Swapping butter for tub margarine and heart attack risk in women
What it found
Replacing one teaspoon of butter a day with tub margarine was linked to a small drop in heart attack risk among older women.
The link was stronger in women who used only one type of spreadable fat.
What they found
Studies in people
Heart attacks and tub margarine
When all users were grouped together, swapping one teaspoon of butter a day for tub margarine was linked to a small drop in heart attack risk. Swapping stick margarine for tub margarine showed a similar small drop.
Stronger links in single-fat users
Among women who used only one kind of spreadable fat, the link to fewer heart attacks was stronger. Swapping butter for tub margarine or stick margarine for tub margarine both showed larger drops in risk.
Other heart and stroke outcomes
For total coronary heart disease, strokes caused by blocked blood flow, and overall artery disease, the results pointed in the same direction. However, the ranges around these numbers were wide, so the findings were less certain.
Low-fat margarine swaps
Swapping butter for low-fat margarine was not linked to any benefit for heart attack risk. The authors say this might be because the ingredients in low-fat margarine vary widely.
Other findings
Fat makeup of the spreads
Butter is about 51% saturated fat and 3% trans fat. Stick margarine has 15% to 21% trans fat. Tub margarine has much less of both, with 14% saturated fat and 5% trans fat.
What the authors conclude
- They suggest that replacing butter or stick margarine with tub margarine may be linked to a lower chance of having a heart attack when people eat spreadable fats.
- The authors call for future studies that measure fat intake more than twice and look at real health outcomes.
How it was done
Health groups advise eating less saturated fat and trans fat to lower heart disease risk. The authors wanted to see if swapping butter or stick margarine for tub margarine might change that risk over time.
They followed 71,410 women aged 50 to 79 for an average of 13.2 years. The women reported what fats they used at the start and again three years later. The researchers then calculated what might happen if each woman swapped one teaspoon of butter a day for tub margarine.
What it can’t tell you
- Because this study followed people over time rather than randomly assigning their diets, it can show a link but cannot prove that the swap itself caused fewer heart attacks.
- The women reported their own food choices, which means the amounts of butter and margarine they ate might not be exact.
Who paid
- Funding
- Funded by NHLBI NIH HHS; WHI NIH HHS; NIA NIH HHS (from the PubMed record).
- Authors work at
- Brown University, RI; Memorial Hospital of Rhode Island, RI; and Blood Institute, MD
The paper
- Title
- Theoretical Effects of Substituting Butter with Margarine on Risk of Cardiovascular Disease
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Liu Q, Rossouw JE, Roberts MB, et al (2017). Theoretical Effects of Substituting Butter with Margarine on Risk of Cardiovascular Disease. Epidemiology (Cambridge, Mass.). doi:10.1097/EDE.0000000000000557Free full textPubMed 27648593DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error