Is Yeast Paleo?

March 27, 2012 in Categories: , by

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When I consider whether or not there is a place for a specific food in a paleolithic diet, I don’t think of whether or not cavemen ate that specific food.  Instead, I think in terms of healthy food versus foods that cause gut irritation and inflammation (see my post Is It Paleo?).  This question typically comes up when considering foods that don’t squarely fit into the meat, vegetable or fruit categories.  So when considering a food such as yeast (naturally occurring, but not “domesticated” until something like 9,000 years ago), I find myself scouring the internet and medical journals for information to answer:  what effect does this specific food have on our digestion, the integrity of our gut, hormone balance, and inflammation?  I tackled the question of yeast for two reasons:  some strains of yeast are very important for healing and restoring healthy microflora in our guts (and I’ve been very interested in gut health lately); and, I really really miss yeast-based bread. 

 There are many, many different kinds of yeast.  And it terms of our health, they fall into three categories:  beneficial, harmful, and neutral.  Let’s talk about harmful yeast first, the kinds that grow in your small intestine during Small Intestinal Bacterial Overgrowth and that cause yeast infections (vaginal yeast infections, jock itch, athlete’s foot, and thrush).  These yeast are typically in the Candida genus (you may have heard of the candida diet, which typically avoids all fermented, sugary and starchy foods).  These yeast cause inflammation and depending on where they are growing, can cause a lot of discomfort.  And if you have an external yeast infection, chances are really good that they are overgrowing in your small intestine as well.  If you are battling with candida, I recommend cutting out all sugary and starchy foods, and following the tips outlined in my post Repairing the Gut.

Now, let’s talk about beneficial yeast.  Yes, some kinds of yeast are a normal and healthy part of your gut microflora.  These yeast are typically from the Saccharomyces genus.  These yeast have been shown to have potent anti-microbial effects in the gut (they can reduce the growth of bad bacteria like Clostridium difficile) and to help reduce inflammation in the body.  In fact, Saccharomyces boulardii is even available in pill form as a probiotic supplement.  These yeast are typically found in fermented foods, such as kefir, kombucha and lacto-fermented vegetables likes sauerkraut.  Let’s also be clear:  eating foods that contain Saccharomyces boulardii or other beneficial yeast do not increase your likelihood of getting a yeast infection (a common misnomer).  In fact, eating beneficial yeast can help treat a yeast infection. 

No, cavemen did not ferment foods either as a form of preservation or to increase their dietary intake of beneficial bacteria and yeast.  The advent of fermentation came with agriculture.  But, probiotic bacteria and yeast were still part of the ancestral diet.  Before modern agriculture, pesticides, herbicides, clean water with which to wash our vegetables, before antibiotics for cattle and quality control for poultry feed, all food derived from plant and animal sources (um, is there any other kind of food?) contained naturally-occurring probiotics.  In fact, a great way to get beneficial yeast and bacteria into your diet is to grow your own vegetables organically and eat them without washing them first.  So, while our prehistoric ancestors did not consume concentrated sources of probiotic yeast, they had fewer challenges to their gut microflora (like antibiotics use, stress and high-sugar diets) and they did consume probiotics every time they consumed food.  Yes, yeast is paleo.


So what about Active Dry Yeast for baking bread?  Well, active yeast is the strain Saccharomyces cerevisiae.  This strain of yeast is found naturally in some kefir cultures and some lacto-fermented foods.  It is also the strain used to make wine and beer.  It is very closely related to Saccharomyces boulardi, although from my reading it doesn’t seem to possess the health benefits that Saccharomyces boulardii does.  After thorough research, I have come to the conclusion that Saccharomyces cerevisiae is, at worst, neutral.  So what does this mean?  This means that if you allow wine and gluten-free beer in your diet, or if you make your own coconut milk Kefir, there is no reason to avoid dry active yeast in your paleo baking.  So, dust off those Bread Machines because tomorrow I will be posting a recipe for yeast-based paleo bread! 




I don’t think I could love you any more than right now. If I can use yeast to make a passable bread – it’s like the holy grail!

What about nutritional yeast, the dairy-substitute of raw foodies everywhere? It can be used to make cheese-like sauces. Is it safe for the gut/immune system, too? What exactly is “nutritional yeast”?

Nutritional yeast is Saccharomyces cerevisiae that is grown feeding on molasses and then killed with heat and dried. I think it falls under the harmless category for most people.

I made a gluten free beer a couple years ago with honey for about 1/3 of the fermentables and it is quite good after two years. It needed a lot of aging because of the honey. I’m trying to devise a paleo beer with honey, sweet potato, and another starch, any thoughts?

This may be a silly question, but I’m allergic to baker’s and brewer’s yeast…does that mean that I should steer clear of kefir, kombucha and other fermented products, or are those products made by the other fermentation process?

thanks so much for this post! I am a paleo mom with 3 little gafers and we’re all paleo – husband, too! i was wondering about yeast – but not having the time right now to really do research about it found this very helpful! especially with planning our christmas deliciousness!!
also, i find myself coming back to your blog over and over for fantastic recipes that actually work and taste ah-freakin-mazing!! so, cheers to you! and thank you again for sharing!

Dear Sarah
I read some of your posts which are very interesting :-) I am diagnosed with celiac disease 3years ago and still not better (mainly tired and duodenitis). That’s why I’m following the autoimmune diet for 3weeks now (I used to be vegetarian for 20years, and diary free for 3years).
Since I started the diet I definitely have more stomach cramps and gas (I suspect SIBO and candidiasis) and since two days I also leave out sweet potatoes, plantains,. I eat quit a lot of coconut flakes and also this gives me gas I think :-((( I try to limit my fruit intake to maximum 2pieces/day (which is hard for me since I love fruit).

