ZOE runs the largest nutrition science study in the world. We analyze how different people respond to thousands of foods and publish this research in top scientific journals, including Nature Medicine.
Unsalted butter contains 81.5% fat. It’s less processed than plant spreads but does contain saturated fats.
Based on measurements of over 20,000 individuals, our scientists predict that for 64% of the people, it’s OK to eat butter regularly — about every other day — but not every day, and large quantities may have a negative impact.
For 36% of people, having butter from time to time — around 2–3 days per week — in normal quantities is fine, but there are healthier swaps and alternatives. That’s because eating butter can lead to long periods of high blood fat for some people, which is not good for your health.
At ZOE, we know that everyone responds differently to food.
You can take a free quiz to learn more about finding the best foods for you with our personalized nutrition program.
Read on to discover why butter is OK for many people but not a good choice for just over one-third.
Butter and blood fat
When you eat food that contains fat — like butter — your body breaks this down and absorbs it into your bloodstream as fat molecules called triglycerides. They are a source of energy for your body, and any excess triglycerides are stored in your fat cells, just like excess carbohydrates are.
Changes in blood fat or triglyceride levels after eating are normal. It’s usual to see a peak after around 4 hours, but the levels should return to normal after 6–8 hours.
Some types of fat are harder to clear from your blood than others, and some are also more likely to cause inflammation.
How quickly you can clear triglycerides from your blood is unique to you, and factors like your sex and your age are involved.
If people can’t clear the fat from their blood after eating butter within 6–8 hours, this may start a chain of reactions in the body that leads to inflammation.
If repeated over and over again, this increases the risk of long-term, serious health problems like cardiovascular disease and diabetes, as well as weight gain.
Butter and gut health
The trillions of bacteria and other microbes that live in your gut make up your gut microbiome. They help digest your food and provide important chemicals for your immune system and your overall health.
ZOE scientists have found 15 “good” gut microbes that are associated with indicators of good health and 15 “bad” gut microbes that are linked with worse health.
Bacteria mainly eat fiber and polyphenols in your meals. Butter does not contain either, but fats do interact with your bacteria.
There is evidence that some low-quality fats can damage the health of your gut microbiome, and that certain high-quality fats such as extra virgin olive oil promote the "good” bugs.
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Whether butter contributes to the health of your gut bacteria is not clear at the moment.
One of ZOE’s “good” gut bugs, called Valentina, doesn’t like butter. As ZOE’s research continues, we will discover more about the impact of butter on your gut health.
How our scientists measure if a food is good for you:
We measure the responses of thousands of people to different foods by collecting data about blood sugar and blood fat levels, the gut microbiome, inflammation, exercise, sleep, and more.
After you take our simple at-home test, we use artificial intelligence to compare the results to those of over 20,000 people who have taken part in our clinical studies.
Based on your unique data, we can score any food or meal as being good or not so good for you.
Butter and your body: It’s personal
Our research shows that how your body responds to the foods you eat is unique to you. Your blood sugar and blood fat metabolism, as well as your unique gut bugs, influence this.
With the ZOE program, you can find out how good butter is for you and your long-term health goals, based on the latest science. And if it turns out that it’s not great for you, we’ll suggest plenty of food swaps to help you find the best foods for your body.
Take our free quiz to find out more.
What could you eat that’s better?
Try swapping butter for extra virgin olive oil in your cooking, as this scores much better. Extra virgin olive oil is full of healthy unsaturated fat and polyphenols, which can lower your risk of chronic conditions like heart disease. It’s also good for your gut microbiome.
As an alternative to butter in your sandwich or on a cracker, you could try cheeses like cheddar, Swiss, and Parmesan. They generally score better than butter for your health. That’s because when microbes ferment milk and turn it into cheese, they actually make it healthier for your body.
Even though cheese is also high in saturated fat, research shows it does not have the same negative effects as butter.
Ready to learn about the best foods for you?
Butter, stick, unsalted. (n.d.). https://fdc.nal.usda.gov/fdc-app.html#/food-details/789828/nutrients
Comparison of the impact of SFAs from cheese and butter on cardiometabolic risk factors: a randomized controlled trial. The American Journal of Clinical Nutrition. (2017). https://pubmed.ncbi.nlm.nih.gov/28251937/
Extra-virgin olive oil and the gut-brain axis: influence on gut microbiota, mucosal immunity, and cardiometabolic and cognitive health. Nutrition Reviews. (2021). https://academic.oup.com/nutritionreviews/article/79/12/1362/6133931
Microbiome connections with host metabolism and habitual diet from 1,098 deeply phenotyped individuals. Nature Medicine. (2021). https://www.nature.com/articles/s41591-020-01183-8