Gear up, flaps down and get ready for take-off. Planning your outdoor adventures with a focus on nutrition is particularly challenging when air travel is involved. International flights cross time zones and stopovers in other cultures play havoc with our sleep/wake cycle and dietary patterns. Proper fueling and adequate hydration during travel can play a significant role in keeping you healthy and fit for adventure.

The most critical nutrition issues for air travel are adequate hydration and fuel that is easily digested. Hydration challenges increase with alcohol or excessive caffeine intake. Dehydration and hours of sitting negatively impact digestion and elimination of nutrients. Dry air in the airplane cabin increases fluid needs, so we recommend eight ounces of water per hour in flight.

Stopovers and changing planes in foreign countries can add irregular and exotic changes to your usual eating patterns. Tempting as local foods may seem in these situations, it is better to err on the side of caution and rely upon snacks from home during travel. As with all wilderness and foreign travel, be sure water is safe to drink to avoid serious food or waterborne illnesses.

Prior to or between flights you may spend hours of time in airport lines – check-in, security, customs, and boarding. Long layovers may involve wandering about airports, perhaps toting a carry-on bag or two. Unless your mouth feels dry or your stomach rumbles you are not likely to think about fuel and fluid for this particular part of your journey. Begin your journey well-hydrated and fueled with the recommendations below.

• Travel snack ideas are easy for the seasoned back-country adventurer since many of our favorite trail snacks can be easily taken into airports and on airplanes – nuts, seeds, dried (and some fresh) fruits, PBJ sandwiches, buffalo jerky, granola bars or other types of protein bars.
• Stick to your usual healthier eating habits which include eating an assortment of colorful veggies and fruit, whole grains, beans, nuts and seeds, along with some lean meat, fish or vegetarian protein sources, and pasteurized dairy foods when traveling. Keep portion sizes reasonable and if you save perishable leftovers to nosh later, make sure they are eaten within two hours.
• Carry on perishable foods such as cut up veggies, yogurt, hummus, string cheese, veggie wrap sandwiches and one liter of water. Nut butters and hummus are treated like "creams and lotions" and must be limited to three-ounce containers and included in your quart size bag of "liquids." Consume the liter of water from the time you arrive at the airport until the security check point. Purchase additional water and beverages or bring an empty water bottle and fill it yourself after clearing airport security.

Many countries limit foods that may be carried through customs, particularly produce. Below are websites containing detailed information about foreign and U.S. restrictions related to food.

• A listing of foreign embassies and consulates in the U.S. is available on the Department of State's website
• For information on U.S. customs regulations and procedures, read, "Know Before You Go"
• For further information, read on the same website.

Fortunately, there are currently many more options for nutritious fare in domestic airports. Salads, wraps with whole grain tortillas, vegetarian pizzas, and soups featuring legumes such as white or black beans, split peas or lentils, are some of the healthier options. Several Mediterranean cafes and restaurants feature falafel, hummus, grilled fish and chicken entrees, and colorful salads bursting with fresh veggies.

Here are some highlights from my "healthier airport/airplane food options" research for domestic airports:

• "Fresh Mexican" restaurants including Qdoba, Chipolte Grill, and Chicago O'Hare's Torta stand features Rick Bayless Mexican dishes. Lighter fare with grilled fish, chicken and lean meats, whole beans, assorted fresh salsas and corn or whole wheat tortillas boost the dietary fiber.
• Oatmeal is an option at restaurants such as Starbucks, Au Bon Pain and Jamba Juice.
• "Real Food" in Houston, "360 Gourmet" in Las Vegas and Dallas/Fort Worth, "Nature's Table Bistro" in Orlando, and Hamachi Sushi in Newark all received kudos for their healthier vegetarian options in a recent survey conducted by the Physicians Committee for Responsible Medicine.
• Alaska Airlines got a thumbs-up from several friends who enjoy their fresh fruit and cheese plate or their vegan and gluten-free choices including dried apricots and Endangered Species dark chocolate.
• Standard fast food restaurants now include salads, vegetarian entrees or soups, yogurt and fresh fruit alongside the usual high-fat, greasy offerings.

If your travel plans include a significant layover at an airport you can go online ahead of time and see what is available for healthier options. Remember...good nutrition can fuel your adventure long before you arrive.

Here's a WebMD article with some good tips too!