AN INVESTIGATION OF THE PREVALENCE OF
VITAMINS B6, B12, C, AND FOLIC ACID
IN THE DIET OF A POPULATION WITH VITILIGO

Anthony Apuzzo
Sleepy Hollow High School
Sleepy Hollow, NY

Abstract

This study explored the amounts of vitamins B6, B12, C, and Folic Acid that were ingested through the fruits and vegetables in the diets of vitiligo patients as compared to the United States Recommended Daily Allowance. Of the fifty-five vitiligo patients who voluntarily completed the questionnaire, fifty-three were valid for use in the study. The study found that on average, vitiligo patients do not eat enough fruits or vegetables containing vitamin B6, but had well more than the Recommended Daily Allowance of vitamins C and Folic Acid. Vitamin B12 could not be analyzed in the study due to its extremely low occurrence in fruits and vegetables.

This study sought to determine if vitiligo patients ingest the Recommended Daily Allowance of vitamins B6, B12, C, and Folic Acid through fruits and vegetables in their diets. Previously, studies involving vitiligo have concentrated on treatments such as PUVA, a type of light treatment, topical steroids, surgery, depigmentation, and characteristics studies. The newest area of investigation in vitiligo research is with nutrition, where a relationship has been established linking vitiligo to the levels of the vitamins B6, B12, C, and Folic Acid in the bloodstream of vitiligo patients.

Vitiligo is a skin condition that depletes the skin of pigment, leaving milky-white spots in its place. It is an autoimmune disorder believed to be hereditary, though it has not been proven. It affects one to two percent of the world’s population, or forty to fifty million people, including one to two million in the United States. It affects equally individuals of all ethnic origins and both sexes. For more than half of all vitiligo patients, the disorder began before the age of twenty years (Lerner & Nordlund, 1978). The most common areas to be first affected by vitiligo are the hands, feet, arms, face, and lips, although vitiligo can begin on any part of the body. There are two main concerns with vitiligo. The psychological impact of the disfigurement, especially when the vitiligo involves exposed areas such as the face, hands, or sexual organs, can be sufficient to hamper performance in school or place of employment of the patient. Physically, the loss of pigment can lead to malfunction of the epidermis, or outer layer of skin, producing decreased protection from the sun. About forty percent of vitiligo patients have pigmentary abnormalities in the eyes, and five percent note some loss of visual acuity, poor night vision, or photophobia. The goals of therapy are to return normal function of the epidermis by restoring the melanocytes, which produce pigment, and to restore normal appearance for the patient to regain a normal role in society (Nordlund, Halder, & Grimes, 1993).

There is no universally effective treatment for vitiligo. Melanocytes, which produce pigment, have been determined to be absent in vitiligo lesions. It was previously under dispute whether the melanocytes were present but dormant or absent altogether (Le Poole, et al., 1993). This discovery has helped treatment studies focus on regaining lost melanocytes, as opposed to reviving dormant melanocytes.

One of the most common treatments, particularly for vitiligo that has just appeared or is spreading is the application of topical steroids. Otherwise, for children over two years of age and adults, the most common traditional therapy has been PUVA, an acronym for Psoralen Ultra Violet (A)rays. Through this treatment, patients are either given topical psoralens in the form of a cream, or oral psoralens in the form of a pill. They are then exposed to Ultra Violet (A)ray light. These sessions are repeated twice weekly. This treatment has proven unpopular due to the time commitment, usually 100 to 300 sessions, the high cost, the pain of the blistering that occurs, and the cosmetic effect of hyperpigmentation that occurs in the surrounding skin, highlighting the vitiligo spots. Nor has this treatment been universally effective. For some, no improvement is shown after the treatment, leading to decreasing popularity as other areas of treatment are being explored (Antoniou & Katsambas, 1992).

Another category of treatment is the surgical type. Areas of pigmented skin are harvested from a hidden area of the body, then moved to the depigmented areas. The minigrafts are taken in rows from the pigmented area, usually the hip or buttock, but are then spread out to cover the depigmented lesion. This treatment has proven effective for a select group of patients who have stable vitiligo and do not suffer from Koebner phenomenon, which is the depigmentation of new skin grown after a cut or burn (Boersma, Westerhof, & Bos, 1995). A second type of surgical treatment involves culturing the melanocytes to expand their potency before applying them to dermabraded skin (Löntz, Olsson, Moellmann, & Lerner, 1994).

