7-Dehydrocholesterol has significant absorption of UV light at the lowest wavelengths of light found in sunlight (290-310 nm). Hence the need for full-spectrum lamps to emit UV-B radiation (UV-B light is defined here to be light between 290-315 NM).
In rare cases some vegans might not get enough fat or calories to produce adequate amounts of steroid hormones (which are produced from cholesterol). Two studies have shown vegans to have sex hormones on par with meat-eaters (1, 2), but one report showed vegan women to have lower levels of estrogen (3).
Dairy Products. A vegan diet excludes milk and dairy products, which are high in calcium, protein and potassium. Vegan substitutes include soy milk, soy or tofu yogurt, and soy cheese. To get adequate calcium, a 2,000-calorie vegan diet should include three servings per day of vegan alternatives to dairy products.