Adding Polyphenol-rich Pulses to Daily Diet Improves Skin Health by Reshaping the Skin Microbiome

Human skin is the largest organ in the body. The slow deterioration of skin appearance and its barrier function are the most prominent signs of human ageing. Cutaneous factors (microbiome and lipids) have immediate and direct impacts on skin health and functions. Intrinsic factors (oxidative stress and inflammation) and extrinsic ones (mostly UV irritation due to sun exposure) affect the skin chronically. Our preliminary research showed that six weeks of cranberry juice intake improved part of women's skin health parameters and decreased oxidative stress. Its activities on the skin correlated with changes in skin microbiome and epidermal lipids. Pulses, especially lentils and beans, are rich sources of polyphenols and fibers. However, there is no clinical evidence on whether adding a serving of cooked mixed pulses with high polyphenol content (lentils, red kidney bean, black beans, and pinto beans) to the diet affects skin health and the underlying causes of skin aging. Women make over 90% of the decisions on food purchases for their families. Skin health is a major concern for women because skin aging becomes visibly noticeable after age 30. The investigators hypothesize that polyphenol-rich pulses improve skin health by reshaping the cutaneous microbiome and lipids and suppressing inflammation and oxidative stress. This hypothesis will be tested in a 12-week clinical trial in 50 women aged 45-65 using a randomized controlled parallel design. The control diet will be formulated using white rice to match the calories and macronutrients of mixed pulses.

Inclusion criteria

• BMI (18.5-29.9)
• Body weight ≥110 pounds
• Fitzpatrick skin type 1,2 and 3.

Exclusion criteria

• pregnancy
• breast-feeding
• impaired fasting glucose
• frequent alcohol use
• history of skin cancer
• sunbathing and the use of tanning bed, intake of vitamin/mineral supplements
• habitual high intake of fruits (≥ 2 cups daily)
• intake of medication that might influence the outcome of the study