A fourth treatment option, though usually reserved for those patients with greater than fifty percent discoloration, is complete depigmentation. Monobenzylether of hydroquinone (MBEHQ), which destroys melanocytes, is used as a depigmenting agent. This treatment is not recommended, due to the extremely high sensitivity to the sun experienced by the patient after treatment (Antoniou & Katsambas, 1992).

Studies concerning vitiligo have often concentrated on characteristics of a population with vitiligo. It has been found that many vitiligo patients have an association with other autoimmune disorders, such as thyroid disease, pernicious anemia, or rheumatoid arthritis. An even stronger relationship has been formed between vitiligo and a family history of autoimmune disorders. It has been determined that there is a discernible difference between two types of vitiligo: unilateral, which is characterized by a rapid spreading of the condition for the first few years after the onset, after which it stabilizes; and bilateral, where the vitiligo spreads slowly and steadily over many years. Patients with darker skin types are more likely to have unilateral vitiligo while lighter skinned patients are more likely to have bilateral vitiligo (Barona, et al., 1995).

The newest area of study is the combination of nutrition and vitiligo. It has been determined that there are four basic vitamin and mineral groups that make a difference in vitiligo patients: Folic Acid, which not only matters to overall health, but also effects the uptake of the other two groups, vitamin B6, B12 and C (Montes, 1997).

The most common of the vitamins linked to vitiligo is vitamin C, also known as ascorbic acid. Found mainly in citrus fruits, tomatoes, strawberries, cabbage, and potatoes, vitamin C has three main functions: to aid the intake of folic acid, to aid the intake of iron, and to help the production of melanin precursors. Vitamin C is therefore important to vitiligo patients because of their tendency to be deficient of iron and folic acid, and to help better produce melanin, which is the goal of the treatment (Montes, pp. 109-116, 1997).

The second group is the vitamin B12. B12 is indispensable for normal blood production and other important physiological functions. Links have been established between pernicious anemia and vitiligo, making vitamin B12 an even larger factor. Furthermore, it is known that the two substances, vitamin B12 and folic acid, require each other’s presence in biological reactions that will not proceed in the absence of either one. When reactions are accelerated by supplying one of the two vitamins, the supplies of the other are consumed and unless replenished the reaction will slow down and eventually cease (Montes, pp.117-128, 1997).

In treatment it has been shown that oral B12 is not effective due to the poor absorption of B12 through the small intestine. B12 tablets are still prescribed in treatment, for some B12 is better than none, but the majority of the vitamin is supplied through monthly intramuscular shots. Hypothyroidism, which is linked to vitiligo through its nature as an autoimmune disorder, hampers the absorption of vitamin B12. In recent studies, administration of vitamins C, B12, and folic acid has been more effective in children and young adults who have recently been diagnosed with vitiligo (Montes, pp.117-128, 1997).

A fourth vitamin, B6, has proven crucial for nutritional vitiligo treatment. The vitamin is essential to the immune system as a whole, and B6 deficiency is especially common in women taking oral contraceptives. It has been found that large doses of B6 either orally or intramuscularly have been beneficial to repigmentation of vitiligo spots (Montes, pp.141-146, 1997).

In a study conducted by Juhlin and Olsson in 1997, one hundred patients, 33 men and 67 women, were given tablets of vitamin B12 and folic acid to be taken twice daily for three months. A number of patients chose to expose themselves to sun during this time while others did not. The results were promising: fifty-two patients showed definite repigmentation, with the most successful group those between the ages to ten and twenty-five who had vitiligo for less than twenty years. The least successful group was those patients thirty-five to forty years old who had vitiligo between fifteen and forty years. The results were significant because they showed progress in an area of vitiligo treatment other than the traditional PUVA, steroids, or surgery (Juhlin & Olsson, 1997).

After compiling all his research, Dr. Montes noted that the most severe cases of vitiligo amongst his patients occurred in the patients with the lowest amounts more than one of the vitamins B6, B12, C, and folic acid in their blood. Dr. Montes attributed this shortage to the environment, for in Buenos Aires people simply do not eat green vegetables regularly. Nevertheless, Montes recommends a complete vitamin profile for each of his patients, since his research has shown that vitamin therapy, while it may not lead to complete repigmentation on its own, may aid other treatments in their effectiveness (Montes, 1997).

