**Update: 10/3/19. We are leaving this article up in its entirety, because it has sparked a healthy and somewhat heated debate in the comments. As it turns out, baking soda is actually not harmful to all skin types, and does have a place in the ever expanding world of natural skincare products. We have launched a product that makes use of both baking soda AND oxygenated shea butter. There may be helpful information for you in the article, or in the comments below.**
BAKING SODA is actually a chemical!
This is an important article about some of the science behind baking soda and how it affects the skin. Basically, by altering the skins pH, you are losing a delicate balance of enzymes, healthy bacterial flora, and the integrity of the skins ‘acid mantle’ or protective barrier. Deodorants that contain baking soda are creating a number of negative effects.
Natural Deodorants should not be called Natural if they contain this abrasive, alkalizing chemical called baking soda. The FDA should NOT allow companies to label their products as “natural” if they contain baking soda, a potentially dangerous chemical.
(thanks to Natalie Bell for the amazing info below)
(ZERO natural deodorant does not contain any harmful ingredients and is safe for all skin types)
Why baking soda should NOT be used on the skin!
Stop putting baking soda on your skin. Let me repeat that: Stop putting baking soda on your skin. Baking soda exfoliation is a total favorite of the home remedy set. I’ve seen it in a ton of places, including this article on what Emma Stone uses on her skin, and every time, it makes me cringe a little. Baking soda isn’t just ineffective, it’s actually damaging to your skin. Don’t believe me? Read below and see the science.
Baking Soda + Water is ALKALINE
Let’s start with a little chemistry lesson. Forgive me, chemistry buffs, since this will be information you already know. We’ll start with the Brønsted-Lowry concept, which says that acids are proton donators that are able to give a proton (the hydrogen cation or H+), and bases are proton acceptors that are able to receive a proton (H+).
Bases neutralize acids by bonding with the acid’s hydrogen ion (General, Organic, and Biochemistry).
But, like it or not, the world is not a simple, black-and-white place of acids and bases. Thrown in there are also amphoteric molecules (ions). “Amphoteric” means that a substance has the ability to react with both acids and bases. And some of these amphoteric substances are also amphiprotic, which means they can donate and accept a hydrogen ion. Baking soda’s chemical name is sodium bicarbonate, and bicarbonate is an amphiprotic ion, so it can both take and lose a hydrogen ion. So, this means that baking soda reacts with acids and bases by either donating or accepting a hydrogen ion. But bicarbonate is a stronger base than it is an acid, so it’s more likely to accept a hydrogen.
When you’re making baking soda exfoliator, however, you’re mixing it with water, so the question is what’s the final pH of bicarbonate (HCO3-) and water (H2O). Here’s the chemical formula:
HCO3- + H2O → H2CO3 + OH-
See what happens there? Because it’s a stronger base, it tends to create HO-, rather than H3O+. What this means is that when you dissolve sodium bicarbonate in water, the solution tends to be more alkaline.
See That It’s Alkaline for Yourself
To really prove this, I decided to test it out and mix baking soda with water and test the pH to show you.
When we mixed baking soda and water (more than you’d use for a scrub) and tested it, the pH was about 8.
So Why Is Something Alkaline Bad for Skin?
The pH of the products you use is super important for maintaining healthy skin. Here’s how the pH scale works: It runs from 0-14 with 7 meaning neutral. Anything above 7 is considered alkaline, or a base, and anything below 7 is considered an acid. The skin naturally falls somewhere around 4.5 to 6.5, and is maintained by sebaceous glands, sweat glands, and normal skin flora, among others. This skin acidity is called the “acid mantle” (Exogenus Dermatology).
When you apply a product with a high pH, aka something alkaline, negatively disrupts the skin barrier. A study on skin products found that using an alkaline cleanser, even once, can do damage to the skin (Dermatology). An alkaline cleanser disrupts the skin’s acid mantle (affecting the skin barrier), and changes the bacterial flora composition on the skin and the activity of the enzymes in the upper layers of skin, as these have an optimal pH level. And the damage is cumulative: The longer you use it, the more damage it does to your skin.
So, with baking soda and water, you’re already disrupting the acid mantle, but you’re also manually exfoliating, making it even more damaging and drying.
Because of this, you want mildly acidic products, which help the skin hold moisture and also improve the skin barrier. But it’s important that they’re mildly acidic, as you can, in fact, go too low. If you go too low with products, you risk skin irritation, sun sensitivity, and hyperpigmentation (International Journal of Cosmetic Science). That’s why we don’t recommend that you use straight lemon juice on your skin, for example.