A Diet High In Saturated Fat Raises Risk For Blood Clots

I like this study because it investigated the effect of background diet - in this case, the effect of diets containing different types of fat on blood coagulation, that is, how readily the blood clots:

Chronic Dietary Fat Intake Modifies The Postprandial Response Of Hemostatic Markers To A Single Fatty Test Meal, American Journal of Clinical Nutrition, February, 2008

It concluded:

"The use of a dietary model rich in SFA creates a more procoagulant environment than does a model that includes MUFA or [PUFA] as the source of fatty acids."

SFA: Saturated fatty acid, e.g. butter, cheese
MUFA: Monounsaturated fatty acid, e.g. olive oil
PUFA: Polyunsaturated fatty acid, e.g. corn oil, nuts

Design

Six markers for coagulation, in addition to blood lipids, were measured in 20 healthy young men after they consumed one of three diets for a month (it was a crossover design):

1) Saturated-fat-rich diet (SFA diet, primarily butter, about 3.5 tablespoons/day)

• 15% of energy as protein
• 47% of energy as carbohydrate
• 38% of energy as fat (22% SFA, 12% MUFA, 4% PUFA - of which 0.4% was omega-3)

2) Monounsaturated-fat-rich diet (MUFA diet, primarily olive oil, about 5 tablespoons/day)

• 15% of energy as protein
• 47% of energy as carbohydrate
• 38% of energy as fat (10% SFA, 24% MUFA, 4% PUFA - of which 0.4% was omega-3)

3) Omega-3-rich diet (N3 diet, primarily walnuts, about 18 halves/day)

• 15% of energy as protein
• 55% of energy as carbohydrate
• 30% of energy as fat (10% SFA, 12% MUFA, 8% PUFA - of which 2% was omega-3)

Diets were fed to participants (lots of control there) for 28 days, at the end of which a meal rich in the specific fat for each group was administered and blood was tested.

Results

Fasting State (12 hours after eating):

• Total cholesterol was higher after the SFA-rich diet than after the N3 and MUFA diets.
• LDL cholesterol was higher after the SFA-rich diet than after the N3 and MUFA diets.

Postprandial State (4 hours after eating):

• "The MUFA or N3 meals lowered concentrations of factor VII coagulant activity, although the reduction was greater after the MUFA-enriched meal."
• "The concentration of PAI-1 (encourages blood clotting) was greater after the SFA meal than after the other 2 meals."
• A fatty meal, no matter the type of fat, increased coagulation markers postprandially.

Of Note

1. "[Monounsaturated fats (olive oil) and omega-3 fats] are more easily cleared from the plasma than [saturated fats] due to their conformational structure."
   
2. "Our group previously showed that consumption of a MUFA-rich diet (rich in olive oil) improves sensitivity to insulin and reduces insulin and PAI-1* concentrations in comparison with SFA-rich diets."
   
   In fact, this study found higher concentrations of PAI-1 after consumption of the saturated-fat meal than the MUFA or omega-3 meals. And those higher concentrations stayed in the blood longer then they did after the other meals.
   
   * PAI-1 is plasminogen activator inhibitor-1. It inhibits the breakdown of blood clots. It's not the best thing to have in the blood if clotting is a problem.
   
3. "Some of the results we obtained may depend on minor components of the various foods we used rather than on the nature of their fats. Walnuts, for example, are a source of L-arginine, the original precursor of nitric oxide, so that an increase in nitric oxide might help to create a less proinflammatory and procoagulatory environment. For its part, virgin olive oil contains phenols in its nonsaponifiable part, and these have shown vasodilatory and anticoagulant effects during the postprandial phase.
   
   Such that ... "... part of the effects showed after the consumption of this diet were not due to its fatty acid composition but to the minor compounds present in virgin olive oil."

Take-home message for me ... it's best to limit meals high in saturated fat.
________ Photo: Bix