What does your skin, yogurt, and lactic acid have to do with each other?

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July 21, 2023

A friend gifted me some natural-ish bath & body products (face masks, creams, oils, etc). This was a real treat, as I usually make a lot of these things at home (of course, to avoid synthetic additives and greenwashed labels).

One thing that stood out was a “lactic acid treatment” for skin. It boasts exfoliation, removing dead dull surface skin, and restoring clarity and smoothness. It brightens dark spots and discoloration and instantly plumps the look of fine lines and wrinkles. Wow, that sounds great, right?

When I hear the word “lactic acid”, I immediately think about dairy and fermentation. I don’t generally think about skin… but now I am!

I’ve used yogurt and kefir in face masks before, but I was doing it for the probiotics and to balance pH. Since your skin is the largest organ on your body, having a good microbiologic balance is so important. But now, I have another reason – lactic acid!!!

Read on for more info about lactic acid, yogurt, and using it on your skin.

The science behind what lactic acid does for your skin

Lactic acid is an alpha-hydroxy acid (AHA) that is commonly used in skincare products and treatments. It is derived from sources such as sour milk, fruits, and vegetables (more on that later). Lactic acid has several beneficial effects on the skin due to its chemical properties and interactions with the skin's physiology. Here are some key aspects of lactic acid's effects on the skin:

Exfoliation: Lactic acid acts as a chemical exfoliant, meaning it helps to remove dead skin cells from the surface of the skin. It does this by loosening the bonds between skin cells, allowing them to be easily shed. This exfoliating action helps to smooth the skin's texture, improve its tone, and promote a more youthful appearance.
Moisturization: Lactic acid has humectant properties, which means it helps the skin retain moisture. It attracts water molecules from the environment and draws them into the skin, hydrating and plumping it. This moisturizing effect can be particularly beneficial for individuals with dry or dehydrated skin.
Stimulates collagen production: Lactic acid stimulates the production of collagen, a protein that provides structural support to the skin. Collagen helps maintain the skin's elasticity and firmness, and its production tends to decline with age. By promoting collagen synthesis, lactic acid can help improve the skin's elasticity, reduce the appearance of fine lines and wrinkles, and contribute to a more youthful complexion.
Improves skin tone and hyperpigmentation: Lactic acid has the ability to inhibit the production of melanin, the pigment responsible for skin color. By doing so, it can help reduce the appearance of dark spots, uneven skin tone, and hyperpigmentation caused by factors such as sun damage or acne scars. Regular use of lactic acid can lead to a more even, radiant complexion.
Enhances product penetration: Lactic acid also has the ability to enhance the penetration of other skincare products. By exfoliating the outermost layer of the skin, it allows active ingredients in serums, moisturizers, or treatments to penetrate more deeply and effectively, maximizing their benefits.

Natural sources for lactic acid

Lactic acid can be found naturally in various food sources. Here are some examples of natural sources of lactic acid:

Fermented dairy products: Lactic acid is commonly present in fermented dairy products like yogurt, kefir, and buttermilk. The bacteria used in the fermentation process convert lactose (milk sugar) into lactic acid, giving these products their characteristic tangy taste.
Fermented vegetables: Lactic acid fermentation is also used to preserve and flavor vegetables. Sauerkraut, kimchi, pickles, and other fermented vegetables contain lactic acid produced by the fermentation process.
Fruits: Certain fruits naturally contain lactic acid. For example, sour cherries, apples, and grapes have lactic acid content, although in relatively small amounts compared to other sources.
Fermented beverages: Some traditional fermented beverages, such as kombucha and certain types of fruit juices, can contain lactic acid produced during the fermentation process.
Sourdough bread: Sourdough bread is made by fermenting a mixture of flour and water using wild yeasts and bacteria. Lactic acid is one of the byproducts of this fermentation process, contributing to the unique flavor and texture of sourdough bread.
Some types of meat and fish: Lactic acid can also be produced during the fermentation of certain types of meat and fish. Examples include traditional cured and fermented meats like sausages or fish sauces like Thai fish sauce.

Should I put any kind of food containing lactic acid on my skin?