It was the combination of the studies conducted by Barona, et al. in 1995, Juhlin and Olsson in 1997, and Montes in 1997 that led to this study. The 1995 Barona et al. study contributed an example of a characteristics study, which was particularly useful in devising the background questions for this study. The work of Juhlin and Olsson led to an increased importance of the vitamins B12 and folic acid, making them bigger factors in the study. Montes’ work was the main inspiration behind this study. A pioneer in the field, Dr. Montes has done extensive research, mostly in his native land of Argentina, finding an intimate relationship between the intake and absorption of vitamins B6, B12, C, and folic acid and the status of his vitiligo patients. His promising results with vitamin therapy led to many of the questions asked on the survey for this study. The aspect of his studies that separates them from this one is that they were conducted in an environment known for vegetable deficiency. Montes’ studies also were not of the eating habits of the patients, rather the results of those eating habits.

This study is centered on which fruits and vegetables vitiligo patients eat and how often they eat them. Although Dr. Montes’ work established a vitamin deficiency in a large population with vitiligo, that population was of one residence, a city notorious for not eating a complete diet. This study would then examine similar characteristics of a population known for eating a variety of foods that make up a complete diet. The study will further examine other characteristics of this population, such as overall health issues including exercise, smoking, and food allergies.

Hypotheses

1. Vitiligo patients are in good overall health: they exercise regularly, are conscious of their condition, and attempt to eat a well-balanced diet.
2. Vitiligo patients do not ingest enough fruits and vegetables to meet the Recommended Daily Allowance of the vitamins B6, B12, C, and folic acid.
3. If vitiligo patients do ingest sufficient amounts of the vitamins B6, B12, C, and folic acid through their diet, they may still be deficient in those vitamins due to poor absorption.

Methodology

Participants

Failed attempts to contact vitiligo patients through dermatologists led this researcher to the Internet to find a large group of patients. After speaking to several vitiligo patients through the Vitiligo LISTSERVE, found on the National Vitiligo Foundation website, (http://www.nvfi.org) the study was converted to HTML and posted on the World Wide Web at (https://www.angelfire.com/ny2/vitiligoresearch/index.html) and (https://www.angelfire.com/ny2/vitiligoresearch/questionnaire.html ) using Angelfire, a division of Lycos, Inc. The Internet address was distributed through e-mail to the Vitiligo LISTSERVE, or can be searched for on Altavista, Infoseek, MSN Search, and Excite. Being able to complete the survey without disclosing personal information such as a full name, address, or telephone numbers significantly improved the number of responses yielded.

This study included fifty-five vitiligo patients, thirty-five women and twenty men, ages four through seventy-seven. To be eligible for the study, the participant must meet three criteria: they must be currently diagnosed with vitiligo; they must be proficient in English or have a parent who is; and they must willingly complete the survey.

Procedure

A pilot study (N = 3) was administered to a small group consisting of one vitiligo patient and two test cases. Each participant completed the survey in less than twenty minutes, and their feedback was used to make any necessary changes to help the survey’s readability. The survey completed by the vitiligo patient was used in the study.

Various electronic mail letters were sent to the Vitiligo LISTSERVE, all with the same intention: please help a high school research student with his study by completing the questionnaire he has formed. By following the link in the e-mail, vitiligo patients were able to see an introductory letter prefacing the survey on their web browser. Following the link at the bottom of the page led them to the actual questionnaire, when they would highlight the survey, copy it, and paste it into an e-mail. The e-mail could be reached by selecting the link to this researcher’s address on that page. Once the survey was in the e-mail, all the patient needed to do was choose answers to the questions and send it to the researcher. A small number (N = 14) of the surveys were completed by hand. These surveys were sent by U.S. Postal Service or they were administered in person.

Convenience sampling was used in conducting this study. A patient’s participation depended on any of five factors: having access to a computer; having a working knowledge of computers; having contact with the Vitiligo LISTSERVE; having contact with somebody connected with the researcher; and being willing to complete a survey.

Instrumentation

Composition of Questionnaire The vitiligo patient questionnaire was divided into six parts. The first section addressed demographic information that included the patient’s age, date of birth, sex, height, weight, and ethnic background. The second section addressed the history of the patient’s vitiligo that included age at diagnosis, unilateral or bilateral vitiligo according to the definitions set by Barona, et al. in 1995, family history of vitiligo, and family history of other autoimmune disorders. The third section addressed types of past treatment. The fourth section addressed pertinent health characteristics of the patients. The fifth section addressed specific foods eaten by the patient the day prior to completing the survey. This section served to test congruency between the general eating habits described by the patient and the specific foods they ate yesterday. The final section addressed specific fruits and vegetables, asking the patients how often they ate any of the fruits and vegetables listed.

