Nutritional Yeasts and Yeastophobia, Part 2: An Interview with Dr. Jack D. Sobel

Whole Foods magazine

July 1999


Nutritional Yeasts and Yeastophobia, Part 2: An Interview with Dr. Jack D. Sobel

By Richard A. Passwater, Ph.D.

Anyone who has been involved in the natural products movement for any length of time knows of the important role that nutritional yeasts have played. First, baker's (brewer's) yeast was used as a powdered supplement to add to other foods. It usually was called brewer's yeast, but experts point out that it was actually a strain of baker's yeast. Baker's yeast was known to be a good source of the B-complex vitamins and a credible source of many minerals. Later, this nutritional yeast also was made available as tablets. Then, about 25 years ago, mineral-rich yeasts, such as high-selenium yeast, became available. Today, there are millions of people who benefit from nutritional yeast supplements.

I have been doing research with selenium since 1959 and have found most forms of selenium to be effective in reducing the incidence of cancer in laboratory animals. As far as I am aware, the only form of selenium that has been tested clinically is high-selenium yeast. In the December 25, 1996 issue of the Journal of the American Medical Association (JAMA), Dr. Larry Clark of the University of Arizona and his colleagues from several clinical centers published their results showing that high-selenium yeast cut the cancer death rate in half. Thus, many people prefer to use this proven form of selenium supplementation, now known as SelenoPrecise selenium yeast.

Meanwhile, I have witnessed a few store employees incorrectly warning potential purchasers of selenium yeast supplements that they should avoid yeast products. Some of the "reasons" that I have overheard are astonishing. This unfounded fear of nutritional yeasts is what I call "yeastophobia." After all, if yeasts are so harmful, what are they doing in health food stores?

As with most simplifications, when any large "family" of diverse entities is discussed as if all its members had identical properties, truth frequently is sacrificed. For example, today, "fats" are considered "bad," yet some fats are life-essential nutrients. It is more correct to consider some fats as "good fats" and other fats as "bad fats," although it is more accurate to consider fats in terms of balance and total quantity, as well as individual compounds.

Then, too, there are good germs and bad germs. Good germs? Yes, bacteria are called germs, and some bacteria are killers whereas others can help balance the population of bacteria in our gut so as to maintain a healthy gut environment. These "good" bacteria are called probiotics and have been a staple in health food stores for many decades. Yet, we don't shun people away from them because some bacteria can kill people

My concern is that, as future clinical studies add to the evidence that selenium is protective against many forms of cancer, more and more people will opt to take the actual supplement used in the clinical studies, selenium yeast. This is a logical choice and people shouldn't be confused by unfounded yeastophobia. Last month, I called upon yeast expert Dr. Seymour Pomper to discuss the differences between nutritional yeasts (Saccharomyces cerevisiae) and Candida albicans, a yeast that can cause infection. Now, I am calling upon Candida infection expert Dr. Jack Sobel, of Wayne State University and the Harper Hospital in Detroit, to discuss why nutritional yeasts are not involved in yeast infections and why Candida-infected persons should not go on "yeast-free" diets.

Jack D. Sobel is one of the world's leading researchers and physicians when it comes to Candida infections. He has published more than 117 peer-reviewed original articles and 65 review articles, including 76 articles on Candida. In addition, he has written or edited seven books and contributed 70 book chapters.

Dr. Sobel received his medical degree from the University of the Witwatersrand in Johannesburg, South Africa in 1965. He further trained as a resident in pediatrics and internal medicine at Johannesburg General Hospital, and then as a resident in cardiology and internal medicine at Rambam University Hospital in Haifa, Israel. He also was an assistant professor of medicine at the Technion School of Medicine in Haifa from 1973 through 1976. During 1976-1977, Dr. Sobel became a research fellow in infectious diseases in the Laboratory of Clinical Investigation at the National Institute of Allergic and Infectious Diseases at the National Institutes of Health (NIH) in Bethesda, MD. During 1977-1978, he was a fellow in infectious diseases at The Medical College of Pennsylvania in Philadelphia, PA. He then became an associate professor of medicine in the Division of Infectious Diseases at The Medical College of Pennsylvania. In 1985, he became professor of medicine at Wayne State University in Detroit in the Departments of Immunology and Microbiology, Obstetrics and Gynecology and Internal Medicine.

