Although milk is a good source for vitamin D sun exposure provides 80 to 90 percent of your daily dose of vitamin D. As per studies which were done by the Harvard Medical School, the most significant and natural input of vitamin D relies on the amount of UVB light that gets through to you. UVB light turns into vitamin D after it reacts with a cholesterol-related compound which in turn creates healthy skin, essential for bone health and even leads improved mental health.
Since sun damage can also lead to skin cancer 10-15 minutes of direct unprotected exposure is recommended. After which using sunblock with 30 SPF or a similar pre-emptive measure is recommended for long-term skin health.