Investigation of Past Treatment Each vitiligo patient was asked if they had undergone any treatment for their vitiligo in the past year. If they had, they were asked which type of treatment they used: PUVA, steroids, skin graft, change in diet, or other. Those who chose other were asked to describe what type of treatment they tried. Regardless of type, patients who had undergone treatment were asked how they felt the status of their vitiligo had changed: no improvement, slight improvement, significant improvement, or complete repigmentation of vitiliginous lesions. The same set of questions was asked about treatments undergone prior to the past year. Patients who had received treatment within the past year did not need to answer the questions concerning previous treatment, regardless of whether or not they had undergone treatment prior to the past year. The issue was addressed to explore the combined effects of healthy eating with traditional treatments; treatments administered within the past year would take precedence over older treatments, making it unnecessary for those patients who fell into both categories to answer both sets of questions.

Health Issues Not Related to Specific Fruits or Vegetables Participants were asked if they regularly take vitamin supplements and if they do, how much of the vitamins B6, B12, C and folic acid are contained in their supplements. This question served to determine another source of vitamins other the listed fruits and vegetables listed later in the survey. The patients were asked if they are allergic to any foods and if so, which foods. This question served to identify one potential inhibitor of vitamin absorption. Patients were asked if they exercise and if they smoke and how often. These questions were to determine other health factors that may have an impact on the status of vitiligo in the patients. The patients were then asked if they eat red meat, other meats, eggs, and dairy products. For each of these four categories patients were asked to include how many times per week they eat foods of these categories, and which foods of these categories they eat most often. These questions were also to identify other possible sources of vitamins, as well as determine health factors that affect vitiligo.

Specific Fruits and Vegetables The survey included a list of sixteen fruits or groups of fruits and seventeen vegetables or groups of vegetables. The fruits and vegetables used in the study were determined using the Complete Book of Vitamins and Minerals, written in 1998 by Smith, McDonald, and Webb. The fruits and vegetables with the highest concentrations of vitamins B6, C, and folic acid as well as several commonly eaten fruits were included in the table where patients indicated how often they eat them each week, or if they eat them at all. The fruits used in the table are as follow:

The vegetables used in the table are as follow:

Data Analysis The data was analyzed by entering each answer for each question from the participants into a spreadsheet on Microsoft Excel. Percentages for each category were taken out of fifty-three, the number of surveys used in the study. For the individual vitamin values on the tables of fruits and vegetables, the Recommended Daily Allowance (RDA) was multiplied by seven to determine the Recommended Weekly Allowance (RWA) for each age group and sex. Vitamin values for each fruit and each vegetable used in the survey were found in the Complete Book of Vitamins and Minerals, written in 1998 by Smith, McDonald, and Webb. These vitamin values, measured in milligrams for B6, B12, and C, and in micrograms for folic acid, were multiplied by two, three, five, and six depending on the range selected by the participant. Once a listing of fruits and vegetables was assigned vitamin values for a patient, the values were added up to determine a minimum and a maximum vitamin intake according to the fruits and vegetables listed. These numbers were then divided by the Recommended Weekly Allowance and multiplied by 100 to determine the percent of the RWA a patient ingests through their fruits and vegetables weekly.

Results

Participants

Of the fifty-five surveys that were returned to the researcher, two surveys were ineligible for inclusion in data analysis. Studies were discounted if not enough information was supplied concerning the eating habits of the patients. Omission of questions regarding family history, age at diagnosis, ethnicity, previous treatments, amounts of specific vitamins taken through supplements, exercise, smoking, and food allergies were tolerated since they did not directly relate to the hypotheses being explored. Thirty-four females and nineteen males were included in the study. Table 1 represents the age breakdown of the participants according to the Food and Nutrition Board, National Academy of Sciences – National Research Council Recommended Dietary Allowances, found in the Complete Book of Vitamins and Minerals, written in 1998 by Smith, McDonald, and Webb. Table 2 represents the ethnicity as reported by the participants.

Table 1, Age by USRDA Ranges

Table 2, Ethnicity

Table 3 shows the number of participants who were diagnosed with vitiligo under the age of ten, under twenty, and under forty. These intervals were taken from an article written by Nordlund, Halder, and Grimes in 1993. The table also shows the type of vitiligo, unilateral or bilateral, of the patients, which was taken from an article written by Barona, et al. in 1995. The family history questions were part of several recent studies (Lerner & Nordlund, 1978; Nordlund, Halder, & Grimes, 1993; Barona, et al., 1995).

