Mustard is significantly healthier than mayonnaise by almost every nutritional measure. A teaspoon of yellow mustard has about 5 calories and zero fat, while a tablespoon of regular mayonnaise packs 94 calories and 10 grams of fat. Even accounting for the fact that people use more mayo per sandwich, the gap is enormous.
That said, the full picture is more interesting than a simple calorie count. Each condiment has specific nutritional trade-offs worth understanding, especially if you’re choosing between varieties or looking for ways to keep flavor without the downsides.
Calories and Fat Side by Side
The FDA sets different standard serving sizes for these two condiments, which reflects how people actually use them. Mustard’s reference amount is 1 teaspoon (about 5 grams), while mayonnaise’s is 1 tablespoon (15 grams). Even with that three-to-one difference in serving size, mayo still delivers nearly 20 times more calories per serving.
A teaspoon of spicy or yellow mustard contains 5 calories, no fat, no sugar, and no carbohydrates. A tablespoon of full-fat mayonnaise contains 94 calories and 10 grams of fat. In real-world use, most people spread at least a tablespoon of mayo on a sandwich, sometimes more. Swapping mayo for mustard on a daily sandwich can cut roughly 90 calories and 10 grams of fat from your lunch without changing anything else about the meal.
What Mustard Brings Beyond Low Calories
Mustard seeds are a source of compounds called glucosinolates, which break down into biologically active molecules during digestion. These compounds have documented anti-inflammatory and antimicrobial properties. Research published in the journal Molecules found that mustard seed extracts can help reduce inflammation and may lower the risk of cardiovascular disease. The seeds also contain small amounts of omega-3 fatty acids, which support heart and brain health.
Yellow mustard gets its color from turmeric, a spice that contains curcumin. Curcumin is one of the most studied anti-inflammatory compounds in food science. The amount of turmeric in a serving of mustard is small, though. Johns Hopkins Medicine notes that curcumin supplements contain far higher concentrations than what you’d get from foods flavored with the spice. So while the turmeric in mustard isn’t a therapeutic dose, it’s a modest bonus on top of an already low-calorie condiment.
Mustard also contains vinegar, which has a measurable effect on blood sugar. A study in the Journal of Diabetes Research found that vinegar reduced post-meal blood sugar spikes, lowered insulin levels, and decreased triglycerides in people with type 2 diabetes. The vinegar in a serving of mustard is a small amount, but for people eating mustard regularly, this is a subtle advantage mayo doesn’t offer.
The Case Against Mayo (and Where It’s Overstated)
Most commercial mayonnaise is made with soybean oil, egg yolks, and vinegar. The calories and fat are real concerns, but the type of fat matters too. Soybean oil is largely unsaturated, and it’s particularly rich in polyunsaturated fats, which can lower LDL (“bad”) cholesterol more effectively than the monounsaturated fats found in olive or avocado oil. So while mayo is calorie-dense, it’s not delivering the same heart risk as a condiment loaded with saturated fat.
One issue with soybean oil-based mayo is its omega-6 to omega-3 ratio. In commercial soybean oil mayo, this ratio is roughly 9.5 to 1. Most nutrition researchers consider a lower ratio, closer to 4 to 1 or less, to be better for reducing chronic inflammation. A heavy mayo habit can push your overall omega-6 intake higher, which is worth noting if the rest of your diet already leans heavily toward processed vegetable oils.
Watch the Sodium in Mustard
Mustard’s one nutritional weak spot is sodium. A two-teaspoon serving of French’s Classic Yellow Mustard contains 102 milligrams of sodium, which is 4% of the daily value. That sounds modest, but mustard adds up quickly if you’re generous with it across multiple meals. Dijon and stone-ground varieties can be higher. If you’re managing blood pressure or watching sodium intake, it’s worth checking labels rather than assuming mustard is a free pass.
Not All Mustards Are Equal
Yellow mustard and Dijon mustard are both essentially zero-sugar condiments. Honey mustard is a different story. It contains about 1 gram of sugar per serving, and many commercial honey mustard dressings (as opposed to the mustard itself) contain considerably more, along with added oils that bring the calorie count closer to mayo territory. If your goal is the health advantage of mustard, stick with yellow, Dijon, or stone-ground varieties and read the label on anything that says “honey” or “sweet.”
Avocado Oil Mayo Isn’t a Health Upgrade
Avocado oil mayonnaise has become a popular “healthier” alternative, but the Center for Science in the Public Interest found that it’s no healthier than regular mayo. The calorie and fat content are nearly identical. The main difference is the type of unsaturated fat: avocado oil is higher in monounsaturated fat, while soybean oil is higher in polyunsaturated fat. If anything, the polyunsaturated fats in regular soybean oil mayo are slightly better at lowering LDL cholesterol. You’ll pay more for avocado oil mayo without a meaningful nutritional return.
Practical Swaps That Work
The simplest swap is using mustard in place of mayo on sandwiches, burgers, and wraps. You lose the creamy texture but gain a sharper, more complex flavor with a fraction of the calories. For recipes where you need creaminess, mixing a small amount of mayo with a larger amount of mustard gives you the texture without the full caloric load. A 50/50 blend cuts the fat roughly in half while still feeling like a spread rather than a sauce.
For salad dressings, mustard-based vinaigrettes are dramatically lighter than mayo-based dressings like ranch or Caesar. A basic mix of mustard, olive oil, and vinegar gives you the anti-inflammatory benefits of all three ingredients. In potato salad or coleslaw, German-style recipes that use a mustard-vinegar base instead of mayo are lower in calories and hold up better in warm weather, since there’s no egg-based emulsion to spoil.