Well, of course the only person who can answer this question is you! At Miller’s Bio Farm, we 100% believe in the right to choose what you consume or put on your body.

That being said, although the natural foods listed above all contain lactic acid, it might not be the best idea to use them directly on your skin. I mean, I’ve never heard of a sourdough mask or kombucha serum or a hot salami treatment. But… I’ve heard of yogurt or kefir being used for skincare, and I’ve done it personally myself with great results.

A grand majority of the internet will likely tell you that store bought skincare products are the only safe source of lactic acid for skin. But, if you’re here reading this, then you likely know that’s absolutely not true.

Sure, skincare products use lactic acid that’s synthetically derived and produced through controlled fermentation processes specifically for cosmetic use. But, on the other hand, they contain synthetic ingredients and unknown additives that you may want to avoid. Plus, making skincare products at home is so much more affordable than buying them pre-made.

The amount of lactic acid in yogurt or kefir vs store bought beauty products

The lactic acid treatment that I was gifted contains 5% lactic acid, and it seems the same is true for similar products. In comparison, yogurt has about 0.9% lactic acid and kefir has about 1%.

So, yogurt and kefir contain a lot less lactic acid than beauty products. What does that mean? To get the results of the store bought counterpart, you need to use it more often.

For us “natural folks”, this is nothing new. For example, if you take an antibiotic, it’s super powered and you need 1-2 pills per day. But, if you opt for a natural antibiotic like garlic or colloidal silver or oregano, you need more doses more often.

Other benefits of using yogurt or kefir on your skin

You’ll get all the benefits of using lactic acid on skin listed above PLUS more:

Moisturization: Yogurt and kefir contain natural fats and proteins that help hydrate and moisturize the skin. They can be particularly beneficial for individuals with dry or dehydrated skin, providing a boost of moisture and helping to improve skin elasticity.
Exfoliation: The lactic acid helps with exfoliation, but the natural enzymes in yogurt and kefir also gently exfoliate the skin. They help to remove dead skin cells and promote a smoother complexion, improving the skin's texture and brightness.
Acne treatment: Yogurt and kefir have antimicrobial properties that can help inhibit the growth of acne-causing bacteria. Applying yogurt or kefir topically may assist in reducing acne breakouts and calming existing blemishes.
Supporting the skin's natural barrier: Probiotics can enhance the skin's natural protective barrier by reinforcing the skin's defense mechanisms. This can help strengthen the skin's ability to retain moisture, protect against environmental aggressors, and prevent the penetration of harmful microorganisms.
Calming skin inflammation: Probiotics have anti-inflammatory properties that can help soothe and calm irritated or inflamed skin. By reducing inflammation, they can assist in managing conditions such as acne, rosacea, or eczema.
Balancing the skin's pH: The acidic pH of yogurt and kefir helps maintain the skin's natural pH balance, which is important for a healthy skin barrier function. By preserving the optimal pH level, probiotics in yogurt and kefir can promote overall skin health and prevent the overgrowth of harmful bacteria.
Regulating sebum production: Some studies suggest that certain strains of probiotics can help regulate sebum production in the skin. Excessive sebum production can contribute to oily skin and acne, so balancing sebum levels may lead to improved skin clarity.

Recipes for homemade yogurt or kefir masks

If you’re looking to avoid chemical-laden beauty products or simply save money by making body products at home, here are a few simple yet amazing recipes. For each recipe, simply mix the ingredients together and apply to clean, dry skin. Let sit for 15-20 minutes before rinsing with lukewarm water.

Antibacterial Yogurt & Honey Mask

Add the antibacterial and hydrating benefits of honey.

2 tablespoons plain yogurt (or kefir)
1 tablespoon raw honey

Anti-Inflammatory Yogurt & Turmeric Mask

Add the anti-inflammatory and antibacterial benefits of turmeric.

2 tablespoons plain yogurt (or kefir)
1 tablespoon turmeric

Purifying Yogurt & Activated Charcoal Mask

Add the cleansing and purifying properties of activated charcoal.

