The Keto Guide to Fermented Food, Part 2

An ongoing series on the place of fermented foods in a ketogenic or low-carb diet.

Article by Mandy Pagano | 13 Dec, 2020

Article originally published on on 1/31/17. It has been lightly edited for re-publication.

Last week, we laid out a basic overview of fermentation and why it, and the bacteria you may get from fermented foods, may be beneficial. This week we'd like to discuss some other health aspects of the fermented foods you may decide to fit into your ketogenic lifestyle. In any discussion on fermented foods, there is a distinction and an individual decision that must be made between purchased products and home-processed consumables.

Commercially Available Foods

During our research, we found that consuming commercially available fermented goods was not recommended by most experts for a variety of reasons, with a few notable exceptions. The fermentation process itself can be highly variable depending on the food with which you start, as well as what's added to the brine, how long the product is allowed to ferment, etc., all yielding an inconsistent end product, which is something food manufacturers loathe. Due to the high desirability of consistency, many foods that were traditionally fermented, like olives, pickles, peppers, and vegetables, are now packaged with acidic brines that yield taste and texture that is similar from jar to jar (which is considered ideal in the food production business) but contain no probiotics.

Even products that are initially fermented are very commonly pasteurized post-fermentation but prior to packaging, killing all beneficial bacteria long before it ever hits store shelves. The general exception to that seems to be yogurt (containers must state "live, active cultures," otherwise it will not contain the beneficial bacteria), although some manufacturers are beginning to carry sauerkraut, kimchi, and Kombucha with active probiotic bacteria (usually found at the grocer's in the refrigerated sections). As always, you need to be hyper-vigilant about reading labels so as to avoid added sugars and other undesirable ingredients.

Other issues that are very pertinent to keto are a result of various labeling laws. In the United States, for instance, manufacturers are required to list nutritional information based on the ingredients with which a product begins. In other words, your packaged food is always labeled as the sum of its parts. For example, in laboratory testing, plain, full fat Greek yogurt with live, active cultures has consistently shown to have between 6 and 8 total carbohydrates per one cup serving. However, labeling laws require the containers to be marked with the carbohydrate content of the milk products with which the yogurt began, and does not take into account the bacterial consumption of lactose that actually yields the finished product. So the nutrition label on your carton of plain yogurt (which may list a carbohydrate per cup well in excess of 10 grams) states the amount of sugar that was in the milk used to make it, and does not take into account the fermentation that turns that milk into yogurt at all.

These labeling issues make it very difficult to determine actual carbohydrate content of fermented foods. As of now, there is no formally accepted process to test for remaining carbohydrates in fermented foods prior to labeling. Therefore, in products we know are generally very consistent- like our yogurt example- we might have a good idea of carbohydrates remaining. Unfortunately, for more varied products, like Kombucha, it can be very difficult to determine the accuracy of the carbohydrate count on the package. One possible solution is to use a refractometer, which can be used to measure sugar content in liquids, however this does not help us with solid foods. 

The good news is that when it comes to yogurt, things look to be trending the right way, and we are beginning to see more labels that reflect a carb count closer to what we should expect if those lab results are correct. Many other products, though, haven't caught up to that kind of specialized labeling, and so it can be hard to discern whether or not the carbs you see on the label are from before or after fermentation, all of which makes a substantial difference in whether or not we, as ketonians, should consume it.

The one true benefit to consuming commercially prepared fermented goods is that the likelihood of contamination by dangerous bacteria is very, very minute (no more than any other type of food product). The advantages of the consistent environment, as well as near identical processing and packaging procedures generally insures that the end product is highly unlikely to contain anything that's going to make you sick.

Home Fermented Goods

It is widely agreed amongst the experts that the best way to consume fermented foods for probiotic benefits is to process them yourself at home. In this way, you can control ingredients, fermenting conditions and times, and will know that the cultures you're consuming are indeed alive. When considering fermented foods in the context of a ketogenic lifestyle, this is ideal because it means you have total control of what goes into your probiotic boosting foods and how long it is allowed to ferment. It is entirely possible that home fermented vegetables, for instance, that begin with little or no added sugars will produce an end product with a minute sugar content if left to ferment long enough.

However, the disadvantage to making your own is that there is more risk for incorrect processing due to the varying conditions in the home and less precise tools for processing and monitoring, and thus greater potential for contamination by extremely harmful bacteria like listeria or c. Botulinum. Failure to adequately wash the food, your own hands, and to properly sterilize containers may allow for toxic bacteria to grow. Salt content and ambient temperatures must also be within certain ranges to inhibit the development of harmful organisms in your home brews.

If you are considering fermenting your own foods at home, it is incredibly important to follow good food safety procedures, use very precise and high quality tools, and to understand the processes involved (you can begin learning about proper processing for vegetables here and here).

Stay tuned for part 3.

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