Stevia rebaudiana, commonly known as stevia or sugar leaf, is a plant species native to South America, utilized for centuries by indigenous peoples, such as the Guaraní, to sweeten local teas and foods. The plant’s popularity as a sugar substitute stems from its leaves containing potent sweet compounds called steviol glycosides. These glycosides, which include stevioside and rebaudioside A, can be 50 to 300 times sweeter than sucrose. This natural sweetness offers a zero-calorie alternative because the compounds are not metabolized by the human body.
Growing Stevia at Home
Stevia is a tender perennial herb that thrives in warm, moist, and sunny conditions, making it best grown as an annual in cooler climates. The plant requires full sun, meaning it should receive at least six to eight hours of direct sunlight each day for optimal growth and sweetness. When planting, stevia prefers loose, loamy, and well-drained soil with a slightly acidic to neutral pH range, ideally between 6.5 and 7.2. Consistent watering is necessary to keep the soil evenly moist, but it must not become waterlogged, as this can lead to root rot.
The plant can be started from seed, though germination can be challenging, so many gardeners prefer to use stem cuttings or purchase starter plants. If starting from seed, it is best to sow them indoors up to ten weeks before the last expected frost. Once the plants reach about eight inches in height, trimming or pinching them back encourages bushier growth, which translates to more harvestable leaves. Stevia leaves are at their sweetest just before the plant begins to flower, so it is beneficial to pinch off any developing flower buds to maintain the leaf quality.
For harvesting, individual leaves can be picked as needed, or entire branches can be cut, but it is recommended to never remove more than one-third of the plant at a time. After harvesting, the leaves can be dried by hanging the branches upside down in a dry, well-ventilated area. Once fully dried, the leaves can be crushed into a powder or stored whole in an airtight container for later use. Bringing potted plants indoors before the first frost allows for continued harvesting during the winter months.
Stevia’s Impact on Health
The primary health advantage of stevia is its zero-calorie profile, which is a direct result of its unique metabolic pathway. The sweet compounds, steviol glycosides, pass through the upper digestive tract without being broken down or absorbed for energy. They are eventually metabolized by bacteria in the colon, where they are converted into steviol, which is then absorbed and excreted without contributing calories. This lack of calorie contribution makes stevia a popular tool for managing weight and reducing overall caloric intake.
The compounds also have a non-glycemic effect, meaning they do not cause a rise in blood glucose or insulin levels. This property makes high-purity stevia extracts a suitable sweetener for individuals managing diabetes or those following a carbohydrate-restricted diet. The U.S. Food and Drug Administration (FDA) has given high-purity steviol glycoside extracts (those containing 95% or more total steviol glycosides) a Generally Recognized as Safe (GRAS) status for use in food. This regulatory status applies only to the highly purified extracts, not to whole-leaf stevia or crude extracts.
The acceptable daily intake (ADI) for steviol glycosides is set at four milligrams per kilogram of body weight per day. This level is considered safe based on extensive scientific evaluation by international bodies like the Joint Expert Committee on Food Additives (JECFA). While generally well-tolerated, some individuals report minor side effects like bloating, nausea, or digestive sensitivity. These effects are typically associated with the sugar alcohols or fillers used in some commercial stevia products, as the safety profile of the purified extracts is well-documented within the established ADI.
Using Stevia as a Sweetener
Stevia is available in several forms, each with a different concentration, including raw dried leaves, liquid extracts, and highly refined white powders. Dried green stevia leaves are 30 to 45 times sweeter than sugar, while purified steviol glycoside extracts can be up to 450 times sweeter. This extreme intensity means a very small amount of refined extract is needed to replace a large quantity of sugar.
When substituting, one cup of sugar may be replaced by approximately one teaspoon of pure stevia powdered extract, or 6 to 9 drops of liquid concentrate. Conversion ratios vary significantly between brands, so follow the specific guidelines provided on the product packaging. The primary challenge when using stevia is its inability to replicate the chemical functions of sugar in baking. Stevia does not caramelize, nor does it provide the necessary bulk, moisture retention, or structure that sugar contributes to baked goods.
To mitigate the characteristic licorice-like or bitter aftertaste, particularly with less refined products, use high-purity extracts like those rich in Rebaudioside A. When baking, combining stevia for sweetness with a bulking agent (such as a sugar alcohol or fiber) can help mimic the texture and volume lost when removing sugar. Liquid concentrates are often preferred for sweetening beverages or no-bake items because they dissolve easily and allow for precise adjustments.