Kefir is a fermented drink with many beneficial properties: let’s see in detail what it is and what it is good for.
Kefir draws its origins from the territories of the Caucasus, in decidedly remote times. Known almost everywhere thanks to the cultural mixes and the massive use of the net, kefir has also reached Italy, where it is now appreciated among the proponents of well-being and healthy nutrition.
In the following paragraphs, the many aspects of kefir, its nutritional values and its beneficial properties for human health will be described. Some details will follow on the different versions of kefir and their culinary applications, as well as on the quantities of consumption and any related contraindications. Some practical and commercial indications will close the article.
What is Kefir
Kefir is a fermented product which is obtained by incubating “kefir grains” with milk, vegetable drinks or sugared water. The kefir grains constitute protein and polysaccharide matrices, in which a complex mixture of bacteria and yeasts resides. These microorganisms live with each other in symbiotic association and are composed, among the many species, of lactic bacteria (such as Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus casei, etc.) and various fungal species (such as Saccharomyces cerevisiae).
Kefir is divided into two general types, namely milk kefir and water kefir. As far as its organoleptic characteristics are concerned, milk kefir has a slightly dense consistency, while water kefir is more liquid and opaque. The color of milk kefir can vary depending on the milk used, oscillating between white and yellowish, while that of water kefir changes according to the ingredients chosen, whether they consist of water and sugar only, or even dried fruit and herbs. We will elaborate on the differences in more detail in the following paragraphs.
In general, the taste of kefir is acidic, as is its smell, as well as slightly sparkling and alcoholic. In any case, the organoleptic characteristics of kefir can also vary according to the grains used.
Kefir: calories and nutritional values
Without prejudice to the fact that the nutritional values of kefir may vary depending on the starting drink, 100 g of kefir obtained from low-fat cow’s milk will provide about 43 kcal, for a sugar, protein and lipid content of respectively 4, 61 g, 3.79 g and 1.02 g. The proteins present are of high biological value.
As for the micronutrient content, the contribution of calcium , phosphorus and magnesium, as well as vitamin A and vitamin D are noteworthy. There is also no lack of folates, vitamin B12 and other vitamins of group B. For further details, follow the table relating to the example of kefir proposed.
Nutritional values per 100g of kefir (low fat):
- Waterfall: 89.7 g
- Power: 43 kcal
- Proteins: 3.79 g
- Total fat: 1.02 g
- of which saturated: 0.658 g (total)
- of which monounsaturated: 0.31 g (total)
- of which polyunsaturated: 0.053 g (total)
- Cholesterol: 5 mg
- Simple sugars: 4.61 g
- Fiber: 0 g
- Soccer: 130 mg
- Iron: 0.04 mg
- Magnesium: 12 mg
- Phosphorus: 105 mg
- Potassium: 164 mg
- Sodium: 40 mg
- Zinc: 0.46 mg
- Copper: 0.009 mg
- Manganese: 0.005 mg
- Selenium: 3.6 μg
- C vitamin: 0.2 mg
- Thiamine: 0.03 mg
- Riboflavin: 0.135 mg
- Niacin: 0.15 mg
- Vitamin B5: 0.385 mg
- Vitamin B6: 0.058 mg
- Total folate: 13 μg
- Vitamin B12: 0.29 μg
- Vitamin A: 171 μg
- Retinol: 171 μg
- Vitamin: D (D2 + D3) 1 μg (41 IU)
Kefir: properties and health benefits
Once the general and nutritional characteristics are outlined, it’s time to consider the benefits of kefir. In this regard, a brief description of each property documented or suggested to date on the basis of partial evidence follows
✓ Antimicrobial activity
Several experimental investigations attribute to kefir an interesting antimicrobial power, highlighting the role played, in this sense, by some bioactive components. Produced from bacteria of the genus Lactobacillus, these components are mostly represented by peptides, organic acids and kefiran (an exopolysaccharide), the effects of which have been successfully tested on various microbial strains. The strains in question include the bacterial species Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Escherichia coli and Klebsiella pneumoniae. In relation to kefiran, there is no lack of effects on some fungal species, such as Aspergillus flavu AH3. However, the true extent of the effects described requires careful in vivo evaluations.
✓ Antioxidant activity
Based on some experiments, kefir appears to have antioxidant properties, with significant benefits for human health. In particular, these properties are associated with some biologically active components, such as peptides, phenolic compounds and exopolysaccharides. Overall, these substances appear to act as free radical scavengers , counteracting oxidative stress. As with the antimicrobial activity, the antioxidant properties described for kefir also require further investigation.
✓ Modulating activity on the intestinal microbiota
Preserving the symbiosis existing between the intestinal microbiota and the human body is important for the integrity of the intestinal barrier, for the control of inflammatory processes and for the balance of the immune system . Studies conducted on kefir and its related properties highlight its modulating activity on the intestinal microbiota, although the mechanisms of action must, to date, be fully clarified. Some evidence suggests that specific bioactive components characteristic of kefir (specifically exopolysaccharides) may favor the diversity of the microbiota and increase the presence of “good” bacterial species.
