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Is Mayo Bad for You? A Case for America’s Favorite Keto-Friendly Condiment

By Fitoru | 11 August 2020
Keto mayo in a glass bowl

Mayo is often maligned as a high-calorie, high-fat condiment that can also poison you with bacteria if left out for too long. While that is all technically true—it is high in calories (94 per 1 tablespoon), high in fat (10 grams per tablespoon), and can get you sick if left unrefrigerated for over 2 hours—mayo is also a keto-friendly condiment that offers up certain nutrients depending on makeup. So…is mayo bad for you? Not in moderation, not if stored and prepared properly, and not if you keep the ingredients clean and free of additives, preservatives, and unhealthy oils. Let’s find out how!

What Goes Into America’s Favorite Keto-Friendly Condiment?

What condiment sells the most in America? Not mustard. Not ketchup. You guessed it…mayonnaise! 

You’re slathering it on your tuna and chicken salads and using it to make deviled eggs and homemade tartar sauce, shouldn’t you know what’s in it? 

Mayo is a mix of egg yolk, oil, and an acidic liquid like vinegar or lemon juice, with a dollop of mustard depending on the brand. The egg yolk is the emulsifier that binds the liquid with the oil to create a stable emulsion you can use to flavor up your sandwiches and potato salads.

Although it has a high fat content, it’s low in saturated fat and rich in healthy monounsaturated and polyunsaturated fats. 

According to the USDA, 1 tablespoon of mayonnaise = 

  • Total Fat 10 g
    • Saturated fat 1.6 g
    • Polyunsaturated fat 6 g
    • Monounsaturated fat 2.3 g

These healthy fats have been shown to help promote heart health and protect against heart disease.

Is Mayo Bad for You?

Mayo’s good or bad factor mostly depends on the type of oil it’s made with. America’s most popular commercial mayonnaise brands, like Best Foods, Hellman’s, Heinz, and Kraft, are made with soybean oil (or soy oil). Vegetable oils like soy oil are problematic for a few reasons. 

First, soybean oil is heavily processed and made from genetically modified soybeans. That’s strike one.

Strike two is that soybean oil is high in omega-6 essential fatty acids…higher even than canola oil. While omega-6 fats are associated with health benefits, such as promoting cardiovascular health, when we consume too many alongside too few omega-3 fatty acids, an imbalance occurs that can stoke the flames of chronic inflammation. 

Nutritionists recommend limiting your consumption of foods high in omega-6 while increasing your consumption of omega-3s. Mayo made with soybean oil isn’t the best option for the health-conscious eater. 

When choosing a mayo, look for a brand that uses a healthier oil, like olive oil, avocado oil, or coconut oil. 

Want a mayo that’s even more keto fabulous? Make your own homemade keto mayo using MCT oil. Recipe is down below!

What About Reduced or Low-Fat Mayo?

We can see the allure of a low-fat mayonnaise for people not following a ketogenic diet, but we can’t recommend it. 

That’s because light mayos trade in the fat for starches and sugars. Take Miracle Whip, for example. One of its selling points is that it has half the fat of mayo. What they don’t tell you is that it’s super high in sugars, including the most dangerous of all—high fructose corn syrup! Definitely not scaling up on wellness with low-fat mayo.

What About Vegan or Dairy-Free Mayo?

There’s nothing wrong with vegan or dairy-free, although you may not get quite the creamy consistency. Check the ingredients list carefully, because many vegan mayo alternatives use canola or soy oil as the base and may add preservatives and other additives, like brown rice syrup, which is low in fructose but acts like 100% glucose in your body!

Homemade Keto Mayo Recipe

Food Safety: Will Mayo Make Me Sick?

Raw eggs are susceptible to bacterial growth and can breed salmonella, but any regular mayonnaise you can buy in the United States is made from pasteurized eggs. The acidic nature of lemon and vinegar also helps to contain bacterial growth and keep your mayonnaise safe. However, mayonnaise and any food product made of mayonnaise should not spend more than 2 hours unrefrigerated.

To make sure your mayonnaise is free of bacteria, discard any opened jar after 2 months. 

When it comes to homemade mayo, the rules are a little different. A 2012 study published in the Journal of Food Protection found that it has a greater likelihood of containing salmonella bacteria (1). Food experts recommend pasteurizing your eggs in 140° F water for 3 minutes before whipping up your homemade mayonnaise.

Homemade Keto Mayo Recipe

For full control over your mayo ingredients and to add MCT oil for an energy and ketone boost, why not make your own mayo? Here’s our preferred recipe:


  • 1 egg yolk
  • 3 teaspoons lemon juice
  • 1 tablespoon Dijon mustard
  • 1/4 teaspoon salt
  • 1 teaspoon water
  • 1/2 cup MCT oil
  • 1/4 cup olive oil


  1. Whisk egg yolk, Dijon mustard, and lemon juice.
  2. Add in a teaspoon of water and salt and whisk some more. 
  3. While whisking (it’s easiest to use the whisk attachment on an immersion blender), add in a few drops of oil bit by bit. Wait until the mixture thickens before increasing the speed at which you add the oil. 
  4. Keep whisking until all oil has been added and emulsification achieved. The mayo should be thick and full of creaminess.
  5. Store in an airtight container in the fridge for 3-4 days. 


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