. Nevertheless, the feeding continued and such complaints gradually were reduced, due partially to the formation of habit and partially to publicity and educational work. The students in the control group even complained against the unfair treatment of the project executor for not allocating yeast to them, and the students given small amounts of yeast were envious of their school mates who received 10 or 15 grams. About 98 percent of the students said that they liked yeast; many described the taste as being similar to that of parched peanut kernels.
Near the end of the demonstration, the responsible officials of Education Bureau of Taipei Prefectural Government interviewed individually several parents of the yeast feeding students. Thirty-two families in the vicinity of Panchiao were visited and a blank sheet of paper was distributed to each family, asking their comments. The points volunteered are tabulated as follows:
| Item | No. of families reported | % of total interviewed |
| Students' health improved | 25 | 78 |
| Students' appetite improved | 21 | 66 |
| Students rising earlier | 1 | 3 |
| More resistance to colds | 2 | 6 |
| More apparent effect observed | 2 | 6 |
| Program to be continued | 26 | 81 |
The favorable reaction from the students' families lends support to an expansion of the yeast feeding program in the future.
III. Recommendations
1. The production of yeast by TSC should be expanded and made efficient so that the price could be substantially reduced. Yeast would then be more acceptable to the people as a regular dietary supplement.
2. Research should be conducted and immediate action taken to prepare yeast in the form of food instead of as drugs so that people may consume it in large quantities instead of only a few "tablets." Research should also be done on introducing additives to enhance the taste and flavor so that the yeast can be used as a soup ingredient. For reducing the cost in packing, some material other than tin should be considered.
3. If the price is acceptable, yeast should be used to "fortify" or enrich wheat flour and sweet potato powder.
4. Research should "be made to increase the B-vitamin, especially" thiamin and riboflavin, and methionine contents of yeast. Deficiencies in thiamin and riboflavin are very salient among most rice-eating people.
5. Calcium-yeast should be widely produced for general consumption. The source of calcium may be common bone meal. If the required fineness and complete sterilization of bone meal could not be ensured, either calcium gluconate or ordinary limestone may be considered.
6. The yeast school feeding program should be continued and expanded. The daily yeast intakes for different age groups are suggested as follows:
6-8 years (roughly corresponding to grades 1 and 2): 5 grams
9-10 years (roughly corresponding to grades 3 and 4): 7 grams
11-12 years (roughly corresponding to grades 5 and 6): 10 grams
13 years and up (middle school students): 15 grams
The mixing of some 10 percent of bone meal or other calcium source in yeast for school children is recommended. This amount of calcium in yeast will supply about 40 percent of the minimum daily requirement.
7. Introduction of yeast to protein-deficient groups, notably the aborigines, the salt and mine workers, and farmers using sweet potatoes as their staple food, should be encouraged. The concerned agencies should work out practical plans to implement such programs.