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.
High doses of beta-carotene, especially taken long-term, are not safe. High doses of beta-carotene can turn skin yellow or orange. In people who smoke or who have been exposed to asbestos, beta-carotene supplements might increase the risk of cancer.There is growing concern that taking high doses of antioxidant supplements such as beta-carotene might do more harm than good.eta-carotene is converted to vitamin A, an essential nutrient. It has antioxidant activity, which helps to protect cells from damage. Beta-carotene is safe when used for certain specific medical conditions and taken in appropriate amounts. However, beta-carotene supplements are not recommended for general use.