The amount of protein one needs is less than that consumed in the SAD diet, but for those who want a dense vegan source of protein with a profile similar to the protein in animal products, yeast provides an option. Vegan bodybuilders and anyone desiring a little more protein could eat more nutritional yeast, which contains a whopping 70% of calories in protein, and the amino acid L-lysine closer to the proportions of animal protein than the level in plant protein.
The L-lysine from nutritional yeast can stimulate production of growth hormones that could lead to greater strength with exercise. But beware of supplementing large amounts of any individual amino acids such as L-lysine or L-arginine, since such supplementation can cause damaging imbalances.
Brewers’ and nutritional yeasts (saccharomyces cerevisiae) do not contain active B12 naturally. For nutritional yeast to contain active B12 it has to get added, as in Red Star’s “Vegetarian Support Formula”. However, it has not been established that enough B12 gets absorbed from “Vegetarian Support Formula” to provide for vegans’ needs.
In addition to taking B12 supplements, many vegans also eat nutritional yeast with their foods for the many B vitamins and other nutrients it contains beyond active B12 (if it is guaranteed to contain it). The B vitamins improve cellular oxygenation and energy production. Bs are also needed for robust digestion, immune function, red blood cell formation, and thyroid function. Simply supplementing B complex in addition to B12 also works.
Bakers’ yeast in pellets contains active although dormant yeast, so that bakers’ yeast undergoes a great deal of fermentation in the digestive tract. Nutritional yeast gets dehydrated and heated enough to deactivate the yeast. Therefore, nutritional yeast is preferable to bakers’ yeast.
Fortified yeast and supplements need to be protected from light since B12 is easily denatured by light.
Nutritional yeast, pumpkin seeds, beans and lentils, and fermented or sprouted grains are high in zinc (pg.447, Conscious Eating by Gabriel Cousens ISBN 1-55643-285-2). Further vegan sources of zinc include cooked legumes, wheat germ, fortified cereals, nuts, tofu, and miso.
Pantothenic acid (vitamin B5) is essential for coenzyme A, critical to energy metabolism. Pantothenic supports the adrenals for improved stamina. This vitamin also is reputed to help lower cholesterol. Vegan sources include nutritional yeast and mushrooms.
Gout is a form of arthritis caused by the accumulation of sharp painful uric acid crystals in joints, and sometimes in the kidneys (due to hyperuricemia). It’s possible that gout can result from reduced kidney function because of stress from a diet high in animal protein for example. Weakened kidneys cannot handle the load of uric acid concomitant with such a diet, so that the acid forms sharp crystals.
Nutritional yeast is high in purines as well as protein, as are animal products. Large quantities of yeast in the diet (greater than say 5 tablespoons) may provide too many purines, creating an abundance of uric acid, as with animal protein (Joanne Stepaniak, www.vegsource.com/talk/veganism). Even so, nutritional yeast doesn’t contribute to uric acid levels to the extent of animal protein, which contains not only purines, but also more uric acid and urea produced by the living animal. Uric acid and urea are primary solutes in urine.
I usually eat about 3 or 4 teaspoons of nutritional yeast for its B vitamins and protein, spread throughout the day. Eating more than 5 tbsp. per day raises concerns about getting too many purines from the yeast as one also can with animal protein.
Red Star’s “Vegetarian Support Formula” nutritional yeast contains human-active B12. I prefer the powdered form rather than the larger yellow flakes. A stale flavor of bulk-stored yeast indicates oxidation (denaturing and deactivation) of nutrients over long-term storage exposed to the atmosphere.
References follow for yeast recipes: The Uncheese Cookbook by Joanne Stepaniac (ISBN 0-913990-42-6) and The Nutritional Yeast Cookbook by Joanne Stepaniac (ISBN 1-57067-038-2). Personally I wouldn’t heat yeast beyond adding it to dishes after cooking.
Speculatively, eating more nutritional yeast with its high level of L-lysine could lead to more biosynthesis by the body of L-carnitine, taurine and creatine. So nutritional yeast can also be tried by those who are concerned about possible deficiencies in L-carnitine, taurine and creatine.
So far I’ve found only one report of the content in yeast of L-carnitine ("A biosynthetic role for carnitine in the yeast Torulopsis bovina" http://www.jbc.org/cgi/content/abstract/258/21/13160), a nutrient also found in animal products, and otherwise nearly missing in a vegan diet. (Please see “Conditionally essential supplements to the vegan diet”.) Depending on the growth medium, yeast can contain from 0.006 mg/100 gm to 22 mg/100 gm wet weight, about a fifth the content of L-carnitine in beef.
The standard growth medium for yeast is molasses enriched with bacteria that produce human-active B12, and probably also enriched with ammonia or various ammonium salts, phosphate in the form of ammonium or di-ammonium phosphate, calcium, magnesium, trace amounts of iron and zinc, and possibly other minerals. Oxygen gets provided in the form of filtered air. Since the standard growth medium demands metabolism of sugars for energy rather than metabolism of fats, I speculate that minimal L-carnitine gets biosynthesized by the yeast, since L-carnitine’s not needed for metabolism of sugars, so that nutritional yeast provides insignificant amounts of L-carnitine.
Nevertheless, yeast seems to me to be highly supportive of vigor, probably due to its high content of protein, B vitamins and other nutrients.