1 tablespoon plain yogurt (or kefir)
1 capsule of activated charcoal

Exfoliating Yogurt, Honey & Oats Mask

Add the exfoliating benefits of ground oats and the antibacterial and hydrating benefits of honey.

2 tablespoons plain yogurt (or kefir)
1 tablespoon raw honey
1 tablespoon finely ground oats (or almonds)

If you’d like, you can add 1-2 drops of essential oil to the above recipes for fragrance and added benefits:

Lavender Essential Oil: Soothes and calms the skin, promotes relaxation, and has antibacterial properties.
Tea Tree Essential Oil: Known for its antibacterial and antifungal properties, helps fight acne and blemishes, and can aid in controlling excess oil.
Frankincense Essential Oil: Helps promote skin regeneration, reduce the appearance of wrinkles and fine lines, and has a rejuvenating effect on the skin.
Rosehip Essential Oil: Rich in vitamins and antioxidants, helps reduce scars, hyperpigmentation, and signs of aging, and provides deep hydration to the skin.
Chamomile Essential Oil: Known for its calming and anti-inflammatory properties, soothes sensitive and irritated skin, and can help with conditions like eczema and rosacea.
Geranium Essential Oil: Balances sebum production, tightens the skin, and promotes a healthy complexion. It is also known for its uplifting aroma.
Ylang Ylang Essential Oil: Helps balance oil production, improves skin elasticity, and has a calming and uplifting effect on the mind.
Neroli Essential Oil: Regenerates and rejuvenates the skin, reduces the appearance of scars and stretch marks, and has a beautiful floral fragrance.
Carrot Seed Essential Oil: Rich in antioxidants and vitamins, promotes skin rejuvenation, helps improve skin tone, and provides natural sun protection.
Patchouli Essential Oil: Known for its cell-renewing properties, helps with skin conditions like acne and eczema, and has a grounding and earthy aroma.

*It's important to note that while lactic acid offers several benefits for the skin, it can also cause sensitivity, especially in higher concentrations or for individuals with sensitive skin. It is recommended to perform a patch test before using lactic acid products and to start with lower concentrations, gradually increasing if tolerated well. Consulting with a dermatologist or skincare professional is always advisable to determine the best approach for your specific skin needs.