Dr. Sobel has received several awards including the "Best Doctors in America Award" in 1992, 1996 and 1998. lie is the associate editor of Infectious Diseases in Obstetrics and Gynecology, and serves on tire editorial boards of Sexually Transmitted Disease, Infection and Immunity, Mycology Review, Newsletter of Columbia University School of Public Health, and Scientific Studies of Alternative Medicine. He also serves as a reviewer for Many peer-reviewed medical journals, including the New England Journal of Medicine, Journal of infectious Diseases, Reviews of Infectious Disease, Annals of Internal Medicine, Infection and Immunity, American Journal of Medicine, American Journal of Obstetrics and Gynecology and Antimicrobial Agents and Chemotherapy. Dr. Sobel also is a consultant to the Centers for Disease Control and Prevention, Special Committee for Recommending Guidelines for Treatment of Sexually Transmitted Diseases.


Passwater: Dr. Sobel, its an expert in infectious diseases, with an emphasis on Candida-related illnesses, would you please explain what is meant by in) infectious disease?

Sobel: An infectious disease is any disease that is the direct result of an infectious microorganism, which can be a virus, a bacterium, parasite or fungus.

Passwater: Can you please explain what a pathogen is and how this would differ from an allergy or sensitivity? How does this term relate to the yeast strains of Saccharomyces and Candida?

Sobel: The word pathogen is a relative term and is basically an index, measurement, or expression of an organism's capacity to cause disease. A pathogenic microorganism is one that causes disease, whereas a non-pathogenic microorganism is one that doesn't cause disease. This is a little simplistic because under certain circumstances, such as when a patient's immune system is profoundly compromised; i.e. after a bone marrow transplant or cancer chemotherapy, many organisms that we traditionally consider non-pathogenic can become pathogenic.

To put this into perspective, Candida albicans, a very common organism, is one of the many pathogenic fungal species that frequently causes disease. When Candida albicans is introduced into the body of Normal healthy people. it is capable of causing disease.

In contrast, Saccharomyces cerevisiae is defined as non-pathogenic, meaning it very rarely causes disease. Over the past 20 years that I have been dealing with fungal infections diseases , Saccharomyces cerevisiae rarely has been associated with the cause of disease. In fact, 20 years I have seen only a half dozen cases of vaginitis caused Saccharomyces cerevisiae and only one or two cases of Saccharomyces causing infectious anywhere else in the body. Again the infections occurred only in profoundly immuno patients.

Saccharomyces cerevisiae is a classic example of a non-pathogenic, non-virulent, non-dangerous; non-disease associated microorganism or yeast, while Candida albicans is at the other end of the spectrum.

Passwater: In the few cases where you saw Saccharomyces cerevisiae cause disease, was the S. cerevisiae orally consumed, or did it enter the body by means other than this?

Sobel: The Saccharomyces that was associated with the disease was not related to its consumption. We eat and drink Saccharomyces cerevisiae all the time, and it doesn't cause disease.

Passwater: Candida is known to cause disease in humans. Please explain some of the factors related to Candida disease.

Sobel: Candida can cause two types of infections, either superficial or deep (invasive). Candida vaginitis is probably the most common clinical disease caused by Candida albicans. Candida vaginitis can occur in normal, healthy women. In contrast, Candida causing esophagitis or oropharyngeal candidiasis disease usually occurs only when people either are ill, have an underlying disorder or have taken antibiotics. These invasive forms of Candida infection almost always occur in people who are seriously ill.

