Saturated, Unsaturated and Trans Fats Explained
What saturated, unsaturated and trans fats are, which oils and spreads contain how much (USDA values), and what health bodies and trials say about swapping one for another.
Content last updated . This page has not been medically reviewed.
Every oil, butter and spread is a mix of fats. The mix decides how it behaves in the pan and how it relates to blood cholesterol. This guide explains the three main families in plain words, shows what USDA measured in common fats, and sets out what health bodies and research say. It is information, not a prescription for you.
Read this first
- Saturated fat is the family health bodies ask us to limit. The Dietary Guidelines and WHO both give a ceiling of 10% of daily calories. [1] [2]
- Unsaturated fat (monounsaturated and polyunsaturated) is the family health bodies suggest as the swap for saturated fat. [2] [3] [4]
- What you swap matters. The AHA advisory found that replacing saturated fat with refined carbohydrates and sugars was not linked to lower heart disease rates. [5]
- Trans fat from partially hydrogenated oils has been removed from most US foods since 2018. Small amounts occur naturally in dairy and meat. [6]
- Evidence has gaps. Pooled trials point one way (swapping helps), while large pooled observational studies of saturated fat alone found no clear link to heart disease or death, with very low certainty. [5] [7] [8]
The main families
| Family | What it means in plain words | Typical food sources, as the sources describe them |
|---|---|---|
| Saturated fat | Fats that are usually solid at room temperature. | Mainly animal foods, plus coconut, palm and palm kernel oils. [3] NHS lists fatty meat, butter, ghee, lard, cream, hard cheese, palm oil and coconut oil. [4] |
| Monounsaturated fat | One kind of unsaturated fat, liquid at room temperature. | Olive, peanut and canola oils, avocados, and nuts such as almonds and pecans. [3] |
| Polyunsaturated fat | The other unsaturated kind. It includes omega-3 and omega-6 fats, which the body cannot make. | Sunflower, corn, soybean and flaxseed oils, walnuts, flaxseed and fish. [3] |
| Trans fat | Made when liquid oils are hydrogenated, and found naturally in small amounts in beef and dairy fat. | Fried foods, baked goods, shortening and stick margarine, as listed by MedlinePlus. [9] See the trans fat guide. |
What USDA measured in common fats
The numbers below are from USDA FoodData Central (SR Legacy, April 2018 release). Each food is one USDA item, so a different olive oil or brand will differ a little. A tablespoon is the USDA household portion of 12.8 to 14.2 g, as listed per item. [10]
| Fat (USDA item) | Saturated, per 100 g | Monounsaturated, per 100 g | Polyunsaturated, per 100 g | Saturated, per tablespoon | Energy, per tablespoon |
|---|---|---|---|---|---|
| Canola oil (172336) | 7.4 g | 63.3 g | 28.1 g | 1.0 g | 124 kcal |
| Flaxseed oil, cold pressed (167702) | 9.0 g | 18.4 g | 67.8 g | 1.2 g | 120 kcal |
| Sunflower oil, linoleic (171025) | 10.3 g | 19.5 g | 65.7 g | 1.4 g | 120 kcal |
| Avocado oil (173573) | 11.6 g | 70.6 g | 13.5 g | 1.6 g | 124 kcal |
| Olive oil, salad or cooking (171413) | 13.8 g | 73.0 g | 10.5 g | 1.9 g | 119 kcal |
| Soybean oil (171411) | 15.7 g | 22.8 g | 57.7 g | 2.1 g | 120 kcal |
| Lard (171401) | 39.2 g | 45.1 g | 11.2 g | 5.0 g | 115 kcal |
| Palm oil (171015) | 49.3 g | 37.0 g | 9.3 g | 6.7 g | 120 kcal |
| Butter, salted (173410) | 51.4 g | 21.0 g | 3.0 g | 7.3 g | 102 kcal |
| Ghee (butter oil, 173412) | 61.9 g | 28.7 g | 3.7 g | 7.9 g | 112 kcal |
| Coconut oil (171412) | 82.5 g | 6.3 g | 1.7 g | 11.2 g | 121 kcal |
Per-tablespoon figures are calculated from the per-100-g values and the USDA tablespoon weight. [10] For comparison, the FDA Daily Value for saturated fat is 20 g, based on a 2,000-calorie diet, so one tablespoon of coconut oil is above half of it. [11] Pure oils all come to roughly 115 to 124 kcal a tablespoon, so swapping one oil for another changes calories very little. Butter and margarine-type spreads are lower per tablespoon in USDA's data. [10]
What health bodies say
| Body | What it says, as read |
|---|---|
| US Dietary Guidelines 2025 to 2030 | Saturated fat should not exceed 10% of daily calories. It names olive oil as an oil with essential fatty acids and also lists butter and beef tallow as options, and says more high-quality research is needed on which fats best support long-term health. [1] |
| Harvard Nutrition Source commentary on those guidelines | Notes the 10% limit was kept, says the type of fat matters most (replace saturated with unsaturated), and calculates that about 22 g is the limit on a 2,000-calorie diet. A tablespoon of butter has 7 g and one of beef tallow 6 g. [12] |
| WHO | Saturated fat at or below 10% of energy and trans fat at or below 1%. Prefers unsaturated fats such as fish, avocado, nuts and sunflower, soybean, canola and olive oils. [2] |
| NHS (UK) | Men should have no more than 30 g and women no more than 20 g of saturated fat a day. Adults should have no more than about 5 g of trans fat a day. [4] |
| American Heart Association advisory (2017) | Concludes strongly that lowering saturated fat and replacing it with unsaturated fats, especially polyunsaturated, will lower heart disease, within a healthful pattern such as DASH or Mediterranean. [5] |
The Harvard Nutrition Source page also says the AHA suggests 8 to 10% of calories from polyunsaturated fat. [3] Sources give different ceilings (for example the Harvard page says the AHA suggests a lower limit than the Dietary Guidelines), so ask your own clinician which target applies to you. [3]