Our bone broth tested A+++ for heavy metals 🥳 NATURAL AND CLEAN

*Originally published on 3/14/25. Updated on 4/15/25. Over the past few months a bunch of people asked us if we tested our bone broth for toxic heavy metals. When we get the same question a lot, we of course look into it. My first question was --- Is there an issue with toxic metals in bone broth? As it turns out, yes, there "can" be an issue! Heavy metals are naturally present in our environment. We need the "good" heavy metals to thrive: iron, zinc, magnesium, copper, etc. But, we can 100% do without the toxic heavy metals: arsenic, cadmium, lead, mercury, etc. Too many toxic heavy metals can lead to a host of pretty awful issues: nervous system damage, cardiovascular issues, cancer, endocrine disruption, kidney damage, and so on. Our body is designed to excrete heavy metals through urine (and a little bit through sweat, hair, and breastmilk too)... but only so much. There's a limit. If you're overloaded, your body will store those heavy metals in your bones, blood, tissues, and organs. Similarly, if an animal is exposed to heavy metals via food, water, air, dust, or soil, those heavy metals accumulate in the body. Depending on the metal, it can accumulate in the bones, muscle, skin, brain, etc. Maybe the farm's soil or air is contaminated from a nearby factory. Maybe the pipes for the water has lead solder connecting them. Maybe the feed a farm is buying was grown on contaminated soil or processed on contaminated equipment. And, of course, a main purpose of bone broth is drawing out as much as possible from the bones. If there are heavy metals in bones, they will make their way into the broth. This is especially true when you use apple cider vinegar to draw everything out and make it thick and gelatinous and nutrient rich (like our broth). And that led me to my second question --- Should I be concerned about every bone broth? Where is the fear coming from? Well... it seems it might be a little political. There was a study done in the UK in 2013 that scared a lot of people. It's titled "The Risk of Lead Contamination in Bone Broth Diets". This study found high levels of lead in organic chicken bone broth, which is quite concerning. And, in fact, this one study is still cited in articles written today! Let's dig a little deeper. Let's go farther than the short abstract. Here are the broths tested in the study and their test results for lead: (9.5 parts per billion): Broth made from tap water plus skin and cartilage(7.01 parts per billion): Broth made from tap water plus bones(2.3 parts per billion): Broth made from tap water plus meat(0.89 parts per billion): Tap water alone cooked for the same amount of time as a control. But, they only used organic chicken from one farm. And, there's zero information about that farm, their practices, the feed, and the broth recipe. Did they use vinegar or wine in the broth? Was the chicken's water contaminated with lead? What was the quality of the feed and the soil? Were the chickens raised indoors or outdoors? So many unanswered questions! All we get is that it was one "organic chicken" that created a lead issue with broth. Another curious thing is that the broth with skin and cartilage contained more lead than the broth made with just bones. Bones are where lead is stored, so why wouldn't the broth made with bones only contain more lead? It's an odd result. Moreover, the abstract of the study specifically called out "bone broth diets" like GAPS and paleo. They even go so far as to write, "In view of the dangers of lead consumption to the human body, we recommend that doctors and nutritionists take the risk of lead contamination into consideration when advising patients about bone broth diets." That's quite curious. Why are they worried about these diets? Are the researchers anti healing through food? Who funded the research? Is it political? My opinion? This study is not comprehensive. It does not speak to all bone broths. But it does cover a potential issue if the water or animals are overloaded with heavy metals. And, as we know, our poor planet is becoming more and more contaminated with toxins like these toxic heavy metals 😢 What I glean from this study is that we need more research. We need to stay vigilant and test from time to time. We don't need fear to spread and people to stop drinking broth from this one study. Regardless of whether the fear was fabricated or legit, we tested our bone broth anyway. After all, it's always nice to validate that your food choices are as clean as you think. For Miller's, here were my concerns before testing: What if there's mercury in the fishmeal in our chicken feed?What if the soil that our animals live on is contaminated?What is the well water that the broth is made with is contaminated?What if the Celtic sea salt has lots of heavy metals? We actually tested twice. As it turns out, the first test results from March had a LOQ (limit of quantification) that was to high. So, we sent new products in April for testing at a lower LOQ. The results are in! Our bone broth tested A+++ for arsenic, cadmium, lead, and mercury. You can find the actual Eurofins test results right here! For easy reference, here's a chart summarizing the results: You'll notice that, for every sample, the results are "<2.0 μg/kg" and "<4.0 μg/kg". The "<" indicates the limit of quantification (LOQ), the lowest concentration that can be accurately tested using the test procedure in that sample type. So if a "<" result appears, it means that none of that metal was found in the sample above the specific reporting LOQ. Whether or not they were present below this LOQ is information that's not provided by the test. It's also important to note that a μg/kg is a part per billion (ppb). So, for 1 μg/kg, in every billion grams of that food, there would be one