Health

7 diet studies reveal not all fats created equal

How scientists first linked fatty foods to high cholesterol, heart attack and stroke and why they started backing away from the claims.

A low-fat diet is supposed to keep us healthy. Or is it?

Here are some of the main studies that started the high-fat hypothesis and then called it into question. 

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  • Ancel Keys launched his landmark Seven Countries Study in 1958. It showed correlations between dietary fat and heart disease.

  • Large, cohort studies at Harvard in women in 1997 and men in 1996 looked at diets and suggested total fat was not associated with heart disease — but all fats were not created equal. It was suggested that saturated fat was probably harmful and polyunsaturated fat from vegetable oil or fish oil were likely protective.

  • In 1997, the DASH trial of a higher carbohydrate, low-saturated fat dietary pattern suggested benefits on blood pressure.
  • The OMNI Heart trial published in 2005 showed that a low carb, higher monounsaturated fat version of the DASH diet from eating olive oil and nuts for example might be even better.
  • The 2013 PREDIMED study in Spain showed that a Mediterranean diet rich in monounsaturated fat reduced cardiovascular disease risk by 30 per cent after about five years of followup compared with a control diet that advised reduced dietary fat. 
  • Jakobsen's cohort study on replacing saturated fat with "high" glycemic index carbohydrates raised the risk of heart disease by 33 per cent. 

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