What the research found
| Question | Finding | Strength |
|---|---|---|
| Cutting saturated fat | A Cochrane review of 15 randomized trials (about 59,000 people, at least 2 years) found about 21% fewer combined cardiovascular events (RR 0.79) with moderate-quality evidence, but little or no effect on deaths from any cause. Replacing with polyunsaturated fat or carbohydrate appeared useful. The effect of replacing with monounsaturated fat was unclear. [7] | Pooled trials, defined outcome |
| Swapping with polyunsaturated oil | The AHA advisory reports that trials replacing saturated fat with polyunsaturated vegetable oil cut heart disease by about 30%, similar to statins. [5] | Pooled trials plus observational |
| Saturated fat on its own | A pooled analysis of observational studies found saturated fat was not clearly linked to all-cause death (RR 0.99), heart disease deaths or total coronary heart disease. The authors rate the certainty as very low and the studies as varied. [8] | Observational, very low certainty |
| Trans fat | The same pooled analysis linked total trans fat to higher all-cause death (RR 1.34) and coronary heart disease (RR 1.21), mostly from industrial rather than ruminant trans fat. [8] | Observational, moderate certainty for heart outcomes |
These two sets of findings are not a contradiction. Trials ask "what happens when people change the fat they eat", and observational studies compare people who already eat different amounts. What each person replaces saturated fat with decides the result. [5] [8]
How to use this when you shop and cook
- Look at the fat that goes in place of another. Replacing butter with olive, canola or sunflower oil lowers saturated fat, while replacing it with refined starch does not help. [5]
- Check the Nutrition Facts label. The FDA says 5% DV or less of a nutrient per serving is low and 20% DV or more is high; saturated fat is one of the nutrients to get less of. [11]
- Trans fat has no % Daily Value on the label, because experts could not give a reference value. [11]
- For cooking choices see which cooking fat to choose and smoke points and cooking with oil.
- If you have a nut, peanut, sesame or soy allergy, ask your doctor whether a particular oil is suitable. Trouble breathing or swelling of the face or throat after eating needs a 911 (or local emergency number) call. See food allergy basics.
Related pages
Frequently asked questions
Are all saturated fats the same?
No. The sources we read group them together as one family, but the foods that contain them differ. A pooled analysis of food sources found milk, cheese, yogurt and butter were not clearly linked to higher death risk, while meat and processed meat were, with variable study quality. [13] Observational findings do not prove cause.
Is unsaturated fat always the healthier choice?
Health bodies suggest it as the swap for saturated fat. [2] [4] [5] The Harvard page notes that swapping saturated fat for refined carbohydrates offers little benefit. [3] Unsaturated oils are still dense in calories, about 120 kcal a tablespoon. [10]
How much saturated fat is too much?
Official ceilings are 10% of calories (US Dietary Guidelines and WHO) and, in the UK, 30 g for men and 20 g for women a day. [1] [2] [4] This is general information. Your clinician can advise a personal target.
Does natural trans fat in dairy count?
WHO says trans fat from industrial and ruminant sources is held to the same 1% limit, and calls the two equally harmful. [14] The pooled observational analysis found the heart link mainly for industrial trans fat. [8] The sources are not fully aligned, which is why the question is still being studied.
Which fat is best for the heart?
We did not find a single best fat in the sources read. Health bodies point to plant oils rich in unsaturated fat within an overall pattern such as Mediterranean or DASH. [5] See which cooking fat to choose.
References
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2025-2030 (summary document, section "Incorporate Healthy Fats"). Read 2026-10-24.
- World Health Organization. Healthy diet fact sheet. Read 2026-10-24.
- Harvard T.H. Chan School of Public Health, The Nutrition Source. Types of fat. Read 2026-10-24.
- NHS. Different fats in food. Read 2026-10-24.
- Sacks FM et al. Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association. Circulation 2017 (abstract read via Europe PMC). Read 2026-10-24.
- U.S. Food and Drug Administration. Trans fat. Page last updated 04/30/2024. Read 2026-10-24.
- Hooper L et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews 2020. Read 2026-10-24.
- de Souza RJ et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ 2015 (abstract read via Europe PMC). Read 2026-10-24.
- MedlinePlus. Facts about trans fats. Read 2026-10-24.
- U.S. Department of Agriculture. FoodData Central, SR Legacy (April 2018): items 172336, 167702, 171025, 173573, 171413, 171411, 171401, 171015, 173410, 173412, 171412. Values per 100 g and household portions as listed. Read 2026-10-24.
- U.S. Food and Drug Administration. How to understand and use the Nutrition Facts label. Read 2026-10-24.
- Harvard T.H. Chan School of Public Health, The Nutrition Source. Dietary Guidelines for Americans 2025-2030: progress on added sugar, protein hype, saturated fat contradictions. Read 2026-10-24.
- Food sources of saturated fat and the association with mortality: a meta-analysis. 2013 (abstract read via Europe PMC). Read 2026-10-24.
- World Health Organization. Trans fat fact sheet. January 2024. Read 2026-10-24.