Fried Food, Dangerous For The Heart


The consumption of French fries worldwide continues to rise and has even reached a peak of 11 billion kilos per year. The way it is cooked gives food a crunchy texture, but unfortunately, deep-frying has a negative impact on heart health.

french fries bad for you

A very greasy cooking method

Frying is a method of cooking that makes food particularly fatty. After a quick bath in oil, the fat content of potato increases from 0.1g to 12g! This can be explained by 2 mechanisms: the frying oil that replaces the water in the food evaporated during cooking1 and the absorption of oil during cooling2.

It is this last phenomenon that makes the finer the food, the fattier it is. Studies3 have shown that very thin French fries (for example, those from fast food restaurants) are three times fattier than their thicker counterparts.

It is recommended that fried food be mechanically stirred4 during cooling and then placed in a piece of absorbent paper5 to reduce absorption as much as possible. The salting of fried food immediately after leaving the bath is more controversial, however: even if it allows some of the fat to be removed, the consumption of salt that it generates is also harmful to the health of the heart...

Foods high in bad fats

This high lipid content, which can contribute to an excess energy balance, is all the more harmful since they are part of the "bad fats", known to attack the integrity of arterial walls6. This is due to the fats that are used during frying: those obtained from saturated fatty acids are more stable at high temperatures and therefore lead less to the formation of potentially toxic compounds.

Restaurants and households therefore logically tend to opt for oils that will remain intact longer. Some even choose animal fat (the famous "beef white") for the taste it gives to food, even though its saturated acid content beats all records! And consuming too much saturated fatty acids increases the risk of cardiovascular disease7-8.

Some factors further increase the fat content

Originally very greasy, frying can be even greasier. Industrial deep-frozen fries, which offer significant time savings, are always precooked from the wrong fats and are more porous than fresh fries. They absorb more oil during the second cooking than a raw fry. This also applies to the water or oil bleaching of homemade French fries.

The frying temperature also influences the final fat content of the fried food.

Above 200° C, the oil degrades, becomes less fluid, and penetrates food more easily9; below 140° C, frying time increases, as does oil absorption.


  1. Bouchon, 2009 ; Rossell J.B., 2001
  2. Saguy I.S., Dana D., 2003
  3. Rossell J.B., 2001 ; Ziaifar, 2008
  4. Bouchon, 2009
  5. Ziaiifar, 2008
  6. Ascherio A, Rimm EB, et al. Dietary fat and risk of coronary heart disease in men: cohort follow up study in the United States. BMJ ; 1996, 313, 84-90.
  7. McGee DL, Reed DM, et al. Ten-year incidence of coronary heart disease in the Honolulu Heart Program: relationship to nutrient intake. Am J Epidemiol, 1984, 119, 667-676.
  8. Kushi LH, Lew RA, et al. 1985. Diet and 20-year mortality from coronary heart disease. L'étude Irlande-Boston Diet-Heart Study. N Engl J Med, 1985, 312, 811-818.
  9. Bouchon, 2009, Ziaifar, 2008