There are several natural sweeteners that can be healthier alternatives to refined sugar. Here are some of the healthiest sweeteners according to the search results:

1. Stevia: This is a very popular low-calorie sweetener extracted from the leaves of a plant called Stevia rebaudiana. It is low in calories, low in fructose, and has no impact on blood sugar levels.

2. Erythritol: This is a sugar alcohol containing about 2.4 calories per gram and may have some benefits for dental and digestive health. Research in rats suggests it may improve bone density and lower the risk of osteoporosis.

3. Xylitol: This is another popular sweetener that is a sugar alcohol. It may have some benefits for dental and digestive health. Research in rats suggests it may improve bone density and lower the risk of osteoporosis.

4. Yacon syrup: This is a unique sweetener harvested from the yacon plant, which grows natively in the Andes in South America. It’s very high in fructooligosaccharides, which function as soluble fibers that feed the good bacteria in your intestine.

5. Monk fruit sweetener: This is a natural sweetener that is extracted from monk fruit. It is low in calories, low in fructose, and has no impact on blood sugar levels.

Other natural sweeteners that can be considered as substitutes for conventional sugar include raw honey, maple syrup, agave, coconut sugar, and date sugar. These sweeteners usually contain more vitamins, minerals, antioxidants, and other bioactive molecules that may be healthful. However, it is important to keep in mind that natural sweeteners are still forms of sugar and are high in calories. Therefore, they should be consumed in moderation.