Harnessing the Nutrients for Modern Use
Yeast microbes may be the earliest domesticated organisms. Since very early times humans have used yeasts for fermentation, one of the oldest and most successful methods of food processing and preservation. In addition to their importance in the preparation of foods and beverages, yeasts have many health benefits all their own. Today, dried and deactivated yeast products have become increasingly popular, due to the high levels of proteins and B vitamins they offer. In this article we will review the practice of incorporating nutritional yeast into the diet as a superfood supplement.
For millennia, societies worldwide have used yeast to create nourishing foods through the practices of baking and brewing. Evidence from Egyptian ruins suggests that yeast has been an important part of the human diet for at least four thousand years. Archeologists digging in ancient sites in Northern Africa have uncovered grinding stones and baking chambers for yeasted bread, as well as drawings of bakeries and breweries.1
DIFFERENT TYPES OF YEAST
It wasn’t until about one hundred fifty years ago, however, prompted by the work of Louis Pasteur, that scientists began to consider exactly how yeast works. Since that time, researchers have come to understand that yeasts do much more than contribute to the flavor and texture of foods. Dietary yeasts have many health-promoting effects; certain strains of yeast support the gut microbiome, enhance the immune system, act as anti-inflammatories, biosynthesize nutrients and increase the assimilation of vitamins and minerals.2
In recent years, the nutraceutical industry has sought to harness the beneficial properties of yeast for use in health-related products. Today, there are three main dried yeast products seen on the market: nutritional yeast, brewer’s yeast and baker’s yeast. All of these products are created using a species of yeast called Saccharomyces cerevisiae, which is the most common yeast for food and nutraceutical preparation.3 Unlike yeasts from the Candida genus, S. cerevisiae is non-pathogenic and does not cause or contribute to infection.
There are many strains of the S. cerevisiae yeast, which have been selected and evolved over generations for specific properties and uses. According to researcher Seymour Pomper, PhD, the strains of yeast used at present are direct descendants of the yeasts first introduced into the food industry in the U.S. more than one hundred years ago.4
This article focuses on nutritional yeast, a specific form of dried and deactivated yeast that is often used as a health food. Nutritional yeast is most widely known for its nutty or cheesy flavor, which lends itself nicely to a variety of savory dishes. Chances are you have strolled by bins of the golden-yellow flakes in the bulk aisle of your natural grocer before. You may also have found nutritional yeast bottled up as a seasoning or coating your favorite kale chip snack. Popularized during the 1970s, it can be enjoyed as a condiment, stirred into sauces, sprinkled over egg or veggie scrambles, mixed into cracker recipes, added to breading or used as a coating for popcorn. Those following a Weston A. Price-inspired diet may also recognize nutritional yeast as one of the key ingredients in the Nourishing Traditions homemade baby formula.
Beyond taste, nutritional yeast has an impressive list of health attributes. It is naturally rich in select B vitamins including B1 (thiamine), B2(riboflavin), B5 (pantothenic acid) and B6 (pyridoxine). These vitamins support the metabolism of carbohydrates, fats and proteins to provide energy for the body. They are also important for maintaining a healthy nervous system, aiding with vision, and enhancing the integrity of the skin and hair.5 In addition, nutritional yeast contains fifteen different bone- and muscle-building minerals, including iron, selenium, zinc and potassium. It is a good source of protein as well, meaning it offers a range of essential amino acids that our bodies don’t naturally produce.6
Nutritional yeast is often confused with brewer’s yeast, but the two are distinct. Brewer’s yeast is aptly named, as it was initially offered as a byproduct of the beer brewing industry. It is now found in dried and deactivated forms specifically prepared for use as a nutritional supplement. Supplemental brewer’s yeast, also called primary brewer’s yeast, is typically grown on a medium of corn or other types of grain. Brewer’s yeast is known for being high in protein, B vitamins and chromium, an essential trace mineral that helps with normalizing blood sugar levels. Because it has a bitter taste, however, brewer’s yeast is used less frequently in foods and is often found in tablet and liquid forms.5
Baker’s yeast is another form of granulated yeast that is used exclusively for baking items such as bread. Unlike dried nutritional yeast, baker’s yeast is carefully prepared and placed in light-protecting packaging so that the yeast strains remain active. When used in recipes, the yeast converts carbohydrates into carbon dioxide. It is this fermentation process that causes dough to leaven or rise. There are anecdotal reports suggesting that a tonic of active yeast and water or milk can be prepared and consumed to boost energy, but opinions on the health benefits of raw yeasts are mixed. Others have stated that consuming active baker’s yeast can deplete the body of B vitamins and select nutrients.7 There is limited scientific research on the subject, which is perhaps why most individuals opt to use deactivated forms of yeast when supplementing.
