Get Cultured! Fermented vs Pickled
- ketogenicfasting
- Apr 23
- 10 min read
Updated: 2 hours ago
Many low-carb dieters avoid fermented foods, fearing they are too high in carbohydrates. This is a misconception — properly fermented foods are generally low in carbs and rich in beneficial probiotics.
The true foods to avoid on a low-carb diet include:
Sugars: white sugar, brown sugar, honey, maple syrup, and other natural sweeteners
High-sugar fruits
Starches: all grains, most legumes, starchy vegetables (e.g., potatoes, beets)
Fermentation is an ancient food preservation method that predates refrigeration.
With the advent of modern refrigeration and industrialized food production, traditional fermented foods became less common. This shift away from fermented, probiotic-rich foods may be a contributing factor to the rise in chronic health issues.
Including fermented foods in a low-carb diet can support gut health and overall wellness without compromising carb limits.
Fermented foods are experiencing a strong resurgence—and for good reason.
People are rediscovering that fermentation enhances the nutritional value of foods by cultivating beneficial bacteria.
These healthy bacteria help colonize the gut, supporting digestion, immunity, and overall wellness.
It’s now widely recognized that consuming even a tablespoon of fermented food with each meal can significantly contribute to optimal health and nutrition.
Benefits Of Fermented Foods
The fermentation process produces Lactobacillus, a beneficial probiotic that colonizes the gut and supports the natural balance of intestinal flora. This, in turn, enhances digestion, boosts immune function, and improves nutrient absorption.
Lactobacillus is a species of "friendly" bacteria (probiotic) that naturally lives in the digestive, urinary, and genital systems without causing disease.
It helps restore healthy intestinal flora, particularly after antibiotic use.
Lactobacillus is also used to help prevent antibiotic-associated diarrhea and reduce the risk of post-antibiotic vulvovaginal yeast infections (candidiasis).
For more info on Lactobacillus, please read this article by Ana Aleksic, MSc (Pharmacy).
In the 1960s, Lactobacillus reuteri was present in the microbiomes of approximately 40% of the population. Today, it is estimated to be found in only about 10% of people. This significant decline is largely due to the modern diet’s lack of traditionally fermented foods.
Consuming a wide spectrum of beneficial bacteria from fermented foods has been linked to numerous health benefits, including:
Improved weight management
Lower blood sugar levels
An added benefit of cultured dairy is that the live bacteria used in fermentation help break down lactose—making it easier to digest, especially for those who are lactose intolerant.
According to Dr. Joseph Mercola, regularly consuming probiotic-rich fermented foods offers a variety of health benefits, including:
Essential nutrients:
Some fermented foods are excellent sources of key nutrients, such as vitamin K2, which helps prevent arterial plaque buildup and supports heart health
Immune system support:
An estimated 80% of your immune system resides in your gut. Probiotics aid in the development of the gut’s protective mucus lining, which plays a critical role in immune defense.
Powerful detoxification:
Beneficial bacteria in fermented foods act as potent natural detoxifiers, helping your body eliminate toxins more effectively.
Diverse microflora:
Eating a variety of fermented foods provides a broader spectrum of beneficial gut bacteria than most probiotic supplements can offer.
Fermentation Lowers the Carb Count of Foods
The fermentation process naturally reduces the carbohydrate content of foods.
This happens because beneficial bacteria feed on the sugars and starches present in the food.
As they consume these carbs, they convert them into lactic acid, carbon dioxide, and additional probiotic bacteria.
The result is a food that is lower in sugar, easier to digest, and richer in gut-friendly microbes.
During fermentation, bacteria and yeast consume carbohydrates in the food as their energy source.
In kombucha, the bacteria feed on sugar.
In sourdough bread, they consume the carbohydrates in flour.
In sauerkraut, they digest the natural sugars in cabbage.
In yogurt, the bacteria break down lactose, the milk sugar.
By definition, fermentation is a process that reduces the carbohydrate content of food as the microbes convert sugars and starches into beneficial byproducts like lactic acid, carbon dioxide, and probiotics.
"The longer the fermentation process, the more carbohydrates are consumed by the organisms, resulting in a more sour flavor and a lower dietary carbohydrate content.
Low-carb Fermented Foods
Fermentation boosts the natural nutrient value of foods!
Kombucha
Allow your kombucha to ferment until it develops a pleasantly bright, balanced tang—this is a sign that the sugars have been properly metabolized and the brew has matured. For those seeking a drier, more refined profile, a second fermentation (bottled and sealed, optionally with natural flavorings like citrus peel or ginger) will further reduce residual sugars while deepening complexity, natural carbonation, and aroma.
If you’re starting from a quality store-bought artisan kombucha, you can use it as a foundation to grow your own culture. Choose a raw, unpasteurized bottle with visible live cultures. Pour it into a jar with freshly brewed, sweetened tea (typically black or green tea with organic sugar), cover with a breathable cloth, and allow it to sit undisturbed at room temperature.
Over time, a new SCOBY—the “mother”—will begin to form on the surface. Once established, this living culture can be reused batch after batch, allowing you to craft your own kombucha with consistency and control over flavor, sweetness, and fermentation level.
