Healthy foods

Another study has questioned whether saturated fat itself really has a role in elevating heart disease risk and suggests that even good sources of carbohydrates are likely to be more harmful in terms insulin resistance and heart health.

The study, carried out by Ohio State University, involved 16 participants which were monitored over 21 weeks. Participants started on an initial low carbohydrate run-in diet (under 50g of carbohydrate per day) and then went onto a series of diets in which the saturated fat content was steadily decreased and carbohydrate intake increased.

Week Carbohydrate intake Saturated fat intake
1 to 3 (run in diet) Under 50g
4 to 6 47 g 84 g
7 to 9 83 g 76 g
10 to 12 131 g 71 g
13 to 15 179 g 61 g
16 to 18 251 g 49 g
19 to 21 346 g 32 g

The diets were each set to meet a total of 2,500 kcal per day and each diet included 130g of protein. By the end of the study, the level of carbohydrate was set to meet 55% of energy intake and therefore meets the recommended intake set for the American diet.

The carbohydrates in the diet were chosen to meet the dietary recommendations of being low GI and generally whole grain sources.

The results produced a number of interesting measures:

  • Weight loss started out swiftly on the low carbohydrate diet and levelled off as more carbohydrate was introduced
  • Insulin resistance improved greatly but initial improvements on the very low carbohydrate diet started to be erased with the introduction of more carbohydrate
  • Cholesterol figures showed mix trends with the most clear trend being an increase in triglyceride levels as carbohydrate levels were increased
  • Blood pressure displayed an interesting trend with systolic blood pressure decreasing throughout the study whilst diastolic blood pressure grew with increasing carbohydrate intake

In addition the researchers found that levels of palmitoleic acid in the blood increased as carbohydrate intake increased. Higher levels of palmitoleic acid have been linked with increased insulin resistance, obesity and heart disease.

The researchers conclude that eating higher intakes of saturated fat do not contribute to higher levels of saturated fat in the blood. Furthermore, eating higher intakes of carbohydrate increased levels of triglycerides and palmitoleic acid, both of which are associated with negative health outcomes.