Table 3, Age at Diagnosis, Type of Vitiligo, Family History of Vitiligo and Other Autoimmune Disorders

Table 4 shows the number of participants who had attempted treatment either in the past year or prior to the past year.

Table 4, Past Treatment

The fourth section of the survey consisted of questions dealing with general health by way of vitamin supplements, food allergies, exercise, smoking, eating red meat, eating other meat, eating eggs, and eating dairy products. The results are shown in Table 5.

Table 5, Vitamin Supplements, Food Allergies, Exercise, Smoking, Eating Red Meat, Eating Other Meat, Eating Eggs, and Eating Dairy Products

The main part of the study, which investigated the second part of the hypotheses, dealt specifically with fruits and vegetables and how often the participant eats certain fruits and certain vegetables. Each participant responded to each fruit and each vegetable by choosing one of the following: 0 times/week, 1-2 times/week, 3-5 times/week, 6+ times/week. Unless the choice was 6+ times/week, any participant who ate a particular fruit or vegetable chose a range, which resulted in a minimum and a maximum value for each vitamin, except vitamin B12, which was not found in any fruits or vegetables, discounting it from the study. Table 6 shows the Recommended Weekly Allowance of vitamins B6, B12, C, and folic acid for thirteen different age and sex groups. The average vitamins ingested through fruits and vegetables for the entire study are as follow in Table 7.

Table 6, Recommended Weekly Allowances

Table 7, Average Percentages of RWA of Vitamins B6, B12, C, and Folic Acid

Conclusions

According to the data collected through this study, the first hypothesis can be accepted in its entirety. The first hypothesis was: Vitiligo patients are in good overall health: they exercise regularly, are conscious of their condition, and attempt to eat a well-balanced diet.

When asked “Do you exercise or play sports?” fifty-two of the fifty-three participants reported having some sort of exercise, with forty-two of them choosing “yes” as opposed to “sometimes” (Table 5). Other responses contributed to the conclusion that vitiligo patients are conscious of their condition: only three participants responded that they smoke. One of those three smoking participants reportedly smokes less than one cigarette per week. Just over half the respondents had undergone some sort of treatment for their vitiligo within the past year, with another 24.5 percent receiving treatment prior to the past year. Frequent exercise, abstaining from smoking, and seeking treatment all lead to the conclusion that vitiligo patients, at least the vitiligo patients in this study, are conscious of their appearance, proving the second section of the first hypothesis. The third section of the first hypothesis can be seen through part of the results shown in Table 5. Over eighty percent of the participants reported eating a balance of eggs, dairy products, and non-red meat during a week, as well as fruits and vegetables daily. On top of eating a variety of foods, just over half the participants reported taking some sort of vitamin supplements regularly.

The second hypothesis stated: Vitiligo patients do not ingest enough fruits and vegetables to meet the Recommended Daily Allowance of the vitamins B6, B12, C, and folic acid. Of the four vitamins under examination, B12 must be dismissed from this study because the only sources of vitamin B12 are animal products, which were not measured in this study. Of the remaining three, the hypothesis holds true for one. On average, a patient only ate enough fruits and vegetables to satisfy between 58.4 and 86.5 percent of the Recommended Weekly Allowance of vitamin B6. Coming up short of the RWA on this survey does not necessarily mean the patient is missing B6 in his or her diet, it means they are not getting all their B6 through fruits and vegetables. Animal products are very high in B6, adding a substantial supply to the body’s intake of B6. Vitamin supplements are another important source.

Vitamin C was ingested in greater amounts proportionate to the RWA than either B6 or folic acid. Ranging from 215.4 percent to 323.5 percent, vitamin C is clearly not compliant with the hypothesis. Yet despite the fact that vitamin C is ingested in such great amounts by the vitiligo patients in this study, the vitamin is often poorly absorbed by the patient. This idea will be explored further in the paper.

Folic Acid was also a contradiction to the hypothesis. While the minimum value was close to 100 percent of the RWA, the maximum value was 1˝ times the RWA. However, similar to vitamin C, folic acid is absorbed through the small intestine, which can become damaged easily from alcohol, aspirin, or birth control pills, leading to decreased absorption of folic acid. Folic acid is also closely connected with vitamin B12. Much of the folic acid contained in foods exists bound to amino acids. In order for the folic acid to be absorbed, it must be freed. Vitamin B12 helps to free folic acid from the amino acids (Smith, McDonald, & Webb, 1998).