HOW IS NUTRITIONAL YEAST MADE?
Historically, yeast cultures have been made by mixing together a medium such as flour and water, and letting this starter sit out in open air to “capture” the wild yeasts naturally present in the environment. If you have ever worked with sourdough in your kitchen, you are familiar with this slow and rewarding process.
The steps for manufacturing dried nutritional yeast veer from traditional methods. Commercial nutritional yeast cultures are grown in large quantities and handled in tightly controlled lab-like environments. Temperature and pH are carefully adjusted to optimize the growing rate of the microorganisms. The strains are also closely monitored for quality, and strict measures are taken to prevent contamination. Once the growing of the yeast is complete, the cultures are dried to render them inactive. This step prevents the yeast from reproducing or fermenting, and also concentrates the nutrients. From here the yeast is rolled into flakes or pulverized into powder for bottling.
The current method for manufacturing nutritional yeast can be broken down into four main steps: seeding, cultivation, harvesting and drying.
This process provides a template for the production of nutritional yeast. There are significant variabilities based on manufacturer, however. Some companies take the additional step of fortifying the yeast to amplify the volume of naturally-present nutrients or to add other desired compounds. Select companies employ high temperature spray drying to dehydrate and deactivate the yeast product.
The methods used to manufacture nutritional yeast directly affect the quality of the final product. Below are some key factors to consider when selecting the best nutritional yeast.
HEATING AND DRYING METHOD
Nutritional yeasts are heated for two central purposes: to render the yeast strains inactive and to dehydrate the yeast into a powder that can be easily packaged and stored. Most yeasts are deactivated by the process of pasteurization. This method is questionable as many nutrients, including most of the B vitamins, are temperature sensitive. It is unclear how dramatically pasteurization alters the nutrient profile of the yeast.
Next, the yeast is dried. This occurs either by drum drying or spray drying, depending on the manufacturer. Drum drying involves drying the yeast at relatively low temperatures over rotating, high-capacity drums that produce fine sheets of dried material. These sheets are then milled into flake or powder form. Spray drying is a method used for instantly producing fine dry powder by rapidly drying the yeast with hot gas. Spray drying often causes thermal degradation, however, and is thus considered a poor method for producing nutritional yeast.
FORTIFICATION WITH NUTRIENTS
Many nutritional yeast producers add nutrients during the manufacturing process to create an impressive final vitamin and mineral profile. It is especially common for vitamin B12 to be added, since this vitamin is not naturally present in large amounts in yeast. Folic acid is another frequent additive. While certain strains of Saccharomyces cerevisiae do have the potential to biosynthesize folate, it is not often generated in significant quantities. Therefore, any time these nutrients—vitamins B12 and folate or folic acid— are present on nutritional yeast labels, it is fair to assume they have been added.
Some brands claim to use naturally derived nutrients for fortification, while others openly use synthetic compounds. Unfortunately the term “natural” is not regulated, making it difficult to assess the true quality of the fortifying nutrients without inside access to the manufacturing process. Currently there is only one major brand offering non-fortified nutritional yeast.
GENETICALLY MODIFIED ORGANISMS (GMOs)
Most nutritional yeast is grown on a medium of sugarcane and/or beet molasses. This is troublesome as sugar beets are a high risk crop for genetic modification. According to the researchers at the Non-GMO Project, 95 percent of the sugar beets grown in the United States in 2010 were either contaminated from or grown using genetically modified materials. It is thus important to check with manufacturers to question the medium used to grow nutritional yeast and to ensure that their products are free of GMOs.9 Some brands use organic ingredients for the growing medium, which is favorable for preventing contamination with GMOs.This having been said, no nutritional yeast producers have yet received official non-GMO certification.