gram (or 0.0000001%) of that particular heavy metal. The small numbers matter when it comes to toxic heavy metals, since it doesn't take all that much for your body to become inundated and start experiencing issues or damage. These results are excellent. It means the broth definitely isn't overloaded with toxic heavy metals and are within safe levels. Our amazing customers mentioned Mike Adams to me numerous times after we released the first set of broth results. Mike Adams is an outspoken consumer health advocate, investigative journalist, activist, and science lab director. It turns out Eurofins, the lab we used, is a lab that he recommends. Moreover, our results land us in his highest rating when it comes to heavy metals! I think we're doing pretty great when it comes to providing clean, natural food. But, one result did make me pause. You might be thinking what I first thought -- "But wait, you got a reading above 4.0 μg/kg for arsenic. Isn't that bad?" Let's dive in -- What's up with arsenic? First off, it's important to note that there are organic forms of arsenic as well as inorganic forms. Our body can handle the organic kind pretty well. But, the inorganic kind is carcinogenic. Our test results show the level of all arsenic, and it doesn't divide inorganic and organic. Second, as you can see from the Health Ranger rating above, your body can tolerate way more arsenic than the other three toxic heavy metals. It can handle 6x more than cadmium, 25x more than lead, and 103x more than mercury. Third, it was a mystery to me how arsenic had a reading in the ground beef but not the beef bone broth. Thankfully, that has a pretty easy explanation. Whereas lead mainly accumulates in the bones, arsenic accumulates more in the organs and muscles. And, of course, meat is muscle. And finally, it was also quite perplexing how arsenic showed in our beef as well as our chicken. You see, our beef and chicken are grown on two separate farms (hours apart) and are processed at two separate processors (also hours apart). They're fed two completely separate diets, too! My only explanation is farmland in general or maybe even our environment in general. Organic arsenic has always been naturally present in the soil and water. It's just there in small amounts. But, levels nowadays are likely higher due to overuse of products laden with inorganic arsenic over time. Starting in the 1940s, conventional farmers would include drugs filled with inorganic arsenic in the feed for pigs and chickens and turkeys to encourage fast growth and prevent disease. Ugh. This actually led to concerns about arsenic poisoning, and that that practice was banned recently, in 2016. It makes me think that all the agri-waste has contaminated our farmland a bit, perhaps in both the soil and water. And then of course there are synthetic pesticides and herbicides and fertilizers that may contain inorganic arsenic. And their use on conventional farms might runoff everywhere else. Since our meats are grown on farms that have been naturally managed for some time, I think that's why our arsenic levels were so low, especially compared to conventional meat. Now, let's compare our results to food in general. Ours are extremely low. The data below is based on a few scientific studies: Arsenic: Rice contains anywhere from 90-450 ppb (that includes that rice cereal for babies, too). Meat and poultry in general typically contain 100-200 ppb. The max ours has is 6.8 ppb.Cadmium: Spinach contains 117-222 ppb. Rice contains 6-19 ppb. Meat and poultry in general contain about 10 ppb. Our has less than 2 ppb.Lead: Meat and poultry in general contain about 25 ppb. Our has less than 4 ppb.Mercury: The larger the fish, the more time it has to accumulate mercury. Swordfish and king mackerel can have about 1,000 ppb. Meat and poultry in general contain about 10-50 ppb. Ours has less than 2ppb. Wow! Putting that into perspective, it looks like our broth and meat are quite clean and extremely low in toxic heavy metals! Are you satisfied with our heavy metal results? Do you think we should take further action? Should we test other products? Do you worry about toxic metals (or other junk) in your food? Where have your fears stemmed from? I'd love to hear from you. You can comment below (no account required) or contact us 😊 ----- Sources The risk of lead contamination in bone broth dietsBone Broth and Lead Toxicity: Should You Be Concerned?Bone Broth and Lead Contamination: A Very Flawed Study in Medical HypothesesBone Broth, Collagen, and Toxic Metals: A Research ReviewInorganic arsenic toxicosis in a beef herd Consumer Wellness Center Labs Heavy Metal RatingsArsenic in Meat and Animal ProductsInorganic arsenic toxicosis in a beef herdArsenic in brown rice: do the benefits outweigh the risks?A Survey of the Levels of Selected Metals in U.S. Meat, Poultry, and Siluriformes Fish Samples Taken at Slaughter and Retail, 2017–2022Arsenic in your foodDietary exposure to cadmium from six common foods in the United StatesMercury Content in Commercially Available Finfish in the United States Author links open overlay panel

What does your skin, yogurt, and lactic acid have to do with each other?

The science behind what lactic acid does for your skin

Natural sources for lactic acid

Should I put any kind of food containing lactic acid on my skin?

The amount of lactic acid in yogurt or kefir vs store bought beauty products

Other benefits of using yogurt or kefir on your skin

Recipes for homemade yogurt or kefir masks

Antibacterial Yogurt & Honey Mask

Anti-Inflammatory Yogurt & Turmeric Mask

Purifying Yogurt & Activated Charcoal Mask

Exfoliating Yogurt, Honey & Oats Mask

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Our bone broth tested A+++ for heavy metals 🥳 NATURAL AND CLEAN

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