• Exposure to germs in an airplane
• Drinking contaminated water or ice  
• Eating foreign street vendor food 
• Overindulging in sweets, alcohol, breads, cheeses, etc. 
• Not drinking enough purified water 
• Lack of sleep
• Constipation  

Checklist of What to Bring on Your Vacation: 

• Probiotics - good bacteria to strengthen your immune system and help with daily elimination. Primal Defense Ultra by Garden of Life or Dr. Ohhira's Probiotics 12 plus 1 pill when arising and bedtime without food.

• Colloidal silver - one of the best antibacterial and antiviral remedies to have on hand, not just when traveling. Invision Silver 100 is one of my favorite brands that you can purchase on silver100.com or amazon.com. Put 3-5 drops under your tongue before boarding a plane, and each morning and night while vacationing. If you actually do get sick take recommended dose on bottle 4-5 times a day until you

  feel better. Can also be used topically on any cuts or scrapes. 

• Neosporin First Aid Ointment - put a little Neosporin ointment (antibacterial) around the edge of each nostril before flying in an airplane...learned that tip from a flight attendant.

• Digestive Enzymes - if you plan on eating a lot of foods that you don't normally eat or if you have a hard time digesting foods in general, take a digestive enzyme with each meal. Super Digestaway by Solaray on amazon.com or vitacost.com is a good enzyme.    
   
• Activated Charcoal Capsules - if you do get food poisoning take 1 to 2 capsules each day until you feel better. Any brand on vitacost.com or from your local health food store will do. Also drink a lot of water.            

• Moderation versus excess with regard to your diet. Vacations are times to enjoy food and drink but that doesn't mean that each day you need to eat Gelato, pastries, bread, cheese, and alcohol :))