A Peloton bike and a rose-quartz gua sha have more in common than you might think. They’ve both gotten a lot of play over the last two years, but more notably (in our book), they both make skin look damn good by pumping up circulation, or blood flow, a bodily function that “the skin and every other organ relies on for a supply of nutrients, oxygen, and immune cells,” says Laurel Geraghty, M.D., a dermatologist in Medford, Oregon. When blood flow is restricted, tissue starts to peace out — something anyone who has ever wrapped a Band-Aid around their finger too tightly would understand. When we encourage blood flow (whether by doing a few Down Dogs or lovingly massaging in face oil), we replenish skin with the nutrients it needs to function at its peak. Visible benefits tend to fade quickly, but there may be more happening beneath the surface.
Researchers in Asia — where blood flow has long been viewed as a source of beauty and health — are seeking a new vein of truth. At Kao, a Japanese beauty behemoth that owns Jergens and Curél in the U.S., researchers discovered that better capillary (i.e., baby blood vessels closest to the skin’s surface) blood flow was associated with various markers of skin health, including smoother texture and higher cell turnover. To encourage this through skin care, they took inspiration from older studies that show carbon dioxide application increased circulation via blood vessel dilation. After testing a CO2 solution, researchers found it boosted capillary blood flow in two minutes, and decreased transepidermal water loss to boot, and published the results in the journal Skin Research & Technology. Theoretically, Dr. Geraghty says, it makes sense that “blood vessels would dilate [in the presence of] more carbon dioxide to deliver more oxygen to our tissues.” The research led to a makeover of one of Japan’s best-selling essences, Sofina iP Dodai Essence, to include carbon dioxide in the formula.
But it’s not just blood flow that impacts skin health; scientists at Shiseido think its mode of transportation to the skin is just as important. In the past 20 years, they’ve conducted over a dozen studies as part of a project called Lifeblood, establishing an integral link between skin’s microvascular system — its network of small vessels, including arterioles, capillaries, and venules — and its appearance. Based on previous research, the team decided to study a molecule, called APJ, that can make capillaries thicker and stronger.
Though microscopic, APJ is mighty, acting like a sensor within the capillaries that reads the elasticity of the surroundings, says Shiseido researcher Kentaro Kajiya, Ph.D. He says that “when capillaries become stronger, water, oxygen, and nutrients flow around the capillaries, and the condition of the skin improves.” Shiseido applied this to the revamp of its classic Ultimune serum, infusing it with heartleaf extract, an herb believed to boost APJ expression.
Putting on a well-worn skeptic’s hat, cosmetic chemist Kelly Dobos says that while Shiseido’s studies “show their blend of extracts could promote conditions which could theoretically strengthen capillaries in skin, it would be a challenge for these ingredients to penetrate so deeply that they reach their target in the dermis.” (Shiseido says its studies show its extract increased blood flow in the cheeks. “We have not conducted any tests to increase APJ expression in vivo because the skin needs to be removed; it is a very invasive test. However, we obtained data that the blood flow in the cheeks increased by using the serum,” says Dr. Kajiya, adding that they think this indicates the increased expression of APJ.)