The blade on the NutriBullet never requires sharpening, according to the manufacturer, because it is made from durable stainless steel. However, some NutriBullet owners report that the blade dulls over time. Consumers can buy a replacement blade or sharpen the old one using a small, hand-held sharpener.
To sharpen the NutriBullet blade, remove it from the blender base and place it on a flat surface. Examine the blade for dull areas, then run a hand-held sharpening device, such as a diamond-dust sharpening rod or a silicone carbide stone, along its edge. To ensure a straight line, hold the sharpener so that it runs parallel to the blade, instead of at an angle.
Run the sharpener over the blade's edge using firm, even strokes and repeat 10 to 30 times. The website DoItYourself.com offers a tutorial titled "How to Sharpen Blender Blades" that describes a similar process for standard blenders. Do not use an electrically powered sharpening wheel because the stainless steel NutriBullet blade can damage the sharpener at high speeds.
Most customers opt to purchase a NutriBullet replacement blade, either the Extractor Blade or the Milling Blade, which are sold at the official NutriBullet website or by retailers such as Amazon. The Extractor Blade emulsifies food, including tough items, such as fruit skin and seeds, while the Milling Blade grinds ingredients such as grains or fresh herbs.