✓ Anti-inflammatory and immunomodulating activity
In vitro and in vivo experiments conducted on pathologies of the intestinal tract have highlighted further properties of kefir. Among other things, it appears that some bioactive components produced by lactobacilli may reduce the expression of some pro-inflammatory mediators (cytokines). The immunomodulating properties of kefir can result in a direct action on the intestinal microbiota or in an indirect action, which is carried out by the bioactive components produced during fermentation. In particular, it appears that these components may promote the cell-mediated immune response against infections.
✓ Antitumor properties
Even in this case, further and more in-depth studies in vivo are necessary, kefir is attributed anti-tumor properties. Specifically, it seems that some components characterizing kefir, such as kefiran and bioactive peptides, can act by inhibiting cell proliferation and activating the mechanisms of programmed cell death (apoptosis). The in vitro evidence available to date mainly concerns cancers of the breast, colon, cervix and liver.
✓ Effects on blood cholesterol levels
The properties of kefir found in vitro also include a positive impact on cholesterol levels , mostly attributed to some bioactive components (exopolysaccharides) produced by lactobacilli. However, this evidence is followed by conflicting results, probably due to the different experimental protocols applied, in addition to the origin of the grains used and the relative fermentation conditions.
✓ Anti-hypertensive property
Although the data in this regard are scarce and the issue therefore remains controversial, kefir is also associated with a beneficial action on hypertension . Specifically, it has been suggested that bioactive peptides produced during fermentation may influence the activity of an enzyme involved in the regulation of blood pressure. Quite intuitively, further studies are needed in this regard.
✓ Antidiabetic property
According to some experimental studies in vivo, the consumption of kefir could be one of the foods useful in the management of type 2 diabetes. In particular, it has been suggested that the bioactive components of kefir may activate molecules involved in the insulin signaling pathway and impact blood glucose and glycated hemoglobin levels.
Water kefir and milk kefir: differences
What are the differences between milk kefir and water kefir? To answer this question, it is good to start with some analogies: in both cases it is a fermented drink and, above all, a probiotic drink capable of bringing benefits to human health. Both therefore contain live microorganisms, although water kefir contains less of them.
In addition to the lactobacilli, already mentioned previously, these microorganisms also include the bacteria of the genera Streptococcus and Leuconostoc, present in both types of kefir. Bifidobacteria are typical of milk kefir, while bacteria of the genus Bacillus are characteristic of water kefir.
In both cases, the bacteria responsible for fermentation live in symbiosis and form the so-called “kefir grains”, which, intuitively, will be different depending on the beverage to be fermented. The grains responsible for the fermentation of milk are called “ kefiran grains ”, while those used in the fermentation of sugared water are known as “ tibicos grains ”. The latter, among other things, are also used for the fermentation of vegetable drinks (such as almond milk, coconut milk, etc.). As can be seen from the recipes proposed below, the realization of the two drinks involves similar steps.
By its nature, water kefir does not contain lactose , while milk kefir will contain a reduced amount of lactose compared to the starting drink. During the fermentation process, the enzyme lactase (beta-galactosidase) is produced, responsible for breaking down lactose into the sugars that compose it. Being low in lactose, even milk kefir can sometimes be taken by lactose intolerant people.
Calories and micronutrient intake will depend on the starting drink (animal milk, vegetable drink, water and sugar) and, in the case of water kefir, on the fruit you decide to add.
How to make kefir at home
Regarding the preparation of kefir at home, it may be useful to describe two different procedures : one for milk kefir and one for water kefir.
- Prepare the milk kefir
A homemade kefir made from common cow’s milk involves the use of 2 tablespoons of kefir grains (or a sachet of freeze-dried enzymes) and 500 ml of fresh pasteurized milk (whole, skimmed or partially skimmed). Then proceed as follows:
- First of all, it is necessary to transfer the grains into a clean and dry glass container, then pour the milk and mix everything with a plastic ladle;
- At this point, it is preferable to cover the container with a paper towel (to be fixed with a rubber band) and put it to rest at room temperature, away from sunlight (the optimal temperature is 25 ° C, so it is not necessary to ‘use of a yoghurt maker);
- After 24 hours, during which it is advisable to mix from time to time, the kefir will have reached the appropriate consistency and the typical hint of slightly sour milk, and can be filtered through a plastic strainer.
The presence of yellowish droplets inside the product indicates the correct level of fermentation. It is preferable to divide the kefir into single portions, in glass containers, and keep it in the refrigerator.