Passwater: Are there other strains of yeast that are capable of causing infectious disease? Are you aware of molds being able to cause disease? Again, is Saccharomyces cerevisiae involved will the cause or the promotion of disease in either of these cases?

Sobel: First, by definition Saccharomyces cerevisiae is a yeast and not a mold. As Dr. Pomper discussed in Part I of this article (published in the June 1999 issue of Whole Foods), yeast and molds belong to the same kingdom of fungi, but they have many taxonomic differences and belong to different genera.

Candida albicans is only one specific species of Candida and yeast. Candida has many other species, and there are many other yeast-like structures that are capable of causing disease, particularly in patients whose immune systems have been compromised severely.

Molds can cause disease in a variety of different manners, from simple diseases like allergies to more severe deep infections. For example, you can be allergic to molds and inhale them, causing allergic rhinitis (the inflammation of the upper respiratory tract). Conjunctivitis inflammation of the conjunctiva or eyelid) and asthma are two other possible diseases related to mold exposure.

On a more serious note, molds can be extremely invasive and dangerous. There are many mold, capable of causing invasive disease in immuno compromised patients.

Passwater: How common are Candida diseases, and are these diseases limited to women or can they also affect men?

Sobel: Candida vaginitis is vary common. Between .50% and 70% of all women will get at least one case of this in their lifetime, and 50% of these women will have more than one episode. Candida vaginitis is very common. And it strikes many otherwise healthy women.

Candida albicans and other species of Candida can invade any tissue or structure, but there usually is some underlying abnormality. We do not see Candida infections at other sites within the body in otherwise healthy people. So, whether we are talking about the urinary tract, bones, joint infections, lung or brain infections, Candida only causes this form of invasive disease when the patient is profoundly immuno-compromised and usually hospitalized.

Passwater: How many cases of Candida related diseases do you see in a year?

Sobel: In a year, I see 200-300 cases of Candida vaginitis and another 30-50 cases of hospitalized patients with serious Candida infections. I see this large population of people with Candida infections due to the enormous amount of clinical experience our hospital has in dealing with fungal and infectious disease.

Passwater: In cases that you have been involved will], what is the most frequently seen disease associated with Candida?

Sobel: Candida vaginitis is the most frequently seen disease associated with Candida. As I mentioned previously, 70% of all women will have at least one case of this in their lifetime.

Passwater: Some women have more frequent problems with Candida vaginitis then others. What is the cause of this?

Sobel: This is very complex question. If you just take the entity called Candida vaginitis there are many forms. Mostly it is a sporadic, occasional infection in healthy women and may be caused by or related to the taking of antibiotics. Most of the time the attacks of Candida vaginitis occur without it recognizable precipitating event or cause.

In a subpopulation of women, probably 7%-8%, who get repeated episodes of Candida vaginitis, there is some evidence of a genetic predisposition. Also, there may be certain sexual behavioral factors that contribute to the infection and finally there is some evidence that the host's genital tract immune system may be impaired, thus predisposing her to repeated cases of Candida vaginitis.

Passwater: Are Candida-related illnesses becoming a chronic modern medical dilemma?

Sobel: I do not think this is true overall. While it is true that Candida infections are much more common today than they were previously, this is seen mostly in specific, susceptible groups, including hospitalized patients, those who are getting high doses of immuno-suppressants, individuals who have undergone complicated surgical procedures and those being kept in medical intensive care units. Candida also is a problem in people who have severely impaired immune systems, such as patients with AIDS.

However, outside the AIDS population and outside the hospital environment, in normal healthy people Candida vaginitis does not appear to be increasing in frequency. In fact, invasive Candida infections are rare in this population.

Passwater: Saccharomyces cerevisiae is the strain of yeast used in the nutraceutical market as well as for most industrial uses. The American Academy of Allergy and Immunology does not list or discuss allergies or diseases associated with Saccharomyces cerevisiae. Are you aware of any diseases caused by inactive S. cerevisiae? If so, are these common in society?