6months ago I did also a blood test and tested IgG positive for yeast (and other food).
I was wondering if i should avoid drinking ACV (good for candida) or not? Also I love Kombucha but it makes me so gassy :-(( I already take oregano oil and olive leaf extract for the candida overgrowth.

Thanks a lot!!

You should avoid any foods that give you discomfort or that you have tested positive for a sensitivity/allergy to, so that includes vinegar, kombucha, and other fermented foods. If you have been diagnosed with SIBO, you will need to work with a qualified medical practitioner to treat it. Sarah also recommends a low-FODMAP diet in addition to the AIP: – Christina, Sarah’s assistant

Thanks :-))!! I will avoid all fermented foods in the future…and all disallowed starchy veggies (as I found on your blog somewhere :-)
AIP and no fermented foods (yeast) and no starchy veggies and no coconut and low-FODMAP seem right now too much for me :-(( Before I started the AIP I never had problems with flatulence and tolerated all fruits and veggies well. I did have returning duodenitis (which is gone now), tiredness (which bothers me still and the most) and chronic sinusitis and a swollen lymph node right now :-(

I’m from Belgium and if I google ‘sibo’ I don’t find a medical practioner who is qualified to test this:-((

Many of the physicians on and work from a distance. You may also be able to order testing online (but will need to see a doctor for treatment if the test is positive). Most doctors should be able to perform the testing. It’s either a breath test or a stool test for parasites, bacteria, and yeast. The hard part is convincing them to do it. Sarah recommends low-FODMAP over no-starch for SIBO. You might also consider digestive enzymes to help you digest plants to see if that helps. – Christina, Sarah’s assistant

Thx you so much! I stopped eating plantains, sweet potatoes (that’s why I suspect SIBO),.. because they make me really too gassy. I already take digestive enzymes and a good probiotics and glutamine. I will look for a sibo test online. Are the results from a breath test/stool test reliable? Which of the two tests do you suggest?

The easiest test measures the amount of hydrogen or methane in your breath. The gold standard of testing, though, is to obtain a sample of chyme from your intestine via endoscopy. A stool test can also tell you a little bit about the bacteria in your digestive tract as well as parasites. But none of these are known for being 100% accurate. – Christina, Sarah’s assistant

I had similar symptoms. Take all of your blood tests to a Pharmacist and have him look at what supplements your need. Pretty much every one is low on IODINE because we don’t eat enough fish. If your thyroid is even slightly malfunctioning then your definitely need it. Also he put me on VIT D3 and Selenium supplements. I feel tons better. I had thought just eating a clean AIP diet would help but I was still so tired. The supplements are filling in the tiredness gap.

Thank you for this Sarah. I’ve been wondering about gluten-free beers. The ones I’ve seen are made with barley with the gluten removed. Do you know how they remove the gluten?As they still contain barley, a grain, it would be interested to hear your views on including an occasional gluten free pint in my paleo diet. :-)

Good post. As a pathologist with a PhD in Mycology it always makes me a bit crazy to see people lumping all yeasts together as a yeast free diet. Candida and Saccaromyces are not closely related at all!

So for those of is who are battling Candida overgrowth, you’re saying yeast bread is ok? After recently learning about fermented foods benefits I’ve been toying with the idea of making my own sourdough. I haven’t because I’m torn that it might make things worse again. Now you have me pondering it again. So hard to know what the right thing to do is.

[…] Is Yeast Paleo? » The Paleo Mom – thanks so much for this post! I am a paleo mom with 3 little gafers and we’re all paleo – husband, too! i was wondering about yeast – but not having the time right now to really do research about it found this very helpful! especially with planning our christmas deliciousness!! […]

Is the yeast/mold that grows on food (especially on organic grapes) harmful? I throw away the bad grapes and wash the rest but I’m wondering if that’s enough to get rid of the spores that are not visible and if I should throw away the whole package. Same thing happens to the top of the carrots, since I buy big 5 lb bags for juicing, keep or toss ’em?

I realize that this comment is over a year old, but I didn’t see a reply to it (unless it’s further down the list…). If you are concerned about mold spores on fresh produce, wash it in a solution of apple cider vinegar and water (approximately 1 Tbsp of apple cider vinegar per 1 cup of water). There are several blog posts out there about this. Here are a couple:

This was a question I needed answered right now. Bless you, and thanks for all the info!!!
This journey can be so confusing!

Thank you. You had me with the Info about Yeast & paleo, but this No >> “In fact, a great way to get beneficial yeast and bacteria into your diet is to grow your own vegetables organically and eat them without washing them first. “… too many birds poop, bugs, parasites, cats wandering gardens and let’s not forget the dust & air pollution (high here in AZ) and Chemtrail cloud spraying that settle on gardens & soil with Aluminum, cadmium, barium, lead, mercury and 5 types of mutated toxic molds. ~~ I’ll be washing my garden herbs & veggies. :)

Hi there. Thank you for the information like younI could not find a definitive answer about if yeast is allowed and encouraged. Your information has helped a lot.

Hello. Thank you for all of the advices, that is so great. I have a couple questions. You talk about yeast, but what about nutritional yeast that vegans use everywhere? and what is your take on Chia seeds, is it as good as they say?
Thank you and happy new year to you!!
Christine 😀

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