The issue of monosodium glutamate, or MSG, in nutritional yeast is a sensitive one. Yeast-based products naturally contain glutamic acid, an amino acid that is found in abundance in plant and animal proteins. Glutamic acid and glutamate (its ionized form) are considered essential for life and are critical for gut, brain and immune health. Both are found in high amounts in traditional foods like bone broth, matured cheeses and cured meats. MSG on the other hand, is the isolated sodium salt of glutamic acid, which is a synthetically created compound used to enhance the flavor of processed foods.10 Both naturally occurring glutamate and MSG contain glutamic acid, but the compounds behave differently in the body. Nutritional yeast does not contain MSG unless it is added. Individuals who are sensitive to glutamate products, however, may opt to avoid nutritional yeast due to the inevitable presence of glutamic acid.
Nutritional yeast is a flavorful, convenient and nutrient-dense health food when grown and prepared properly. It is naturally high in protein, concentrated in certain B vitamins and rich with trace minerals. Unfortunately, some manufacturers provide adulterated forms of nutritional yeast that have been exposed to high heat and fortified with synthetic nutrients. It is therefore critical to monitor brands closely in order to select the best and most authentic product.
THE THREE MAIN TYPES OF YEAST
NUTRITIONAL YEAST: Deactivated yeast used as a condiment and nutritional supplement; known for nutty or cheesy
BREWER’S YEAST: Deactivated yeast that is a byproduct of beer-making industry or grown on grain; bitter taste
BAKER’S YEAST: Active yeast used to make baked goods; not produced for supplemental consumption
NUTRITIONAL YEAST PRODUCTION
1. SEEDING: A parent yeast culture is carefully prepared in flasks and sterile fermentation tanks.
2. CULTIVATION: The yeast culture is fed a glucose-rich medium such as beet sugar, molasses or sugarcane. The temperature and pH are also controlled to optimize growth.
3. HARVESTING: Once the growing process is complete, the fermented yeast liquid goes through a washing or centrifuging process to concentrate the yeast cells. The result is an off-white liquid or “nutritional yeast cream.”
4. DRYING: The nutritional yeast cream is heated or pasteurized to render the yeast inactive. Next it is dried on roller
drums and pulverized. The powder is now ready for packaging.
Adapted from LeSaffre, 20148
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2. Moslehi-Jenabian, S., Pedersen, L. L. and Jespersen, L. 2010. Beneficial effects of probiotic and food borne yeasts on human health.Nutrients 2(4):449-473.
3. Legras, J-L., Medrinoglu, D., Cornuet, J-M., and Karst, F. 2007. Bread, beer and wine: Saccharomyces cerevisiae diversity reflects human history. Molecular Ecology 16(10):2091-2102.
4. Passwater, R. A. 1999. Nutritional yeasts and yeastophobia: an interview with Dr. Seymour Pomper. Whole Foods Magazine. Available at: http://www.drpasswater.com/nutrition_library/Yeastophobia_Pomper.html.
5. UMMC. 2014. Brewer’s yeast. Complementary and alternative medicine guide. Available at:http://umm.edu/health/medical/altmed/supplement/brewers-yeast.
6. Oaklander, M. 2015. Should I eat nutritional yeast? Time Magazine. Available at: http://time.com/4016184/nutritional-yeast/.
7. Bruno, G. 2009. Nutritional yeast and liver. Huntington College of Health Sciences. Available at:http://www.hchs.edu/literature/Nutritional%20Yeast%20&%20Liver.pdf
8. LeSaffre Yeast Corporation. 2014. The 5 steps in manufacturing nutritional yeast. Available at: http://lesaffre-yeast.com/five-steps.html.
9. Non-GMO Project. 2011. Agricultural crops that have a risk of being GMO. Available at: http://www.nongmoproject.org/learn-more/what-is-gmo/.
10. Tapiero, H., Mathe, G., Couvreur, P., and Tew, K.D. 2002. Glutamine and glutamate. Biomedical Pharmacotherapy 56(9):446-57. Available at: http://www.ncbi.nlm.nih.gov/pubmed/12481981.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation,Fall 2016