Sobel: As I have mentioned before, in my entire clinical experience 1 have seen just a handful of women with vaginitis caused by Saccharomyces cerevisiae. In these women the vaginitis was unrelated to the ingestion o1 Saccharomyces cerevisiae, and was probably related to manual transfer of the yeast into the vagina. These cases had nothing to do with the eating of Saccharomyces.

As far as Saccharomyces cerevisiae functioning as an allergen in the causation of allergic diseases, it is not considered an important allergen and is a very, very rare cause of any allergies.

Sobel: There is nothing rational about this belief. It is totally illogical. In the past few years, there have been a number of individuals and groups that have believed in the concept of "total body allergy" to Candida albicans. In this, they postulate that ingestion of Candida's as well as Candida's presence in the gastrointestinal tract in individuals who have received repeated courses of antibiotics, results in the overgrowth of Candida in the body. They further postulate that this overgrowth causes the suppression of the immune system, resulting in multiple symptoms within multiple organs.

Meanwhile, there is absolutely no objective evidence to support this belief. Members of the groups who advocate this theory based, on the overgrowth of Candida in the gastrointestinal tract, put the patients on "yeast-free" diets, and they recommend the use of oral antifungal agents as well. The result of this recommendation has been enormous confusion.

When patients are place on yeast-free diets, they frequently are told to go on diets that are low in Saccharomyces cerevisiae as well. This is irrational because there is no association at all between the presence of Saccharomyces and the presence of Candida. There is no association between Saccharomyces in the diet and systemic candidiasis.

Because of this mistaken extrapolation, many patients, particularly young women, have been given a "yeast-free" diet. This is a horrendous diet, and it is an extremely difficult diet to follow as a means of controlling a nonexistent or unsubstantiated clinical syndrome of chronic candidiasis.

I never put patients on yeast-free diets, as they are painful, non-nutritional, extremely difficult to comply with, and ill advised in my opinion. It will induce weight loss, however, because you end up eating nothing.

Passwater: It has been written that as many as one out of every three people (33%) say that they have a food allergy or modify the family diet because a family member is suspected of having a food allergy. The National Institute of Allergy and Infectious Disease has indicated that, as a result of specific diagnosis, only about 3% of children have clinically proven allergic reactions to foods. In adults this clinical level drops to about 1% of the total population. What do you think is the reason for the huge discrepancy between the perceived and clinical diagnosis?

Sobel: This question hits the nail on the head and addresses one of the largest and problems of practical medicine today, namely the practice of non-evidence-based medicine. This is where physicians without any data, without any support, without scientific information or confirmation are willing to postulate or hypothesize imaginary clinical syndromes according to a variety of whims.

We have not traditionally trained physicians or any other form of health care practitioner to function on any basis other than evidence-based medicine. In other words, diagnosis never is confirmed if there is no scientific or logical basis for the diagnosis. If there is no test that can be done to support the diagnosis, then everything is a matter of opinion and is done very superficially. This problem does not only pertain to allergies and infectious disease; it applies to all aspects of medicine.

The single most important advice one can give a patient is for him or her to demand from every practitioner that all treatments be based on confirmed, substantiated diagnosis.

Passwater: To reiterate, as an expert on Candida, do you believe there is a reason to prohibit yeast-containing foods from the diet for the clinical management of Candida infections?

Sobel: There is absolutely no logical reason to limit Saccharomyces cerevisiae from the diet. There is no clinical Support, and I strongly condemn this practice.

Passwater: Dr. Sobel, thank you for chatting with us about your specialty I hope that your comments help ease the growing fear of nutritional yeasts, when they have so much to offer. Nutritional yeasts have been a mainstay of the health food movement since its beginning, and nutritional yeasts will do much for the health of all people. WF



1999 Whole Foods Magazine and Richard A. Passwater, Ph.D.

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