Are you a Turkey When it Comes to L-Tryptophan?

Here in the U.S., Thanksgiving is the start of the holiday season and most people look forward to the Thanksgiving dinner all year long – turkey, mashed and/or sweet potatoes, gravy, cranberry sauce and of course, pie.  Yummmm.  You could easily consume over 2000 calories in one sitting (without even counting the alcohol calories)!!!

Although turkey is often cited as the culprit in the after-dinner lethargy, is gobbling up all that turkey really to blame?

Well, not exactly.  Turkey does contain L-tryptophan, an essential amino acid with a documented sleep inducing effect.  When we eat foods that contain L-tryptophan, this amino acid travels in the blood from the digestive system and later enters the brain.  The brain then changes the L-tryptophan into serotonin – which calms us down and helps us sleep. 

However, L-tryptophan can really only make a person tired right away if it is eaten or taken by itself without any other amino acids.  And the protein in turkey contains plenty of other amino acids – and that’s not including all the other food on the Thanksgiving table. 

It’s worth noting that other foods contain close to the same amount of tryptophan than turkey (0.333 grams of tryptophan per 100 gram edible portion), including chicken (0.292 grams per 100 gram edible portion), pork and cheese.  As with turkey, other amino acids are present in these foods besides tryptophan, so they don’t make you sleepy either. 

It’s More Than Just Tryptophan

Instead of just turkey being to blame, nutrition experts and scientists believe that one reason you may feel sleepy after your Thanksgiving feast is actually that carbohydrate-rich meal that leads to a much higher serotonin synthesis than does L-tryptophan found in turkey.  Think of all those starchy, sugar-containing foods like bread, yams, potatoes, pumpkin pie, etc. 

You see, these carbohydrates stimulate the pancreas to secrete insulin.  When this occurs, some amino acids that compete with tryptophan leave the bloodstream and enter muscle cells.  This causes an increase in the relative concentration of tryptophan in the bloodstream.  Serotonin is synthesized and you get that sleepy feeling.

And, eating a big Thanksgiving dinner causes increased blood flow to the stomach (needed to help digest the meal) and less blood flow to the brain. 

Not only that, but the fats in the Thanksgiving dinner also slow down the digestive system.  Fats also take a lot of energy to digest, so the body will need to redirect blood to your digestive system to tackle the job. 

And if that isn’t enough, add in the alcohol, which is a central nervous system depressant, and a nap is just around the corner!

You’ve Got That Sleepy Feeling!

When your stomach is full, blood is directed away from your nervous system because it takes such a large amount of energy to digest such a large meal.  So what happens next??  You will want to take a nap after any large meal, particularly if it is high in fats and carbohydrates.  So, it’s really the combination of the type of food, the amount of food, alcohol and the group atmosphere. 

A Few Holiday Tips…

So, what can you do to avoid the huge calorie input and the resulting lethargy?  It can be a real challenge if you are watching your waistline as well, so the following are some eating tips to still look good and feel good and be healthier after the Thanksgiving dinner without having to deprive yourself….

• Eat at least 1 or 2 small meals earlier in the day:  We often eat faster and more when we are hungry – therefore eat a light breakfast and lunch on the day to avoid overeating at dinner time.
• Try a smaller plate:  If you want to cut calories, choose smaller bowls and plates.  Less food will make its way into your mouth.
• This is not an all-you-can-eat buffet:  Fill your plate half with vegetables, one quarter with lean meat (turkey breast), and the rest with a starch of your choice.  Eat slowly and stop when you are full.
• Go skinless:  Choose your 4-6 oz. turkey portion skinless to slash away some fat and cholesterol.
• Smaller portions:  Along with the smaller plate, go for smaller portions.  Sample the different foods in moderation.
• Limit high fat items:  High fat food items can be found in fried and creamy dishes as well as cheese-filled casseroles in a traditional Thanksgiving meal.  For instance, mashed potatoes are usually made with butter and milk; green bean casseroles are often prepared with cream of mushroom soup (also high in salt), candied yams are loaded with cream, sugar and marshmallows.  If you cannot control the ingredients that go into a dish, simply limit yourself to a smaller helping size.  Again, moderation is the key.
• Drink plenty of water:  alcohol can dehydrate your body as can caffeine if you don’t use it regularly.  Drink calorie-free water to help fill up your stomach and keep you hydrated. 

If you are cooking Thanksgiving dinner:

• Substitute high fat ingredients with lower-fat or fat-free ingredients.
• Leftover Turkey? Instead of turkey sandwiches, use the leftover turkey to make low-sodium soups with lots of fresh, chunky vegetables.
• Experiment with new recipes:  try substituting 2 egg whites for 1 whole egg; low fat plain yogurt or low fat sour cream for regular sour cream; skim or 1% milk for whole milk; frozen yogurt for ice cream; light butter for whole-fat butter; and low-fat or fat-free cream of mushroom soup for regular cream of mushroom soup (keep the sodium in check here as well).

Most importantly, enjoy your family and friends and have a Happy & Healthy Thanksgiving!!

© 2006 Lucho Crisalle, R.D., Exercise & Nutrition Works, Inc.

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