What is Hatoumugi aka Coix Seed?
Hatoumugi goes by many names, most commonly Coix Seed, Job's Tears, Coix lacryma-jobi, and adlay. Originating from Southeast Asia, Coix Seed is an ancient grain that has been cultivated alongside rice in Japan during the early Jomon period (around 14,000 BCE) and is now grown worldwide. It's regarded as a superfood and is often consumed as a tea or food ingredient in not just Japan, but across Taiwan, Korea, China, and Southeast Asia as a regular practice to improve health and complexion.
In Japan, Coix Seed is known by yet another name, Yokuinin, which is the Kampo (Japanese study of traditional herbal medicine) word for the highly concentrated extract of the grain that's sold as oral supplements for skin health. Yokuinin is said to nourish and smooth the skin and to be effective against acne, eczema, and psoriasis.
(Image source: Top 10 Popular Supplements and Japanese Beauty Products at Japan’s Most Famous Pharmacy)
Coix Seed contains 12 kinds of amino acids along with antioxidants and vitamins. Together, these compounds are said to boost the skin's barrier function, help the skin retain moisture and elasticity, even out complexion. (We'll explain the benefits in more detail below). This may be the reason Coix Seed is such a popular skincare ingredient in Japan. In fact, there are brands that revolve singularly around Coix Seed as their star ingredient. Some well-known brands are Naturie's line of Hatoumugi skin conditioning products and Albion.
Benefits of Coix Seed Extract
Repairing Barrier Function
Coix Seed contains 12 different types of amino acids, including Glutamic acid, Aspartic acid, Alanine, Glycine, Histidine, Lysine, Threonine, Valine, Proline, Serine, Leucine, Arginine. Why are amino acids so vital for skin health? Amino acids are the main components of your skin's Natural Moisturizing Factor (NMF), which is the protective coat on your stratum corneum - the outer layer of your skin - that is crucial for maintaining skin hydration and repairing barrier function. As it is rich in amino acids, Coix Seed is able to replenish natural moisturizing factor (NMF) and restore your skin barrier function, helping your skin to better retain moisture, boost elasticity, and protect against external irritants. This could explain why Coix Seed extract is not only popular with people looking to tighten their skin, but also to soothe eczema, psoriasis, and acne and inflammation.
Brightening
Coix Seed contains high levels of Vitamin B3, which has restorative powers. Vitamin B3 helps brighten the skin and even out the complexion by regulating the enzymes involved in melanin production in the skin. By reducing melanin activity, Vitamin B3 can reduce hyperpigmentation and dark spots from forming. Vitamin B3 is especially effective when paired with other ingredients such as Kojic acid, arbutin, and soy - the first two compounds are found in abundance in sake lees and and soy is found in natto. You can actually find all three ingredients in the INÉ Bespoke Skin Nutrient Bars.