In this article
Editorial update: September 29, 2026. Text prepared with AI assistance from the sources listed. No independent clinical review. General information, not an individual meal plan.
Short answer
Yes, if it’s sugar-free. The keto food lists summarized by the Harvard Nutrition Source include sugar-free vinegars and mustards among the foods allowed on keto. Prepared yellow mustard has 5.8 g of carbohydrate per 100 g and less than 1 g of sugars, according to the U.S. Department of Agriculture (USDA).
How much carbohydrate does mustard have?
| Food | Total carbohydrate (g) | Fiber (g) | Sugars (g) | Sodium (mg) |
|---|---|---|---|---|
| Prepared yellow mustard (condiment) | 5.8 | 4.0 | 0.9 | 1,100 |
When to be careful with mustard
Mustard with honey or sugar in the recipe is no longer “sugar-free”: check the ingredient list and the carbs per serving. The other figure to check is sodium: 1,100 mg per 100 g in the USDA’s yellow mustard. If you need to limit salt, check this value on the label.
What about mustard greens?
That’s a different food: a leafy green. Raw, it has 3.2 g of carbohydrate per 100 g and 1.9 g of fiber, according to TACO, in the same range as other greens in the table, such as raw collard greens (4.3 g). The vegetable table has the full list.
If you have high blood pressure, diabetes, or another condition, take medication, or are pregnant or breastfeeding, talk to a doctor before changing your diet. It’s also worth reading about the risks and precautions of the ketogenic diet.
Sources
- Harvard T.H. Chan School of Public Health, The Nutrition Source: Diet Review: Ketogenic Diet for Weight Loss
- U.S. Department of Agriculture (USDA), FoodData Central, SR Legacy
- TACO – Tabela Brasileira de Composição de Alimentos, 4ª edição revisada e ampliada (NEPA/Unicamp)
Mariana is passionate about a healthy lifestyle.
