The pH scale indicates acidity or alkalinity. A soil with a pH number below 7 is acid, while one with a pH above 7 is alkaline. Garden plants typically grow best in neutral or slightly acid soil (pH 7 or slightly below; see illustration at left).f your soil is extremely acidic or alkaline and you need to change the level by more than one point on the pH scale, it's best to bring in a professional: he or she can both analyze test results and perform an on-site evaluation to determine whether the soil can be amended successfully and how best to go about it.
There are two different types of vitamin A. The first type, preformed vitamin A, is found in meat, poultry, fish, and dairy products. The second type, provitamin A, is found in fruits, vegetables, and other plant-based products. The most common type of provitamin A in foods and dietary supplements is beta-carotene.
1 Cancer. 2  Beta-carotene does not seem to prevent or decrease death from uterine cancer, cervical cancer, thyroid cancer, bladder cancer, skin cancers (melanoma, basal cell carcinoma, squamous cell carcinoma), brain cancer, and blood cancer (leukemia).eta-carotene is POSSIBLY UNSAFE when taken by mouth in high doses, especially when taken long-term. High doses of beta-carotene can turn skin yellow or orange. There is growing concern that taking high doses of antioxidant supplements such as beta-carotene might do more harm than good.