The end conclusion of the study is that vitiligo patients appear to be in good overall health, and appear to eat a variety of foods that supplies them with most of the USRDA of vitamins. While they may eat enough foods with the vitamins B6, C, and folic acid, they do not necessarily absorb those vitamins. In order to determine if nutrition has a truly significant effect on vitiligo treatment, blood profiles for patients for patients need to be examined in addition to their diet. This third hypothesis was not addressed in this study due to the difficulty of obtaining blood profile information from patients.

Limitations

It is important to address the limitations of this study. The most prominent limitation is in the exclusive form of administration of the study. By collecting the majority of the sample through the Internet, the only group able to respond and participate was a group who had access to a computer, either at home or at work, knew how to use the computer, was a subscriber to the Vitiligo LISTSERVE, and had enough interest to complete a survey. Although this method produced a rather uniform study pool, it was the most practical method of distributing a survey to a large number of people who are not concentrated in one geographic location.

The study also did not take a complete look at the eating habits of vitiligo patients. The participants were only asked in detail about the fruits and vegetables they eat. The vitamins ingested through animal products or vitamin supplements were not carefully examined.

A third limitation on the study is that the actual amounts of vitamins being absorbed by the participants remain unknown. Simply ingesting the vitamin does not ensure it will enter the bloodstream. Many vitiligo patients have been found to be deficient in more than one vitamin despite eating a well-balanced diet of fruits and vegetables.

A fourth limitation to the study is the medium to which the vitamin intake of the vitiligo patients was compared. The values were compared to the Recommended Weekly Allowance, which is not necessarily the actual amounts of the vitamins ingested by the general public, meaning those without vitiligo. That population does not necessarily ingest the recommended amounts of vitamins, yet they are not afflicted with vitiligo.

Areas for Further Study

In future studies concerning vitamin intake and vitiligo three issues should be addressed: the sample, the range of foods studied, and the vitamins being absorbed instead of simply ingested.

In order to better generalize the entire vitiligo community, a larger sample should be taken, one including a larger variety of races and backgrounds. The study would have to include animal products to get a clearer idea of exactly how much B12 and B6 are being ingested. Thirdly, blood work would be necessary to see a vitamin profile for each participant. By looking at the amount of each vitamin in their blood, it would be known if the vitamin deficiency in the patient, if it exists, is caused by malnutrition or malabsorption.

References

Antoniou, C., & Katsambas, A. (1992). Guidelines for the Treatment of Vitiligo. Drugs, 43(4), 490-498.

American Psychological Association. (1994). Publication Manual of the American Psychological Association. Washington, DC: American Psychological Association.

Barona, M.I., Arrunátegui, A., Falabella, R., & Alzante, A. (1995). An Epidemiologic Case-Control Study In A Population With Vitiligo. Journal of the American Academy of Dermatology, 33, 621-625.

Boersma, B.R., Westerhof, W., & Bos, J.D. (1995). Repigmentation in Vitiligo Vulgaris By Autologous Minigrafting: Results in Nineteen Patients. Journal of the American Academy of Dermatology, 33, 990-995.

Juhlin, L., & Olsson, M. J. (1997). Improvement of Vitiligo After Oral Treatment with Vitamin B12 and Folic Acid and the Importance of Sun Exposure. Acta Derm Venereol, 77, 460-462.

Le Poole, I. C., van den Wijngaard, R. M., Westerhof, W., Dutrieux, R. P., Das, P. K. (1993). Presence or Absence of Melanocytes in Vitiligo Lesions: An Immunohistochemical Investigation. The Society for Investigative Dermatology, Inc., 100(6), 816-822.

Lerner, A. B., & Nordlund, J. J. (1978). Vitiligo What Is It? Is It Important?. Mournal of the American Medical Association, 239, 1183-1187.

Löntz, W., Olsson, M. J., Moellmann, G., Lerner, A. B. (1994). Pigment Cell Transplantation for Treatment of Vitiligo: A Progress Report. Journal of the American Academy of Dermatology, 30, 591-597.

Montes, L. F. (1997). Vitiligo Nutritional Therapy. Buenos Aires, Argentina: Westhoven Press. Nordlund, J. J., Halder, R. H., & Grimes, P. (1993). Management of Vitiligo. Dermatalogic Clinics, 11(1), 27-33.

Smith, S. M., McDonald, A., & Webb, D. (1998). Complete Book of Vitamins & Minerals. Lincolnwood, Ill: Publications International, Ltd.