Yogurt
For yogurt making, you can either reuse live cultures from a high-quality artisan yogurt or work with dedicated starter cultures for greater consistency. Simply reserve a few spoonfuls of yogurt with active cultures and introduce it into warm milk to begin fermentation—this method has been used traditionally for generations.
Alternatively, commercial starter cultures offer more predictable results and specific strains, but they must be kept refrigerated to maintain their viability. Both approaches allow you to cultivate your own yogurt at home, with control over texture, tang, and fermentation time.
To ensure that almost all of the lactose is used in culturing, the best practice is to allow yogurt to ferment for a full 24 hours (thermophilic cultures) or 48 hours (mesophilic cultures). To maintain the culture's viability, some of the yogurt should be removed and refrigerated after the standard culturing time.
Hard Cheese: A Naturally Low-Carb Fermented Food
Although some dairy products like milk and yogurt are relatively high in carbohydrates, the fermentation process used to produce cheese significantly reduces its carb content. Beneficial bacteria consume lactose (milk sugar), and as cheese continues to age, even more of that lactose is broken down. At the same time, moisture is gradually lost and flavors become more concentrated, transforming the texture from soft and pliable to firm, granular, or crumbly. This is why hard, aged cheeses like cheddar or Parmesan contain very little to virtually no carbohydrates, whereas fresh, softer cheeses like ricotta or cottage cheese retain more of their natural milk sugars.
As a general rule, the longer a cheese is aged, the lower its carbohydrate content and the more concentrated its protein becomes. Low-moisture, aged cheeses are therefore ideal for a low-carb, high-protein lifestyle. For example, Parmesan contains around 10 grams of protein per ounce, while most cheeses provide 6–7 grams per ounce. In contrast, fresh cheeses such as cottage cheese, ricotta, and cheese spreads typically contain less than 3 grams of protein per ounce and retain slightly more carbohydrates.
For those seeking very low carbohydrate options, traditionally aged cheeses are the clear standouts. Varieties such as Parmigiano-Reggiano, Pecorino Romano, aged cheddar, and Grana Padano contain virtually no carbohydrates, while cheeses like aged Gouda, Comté, Gruyère, Emmental, and Jarlsberg contain only trace amounts. Even softer cheeses like Brie and goat cheese (~0.3g carbs per ounce) and blue cheese or cheddar (~0.4g per ounce) remain relatively low in carbs, though not as minimal as long-aged varieties. Parmesan, for example, contains about 0.9g of carbohydrates per ounce, still fitting well within a low-carb framework.
In contrast, higher-moisture cheeses such as cream cheese, cottage cheese, ricotta, and processed cheese spreads—while still moderate—tend to contain around 1 gram of carbohydrates per ounce and are less desirable for strict low-carb or ketogenic diets. Ultimately, the harder and more aged the cheese, the lower its carbohydrate content, making these cheeses not only metabolically favorable but also rich in flavor, complexity, and digestibility.
As a general rule, the harder and more aged the cheese, the lower its carbohydrate content—making these cheeses ideal for a strict keto or low-carb lifestyle while also offering exceptional depth, complexity, and digestibility.
Fermented Vegetables
Any fermented vegetable—including naturally sweeter ones like beets and carrots—can be considered relatively low in carbohydrates when prepared properly. During fermentation, beneficial bacteria consume a portion of the vegetable’s natural sugars, converting them into lactic acid. This not only preserves the vegetables but also reduces their effective sugar content while creating that characteristic tang and depth of flavor.
As a result, foods like sauerkraut, traditionally fermented pickles (not vinegar-brined), and fresh fermented salsas become more metabolically favorable than their raw counterparts. The fermentation process also enhances nutrient availability, supports gut health through beneficial microbes, and improves digestibility.
Even with root vegetables like carrots and beets—which start out higher in natural sugars—the fermentation process helps offset some of that carbohydrate load. While they may not reach the near-zero levels of aged cheeses, they can still fit comfortably into a low-carb or ketogenic lifestyle when consumed in moderation. The key is to focus on true fermentation (salt-brined, live-cultured) rather than products preserved with vinegar, which do not offer the same metabolic and probiotic benefits.
How to Ferment Vegetables at Home
Choose fresh vegetables
Use clean, fresh vegetables such as cabbage, cucumbers, carrots, beets, cauliflower, peppers, or onions.
Cut the vegetables
Slice, shred, chop, or leave them whole, depending on the recipe and desired texture.
Prepare a salt brine
Use about 2% salt by weight, or roughly 1–2 teaspoons of salt per cup of water.
Pack into a clean glass jar
Place the vegetables into a clean jar, leaving some space at the top.
Add herbs and spices
Optional additions include garlic, dill, mustard seeds, peppercorns, bay leaves, rosemary, or chili flakes.
Submerge completely
Pour the brine over the vegetables until fully covered. Keep everything below the liquid to prevent mold.
Cover loosely
Use a fermentation lid, airlock, or breathable cover so gases can escape.