2. Prepare the water kefir
For the preparation of water kefir you need 3 tablespoons of the related kefir grains (or a sachet of freeze-dried enzymes), a liter of water, 3 tablespoons of cane sugar and half a well washed lemon. You can also add dried fruit, such as two dates or a plum. To make water kefir, proceed as follows:
- First of all, you need to pour the water into a glass jug and dissolve the indicated amount of sugar in it;
- At this point, it is possible to add the kefir grains, the lemon in the form of juice and grated peel, and the dried fruit;
- Therefore, it is necessary to cover the container with a sheet of kitchen paper (to be fixed with a rubber band) and leave everything to rest for 24 hours, at room temperature and away from sunlight;
- Finally, the fruit must be removed and everything filtered with a plastic strainer. Water kefir can be stored in the fridge.
How much kefir to drink per day?
Regarding the quantities of consumption, there is no recommendable dose, if not the one that, in general, adapts to subjective nutritional needs. In general, kefir can be included in the diet in the same way as with ordinary yogurt in a jar (125 g). Taking kefir on an empty stomach, as soon as you wake up, is the best way to benefit from its properties.
How kefir is used in cooking
A bit like yogurt, the use of milk kefir lends itself to various recipes, although the most classic method corresponds to white kefir to be consumed as it is. Adding it to fruit, cereals, or chia seeds is another very simple way to consume kefir. Alternatively, milk kefir can be among the ingredients of cakes, donuts and plumcakes, but also among the components of savory recipes, such as scones and salads. The quantities to be used correspond, in principle, to those usually used for yogurt. You can therefore experiment with the use of milk kefir as a substitute for yogurt. A second fermentation (i.e. a grain-free fermentation continued for another 12 hours) will make kefir a valid substitute for yeast.
Kefir and Yogurt: what’s the difference?
For starters, yogurt boasts a denser texture than milk kefir, which, as mentioned earlier, has a more liquid appearance. The flavor also differs between the two products, being sour and slightly sour for kefir, and more delicate and sweet for yogurt.
A rather decisive difference between the two products lies in their composition in microorganisms . Yogurt contains only the two bacterial species Streptococcus thermophilus and Lactobacillus bulgaricus, responsible for lactic fermentation, while kefir is made up of numerous microorganisms, responsible, on the whole, for lactic fermentation and alcoholic fermentation. The latter produces alcohol and carbon dioxide, also impacting the organoleptic characteristics of kefir, which, unlike yogurt, may be slightly alcoholic and sparkling.
Returning to the microbiological composition, it is decisive in differentiating the two products: the microbial species present in kefir, such as lactobacilli, bifidobacteria and yeasts, are able to colonize the human intestine and therefore act as probiotics. This does not happen for the two species characterizing yogurt, which do not survive the intestinal environment.
Does Kefir have any contraindications?
While providing numerous benefits, kefir can sometimes have contraindications. Being a food rich in live microorganisms, kefir may not be suitable for immunocompromised individuals; moreover, the consumption of milk kefir could interfere with any antibiotic therapies based on tetracycline or ciprofloxacin.
While this is not the case for most people, kefir consumption can be associated with gastrointestinal symptoms, such as nausea, stomach pain, constipation, and diarrhea. The consumption of this drink is also contraindicated for those intolerant to histamine or yeast. Finally, milk kefir is not recommended for people with milk casein allergy.
In general and in the presence of some gastrointestinal problems (gastritis, irritable bowel syndrome, etc.) it is preferable to approach the consumption of this food gradually and starting from small doses. In case of doubts, pathologies or pharmacological therapies, it is a good idea to seek medical advice.
As for a spoiled kefir, it is possible to recognize it by the bad smell and excessively viscous grains. In this case it is advisable not to consume the product.
Where to buy kefir: guide to choosing
Once the properties, methods of preparation and uses of kefir have been described, it is time to move on to the purely commercial aspects: where do you buy kefir, then? Wanting to start with a simpler and more immediate option, both milk kefir and water kefir can be purchased at the refrigerated counter of the most well-stocked supermarkets, ready to be consumed or to be used in various recipes.
Should you opt for these products, it is advisable to choose the white versions, with no or low added sugars and no additives. Furthermore, it is preferable to choose products that carry specific information on the label about the lactic ferments contained (although the quantities reported may only partially correspond to the truth). In any case, packaged kefir lends itself to different nutritional needs, consisting, for example, of skimmed milk, delactosed milk, etc.
Where you want to resort to the home preparation of kefir, the “organic” stores, as well as pharmacies, parapharmacies and herbalists, have freeze-dried enzymes in sachets (or the so-called freeze-dried “biostarters”), designed for both types of kefir. Despite being easy to find and simple to use, these preparations contain a smaller variety of lactic ferments than grains. However, these products are also available online, by accessing the most well-known search engines.
Although it is more effective in terms of product properties, the preparation of kefir starting from fresh grains is not an easy way to implement, given the difficult availability of the grains themselves. In this regard, good quality grains are “donated” from person to person, continuing an ancient tradition.