Question: How do the health effects of butter and margarine compare?
Short answer: There is no convincing evidence to say that either butter or margarine is harmful or beneficial for health. Or, according to Harvard Medical School:
Today the butter-versus-margarine issue is really a false one. From
the standpoint of heart disease, butter remains on the list of foods
to use sparingly mostly because it is high in saturated fat.
Margarines, though, aren't so easy to classify. The older stick
margarines turned out to be clearly worse for you than butter. Some of
the newer margarines that are low in saturated fat, high in
unsaturated fat, and free of trans fats are fine as long as you don't
use too much.
The summary of recent evidence suggests that butter consumption, despite being high in saturated fat, is not associated with increased health risk. On the other hand, high total dairy intake has been associated with increased risk of prostate cancer. It is not clear which component of dairy may be associated with cancer, though.
Is Butter Back? A Systematic Review and Meta-Analysis of Butter Consumption and Risk of Cardiovascular Disease, Diabetes, and Total Mortality (PLoS One, 2016)
In conclusion, the available evidence indicates small or neutral
associations of butter consumption with all-cause mortality, CVD, and
type 2 diabetes. (CVD = cardiovascular disease)
Dairy consumption and CVD: a systematic review and meta-analysis (British Journal of Nutrition, 2016):
The results of this meta-analysis of prospective cohort studies have
shown that dairy consumption may be associated with reduced risks of
CVD, although additional data are needed to more comprehensively
examine potential dose-response patterns.
Dairy and PROSTATE cancer:
Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies (AJCN, 2015):
High intakes of dairy products, milk, low-fat milk, cheese, and total,
dietary, and dairy calcium, but not supplemental or nondairy calcium,
may increase total prostate cancer risk. The diverging results for
types of dairy products and sources of calcium suggest that other
components of dairy rather than fat and calcium may increase prostate
Dairy products intake and cancer mortality risk: a meta-analysis of 11 population-based cohort studies (Nutrition Journal, 2016):
The current analyses showed that higher total dairy, milk, yogurt,
butter and skim/low-fat milk intake was not associated with increased
cancer mortality risk, while exposure to highest dose of whole milk
intake increased about 50 % of prostate cancer mortality risk.
Dairy and TESTICULAR cancer:
Dairy Consumption and Risk of Testicular Cancer: A Systematic Review (Nutrition and Cancer, 2018):
There is no consistent evidence to support the premise that dairy
product consumption is associated with the risk of TC development.
Dairy and COLORECTAL cancer:
Association Between Dairy Product Consumption and Colorectal Cancer Risk in Adults: A Systematic Review and Meta-Analysis of Epidemiologic Studies (Advencec in Nutrition, 2019):
In conclusion, high consumption of total dairy products and total milk
was associated with a lower risk of developing CRC.
Some time ago, the problem with margarines was their high trans fat content, but this has changed:
Fat composition of vegetable oil spreads and margarines in the USA in 2013: a national marketplace analysis (International Journal of Food Sciences and Nutrition, 2016):
This national 2013 survey shows that the fat quality of
vegetable-oil-based spreads in the US substantially improved over the
last decade. This is reflected by a significant removal of trans fat,
a decrease in solid fat (saturated-fatty acids plus trans-fatty
acids), and an increase in the proportion of unsaturated fat. In 2013,
the majority of US branded spreads (86% by sales volume), and in
particular soft spreads in a tub format (99% by sales volume), no
longer contained partially hydrogenated vegetable oils.
There is no clear evidence to say that margarines are better than butter for health:
Theoretical effects of substituting butter with margarine on risk of cardiovascular disease (Epidemiology, 2017):
This theoretical dietary substitution analysis suggests that
substituting butter and stick margarine with tub margarine when
spreadable fats are eaten may be associated with reduced risk of
In conclusion, it may not be possible to say which is better -- butter or margarine -- just from the studies, so everyone can judge this based on what your body and intuition tells you about what's good for you - something that is good for someone may not be good for you.