Ferment at room temperature
Let the jar sit for several days to two weeks, depending on how tangy you want the vegetables.
Taste and monitor
Check flavor as fermentation progresses. The vegetables should become pleasantly sour and aromatic.
Refrigerate when ready
Once the flavor is right, move the jar to the refrigerator to slow fermentation and preserve freshness.
Kimchi
Kimchi is a traditional Korean side dish of salted and fermented vegetables, such as napa cabbage and Korean radish. A wide selection of seasonings are used, including gochugaru (Korean chili powder), spring onions, garlic, ginger, and jeotgal (salted seafood), etc. Kimchi is also used in a variety of soups and stews.
Chimichurri
Chimichurri is an uncooked sauce from Argentina and Uruguay that is used as a condiment and absolutely stellar on grilled meats.
Traditionally it is made with fermented parsley along cilantro and basil.
Chimichurri is brushed, basted, spooned onto meat as it cooks, served as a condiment, or used as a meat marinade.
How to Ferment Chimichurri
Prepare the herbs
Finely chop fresh parsley, garlic, and a small amount of chili or red pepper flakes.
Add salt
Mix in about 1–1.5% salt by weight to help draw out moisture and support fermentation.
Avoid vinegar at first
Do not add vinegar before fermentation. True fermentation develops natural acidity through beneficial bacteria.
Pack into a clean glass jar
Press the herb mixture firmly into the jar so the natural juices begin to rise.
Keep the herbs submerged
Add a small splash of filtered water if needed to keep the herbs mostly under the liquid.
Cover loosely
Use a fermentation lid, airlock, or loose lid so gases can escape.
Ferment at room temperature
Let it sit for 1–3 days, depending on how tangy you want the flavor.
Add olive oil after fermentation
Once the chimichurri has developed a pleasant tang, stir in high-quality olive oil.
Refrigerate
Transfer to the refrigerator to slow fermentation and preserve freshness.
Use as desired
Enjoy over grilled meats, vegetables, eggs, salads, or keto bowls.
Tempeh
This delicacy originated in Indonesia and is a traditional fermented food made from whole soybeans, bound together in form of a cake through a natural culturing process. Unlike tofu—which is made from soy milk and has a soft, neutral profile—tempeh is firm, dense, and has a nutty, earthy flavor with a slightly tangy edge from fermentation. It is typically sliced, marinated, and pan-fried or added to dishes with bold seasonings to balance its naturally strong taste.
Tempeh is rich in probiotics and also removes anti-nutrients found in soybeans that can prevent the body from absorbing vital nutrients.
While fermentation does offer some digestive benefits, tempeh is not truly keto-friendly for a strict low-carb lifestyle. It still contains moderate carbohydrates compared to animal-based foods and aged cheeses, which undergo more complete carbohydrate reduction. For those focused on metabolic health and very low-carb eating, other cultured foods—such as fermented vegetables and aged dairy—are generally more aligned choices.
Fruit Chutney
While you might want to limit the amount of fruit you eat on a low-carb diet (due to the hidden fructose which does not spike insulin, thus effects are not easily detectable/measurable), fermented fruit chutneys are naturally lower in their natural sugars than their non-fermented counterparts.
Fermented dark chocolate
Cacao beans are fermented prior to making the low acidity chocolate bar. The extra fermentation step reduces the amount of sugars and brings up more pronounced smooth-satin mouth feel and chocolaty notes, delicate spices and flavors. The fermentation also boosts the amount of antioxidants and vitamin B.
Water Kefir & Milk Kefir
Water kefir vs. milk kefir comes down to what they’re fed, how they ferment, and their nutritional profile.
Milk kefir is made by fermenting milk (cow, goat, or sheep) with kefir grains. These grains are a complex culture of bacteria and yeast that feed on lactose, transforming the milk into a tangy, yogurt-like drink. It’s rich, creamy, and naturally contains probiotics, along with protein, calcium, and fats. Because the cultures consume much of the lactose, milk kefir is lower in carbs than milk—but it still contains some, depending on fermentation time.
Water kefir, on the other hand, is made using different grains that ferment sugar water, coconut water, or diluted fruit juice. The result is a light, slightly sweet, effervescent drink—more like a natural soda. While the fermentation reduces sugar, some residual sugars usually remain. It’s dairy-free and refreshing, but nutritionally lighter than milk kefir, with fewer proteins and fats.
In a low-carb or keto context:
Milk kefir is generally the better choice (especially if fermented longer to reduce lactose), while water kefir tends to retain more sugar and is less aligned with strict low-carb goals.
Water Kefir
Allow to ferment longer until good and tart. In order not to stress the grains, remove them after 48 hours, and continue with a second ferment to further reduce sugars.
Milk Kefir
Allow to ferment for the full 24 hours or even longer. A second ferment without the grains will reduce lactose even further.
Fermented vs. Pickled:
Fermented foods contain live bacteria with health benefits, while pickled foods, which are preserved in vinegar, may not offer the same probiotic benefits.
Pickling often destroys live microorganisms, and processed pickles have lost much of their nutritional value.
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