Milk. It does a body good. Or does it?
Milk has long been purported as one of the best drinks to put into your body. Its calcium makes your teeth and bones stronger, which I remember growing up as many a doctor scolded me for not drinking more, claiming it would lead to osteoporosis as I aged. But recently, there’s been a backlash against milk consumption as consumers are becoming increasingly aware of the additives in store-bought milk (e.g., growth hormones).
Regardless of your personal feelings towards milk, there are many personal anecdotes online about its benefit as a skin exfoliant and toner, with many an internet blogger claiming that rubbing milk on her face left her with brighter, smoother skin. But what exactly is in milk, and how active are its compounds when applied to your skin?
Milk: The Basics
For the purposes of this article, we’re going to focus on cow milk, which can be sold in stores at varying fat contents (whole, 2%, 1%, or skim). Because different fat contents are going to contain different compounds, we’re just going to discuss whole milk, rather than confuse everyone by discussing the different amounts of x, y, and z in different types of milk.
Now that we’ve clarified that, milk contains 87% water, making it an excellent source of hydration. Next, it contains 4.9% carbohydrates in the form of lactose, a type of sugar. Its fat content comes in 3.4%, containing saturated, monounsaturated, and polyunsaturated fats. Finally, proteins make up 3.3%, with vitamins and minerals making up the rest. When you’re buying milk in a store, it has been pasteurized to kill bacteria, homogenized to evenly distribute fats, and fortified to include vitamins A and D (Cornell University).
Lactose and Lactic Acid: What’s the Difference?
While the two may sound quite similar, they’re actually quite different. Lactose is a sugar that makes up 4.9% of milk. Your body produces an enzyme called lactase which breaks down lactose when you digest dairy products. If you’re not producing enough lactase, your body can’t break down the lactose quickly, making you lactose intolerant and an avoider of the important things in life (e.g., cheese) (Livestrong).
Lactic acid, on the other hand, is an alpha hydroxy acid that exfoliates dead skin cells and moisturizes the skin. While glycolic acid is more firming because it penetrates your skin deeper, lactic acid is better for those with more sensitive skin as its larger structure keeps it from penetrating too deep. Of course, it still smooths the skin and is incredibly moisturizing, which is why it’s included in one of the only FDA-approved drugs to improve skin hydration, LacHydrin (JAAD).
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One of the most commonly-cited reasons for using milk as a toner is the supposed inclusion of lactic acid, which would exfoliate and smooth your skin. While the latter is true, the former is not. You see, store-bought milk doesn’t contain much lactic acid, or at least it shouldn’t. Fresh milk contains an whopping 0.003% lactic acid (Journal of the Science of Food and Agriculture), which might sound extremely low, but it’s not a bad thing. Bacteria found in milk will break down the sugars (lactose), producing lactic acid which will make your milk thicker and sour. So the more lactic acid present, the more bacteria. So when you open your half-full gallon of milk a full two weeks after its sell-by date, you’re smelling the sour, rancid smell of the by-products of bacteria on a lactose binge, also known as lactic acid (The Journal of Biological Chemistry). Unless you’re planning on applying expired milk to your skin, I wouldn’t count on the lactic acid in store-bought milk doing much for your skin.
But What About the Other Stuff in Milk?
Look, just because milk doesn’t really contain lactic acid, doesn’t mean it’s not somewhat good for your skin. Its 3.4% fat content, for instance, includes fatty acids like linoleic and linolenic acids. Linoleic acid is an emollient, which means it moisturizes and softens the skin by filling in the spaces between your cells (Hardvard Health Publications). And linolenic acid is necessary for the production of ceramides, which strengthen the skin barrier and help it retain water (Dr. Leslie Baumann, M.D.). The two fatty acids can also protect against UVB-induced erythema (redness) in hairless mice when applied topically (Photochemistry and Photobiology).
As far as vitamins are concerned, milk has plenty. Vitamin A, also known as retinol, prevents collagen loss and increases cellular turnover (Cosmetic Dermatology); panthenol, or vitamin B5, is a humectant moisturizer that also aids in wound healing by increasing fibroblast production (International Journal of Cosmetic Science, Drug & Cosmetic Industry); and vitamin D treats inflammation by suppressing lgE production and lgE modulated immunological reactions (Experimental Dermatology). While this all sounds great for your skin in theory, keep in mind that your skin can’t really absorb these vitamins the same way they do for vitamin derivatives in cosmetics that have been formulated to better penetrate your skin (Discovery Health). And let me again mention the 2007 study that concluded that ingesting ingredients is way more beneficial for your skin than topically applying them (Skin Pharmacology and Physiology).
Verdict: TRICK
As much as I’d like to give props to Cleopatra, the most famous ancient spokeswoman for the milk bath, I just can’t bring myself to do it. It has potential, really; due to its fatty acid content, it has great moisturizing properties, which is what I’m sure gives users a glow after trying the facial. But the lactic acid isn’t present at high-enough concentrations to make a different in your skin texture and tone, so using it for that purpose seems silly. Plus, the vitamins present in milk aren’t necessarily going to do anything since they’re not easily absorbed. So what are you to do?
Well, if you’re looking for an even tone, try our FutureDerm Vitamin CE Caffeic Silk Serum, which uses 16% vitamin C and 2% vitamin E to give your skin a healthy glow. And if you’re really into the whole lactic-acid-in-dairy-products thing, try the Korres Greek Yoghurt Advanced Nourishing Sleeping Facial ($34.95, amazon.com), which will moisturize your skin as you sleep.