Friday, February 26, 2010

The grapefruit--one way to battle winter

As the snow keeps drifting down, the wind keeps a blowing, and the gray skies ever make me desire a personal psychiatric consult, the citrus aisle of the grocery store is a welcomed reminder that there are palm trees and sanity in blessed parts of the United States of America.  As you can tell from repeated posts and reminders, I’m not really a fan of winter.  I particularly disdain the bleak species where the snow turns black and there’s no topographic variation to permit skiing or mountainous exploration.***

I have employed a variety coping mechanisms for the seasonal blahs.  Tactics have included the evasive, fleeing the northern hemisphere in December for summery South America for six months; the illuminating, having my fiancĂ© design and build me a “happy lamp” as a sun substitute; and the caloric, particularly baking.

A less proud moment of winters past may have involved an entire chocolate layer cake topped with toasted walnuts and about a pound of homemade buttery caramel that I ate—alone.  (At least I completed an Olympic distance triathlon that summer.)  Now I moderate a bit better, but I still love to bake during the winter.  Benefits of winter baking include, admittedly, the cold weather allowing the oven to steam the windows Titanic style, and of course, the citrus.  Not only are the lemons and oranges beautiful, but the grapefruits are brilliant in baked goods.

The grapefruit, the beloved seemingly benign diet food of America also has a more mischievous side.  Grapefruit juice can be a bad player when taken with a variety of medications.  This discovery, like many scientific discoveries was hobbled upon coincidentally.

 In the 1980s in attempts to study the interaction between ethanol and a popular blood pressure medication, scientists decided on a Saturday night to make a felodipine Cosmopolitan with grapefruit juice to help the booze go down a bit better [1].  When they ran the experiment, they found that patients who took the drug with the cocktail had significantly lower blood pressures than those who had no alcohol.  Somebody astutely suggested it was the juice, not the liquor that caused such drastic changes in the drug metabolism.

Since this time, the grapefruit juice/medication interaction has been further explored.  [2,3].  Many medications are metabolized through an enzymatic pathway.  It appears that grapefruit juice reduces the prevalence of the enzyme CYP3A4 part of the cytochrome P450 in both the gut and the liver.  This allows for more medicine to be absorbed in the intestine and allows for medicines to linger in greater concentrations.  This can exacerbate toxic effects of  multiple drugs. 

A list of common medications that interact with grapefruit are listed here.  If you are concerned, please talk to your doctor.  If you are not taking any of these medications, feel free to participate in the construction and destruction of a luscious grapefruit lemon bar.  The benefit of the grapefruit is a complex sweetness with a less harsh tartness that I find many lemon bars have.  The crust is a modified shortbread recipe, so it is crisp, crumbly and light, with a bit of sour cream to echo the acidity in the filling.  The filling is more of a curd than a sturdy baked custard, so these treats are best eaten with a fork after refrigerated overnight.  The curd would also work great on toast or as a filling for cakes or cookies so feel free to separate the elements and work with what pleases you.

Grapefruit lemon bars

Shortbread Crust
Adopted from Joy of Cooking
¾ cup unsalted butter (1 ½ sticks) softened
2 tbsp sour cream
¼ cup confectioner’s sugar (powdered sugar)
2 tbsp granulated sugar
¼ tsp salt
1 ½ cups all purpose flour

Preheat oven to 300 degrees.  In large bowl beat all ingredients minus flour.  Stir in flour.  Light knead until blended.  In 8x8 baking pan with fingers press dough into bottom and up around the edges about ¾”.  Bake for about 35 minutes or until lightly browned and darker at the edges.  While baking, make the curd filling.  Allow to cool slightly for about 5 minutes and add the curd.  Refrigerate for 4-5 hours or until cool and set.  Sprinkle with powdered sugar and enjoy!

Grapefruit Curd
Adopted from James Peterson’s Baking

Juice and zest from one ruby red grapefruit (about 1 cup juice)
Juice and zest from one lemon
4 eggs
¾ cup granulated sugar
1/2 cup plus 2 tbsp unsalted butter cut into tablespoon pieces

Set a saucepan of water over medium heat and bring to a simmer.  In a heatproof bowl that will fit over pan, whisk together eggs and sugar for about 2 minutes until pale.  Then whisk zests and juice.  Set the bowl over the saucepan.  Stir constantly with a whisk for about 8 minutes or until the mixture starts to thicken.  Add the sliced butter, one piece at a time and stir constantly.  Cook for about 2 minutes longed.  Remove from heat.

***On a side note completely unrelated to the core of this essay, I have just undergone the most unbelievable ritual to prove that winter is evil.  Coincidentally, my car and my fiancĂ©’s car break simultaneously.  Our lovely repair shop lends us a loaner.  After spending an hour driving through blustery conditions to drop him off and then drive to the hospital, I roll down the window to take a parking ticket. The window falls into the door with impressive speed and doesn’t come out.  I then proceed to drive through downtown with no window while it snows into the car.

1. Bailey D et al.  Ethanol enhances the hemodynamic effects of felodipine.  Clin Invest Med 1989: 12: 357-362.
2. Dahan A et al.  Food Drug interaction: grapefruit juice augments drug bioavailability—mechanism, extent and relevance.  2004.  European journal of Clinical Nutrition.  58, 1-9.

3.  Bailey D et al.  Grapefruit Juice-Drug Interactions.  1998.  British Journal of Clinical Pharmacology.  46: 101-110.


  1. Such great writing! Thanks!

  2. These look and sound great. Totally just got my tastebuds ready for summer!