Cold sores, also known as fever blisters, are caused by one of two types of the herpes simplex virus, usually herpes simplex-1. Although up to 90 percent of people are infected with herpes simplex, only about 30 percent actually develop cold sores, according to University of Washington professor Lawrence Corey, M.D., in the 2008 edition of "Harrison's Principles of Internal Medicine." For these people, avoiding triggers such as illness, fatigue and even certain foods plays an important role in preventing attacks.
Nuts and Seeds
Nuts and seeds are rich an amino acid called arginine that promotes the growth of the herpes simplex virus in a test tube. At least one study in humans confirmed this effect: In the November-December 1984 issue of "General Dentistry," researcher Craig. S. Miller reported that high arginine intakes "invariably" preceded cold sore outbreaks in nine patients with the disease. Not all nuts and seeds are created equal, however. Macadamia nuts contain the most arginine and pistachio nuts the least, according to the U.S. Department of Agriculture's National Nutrient Database. Walnuts, hazelnuts, pine nuts, Brazil nuts, almonds, pecans, peanuts, cashews, pumpkin seeds, sunflower seeds and sesame seeds fall somewhere in between. Unfortunately, avoiding nuts and seeds also means avoiding foods like pesto and tahini that use them as ingredients. On the bright side, oils derived from nuts and seeds, such as peanut oil, sunflower oil and canola oil, are safe because they contain almost no arginine.
Acidic Foods
Acidic foods can cause mild tissue damage that precipitates cold sore outbreaks in some people. Fruits are often the worst culprits. Highly acidic fruits include limes, lemons, oranges, grapefruits, pineapples, cranberries and pomegranates. Medium acidic fruits include apples, pears, peaches, plums, berries and cherries. Fruit juices, preserves and puree are often worse than whole fruit because they are more concentrated. Although there are no highly acidic vegetables---even tomatoes fall into the medium category---canned versions can pose a problem because acids are added during processing to prolong shelf life. People with cold sores should also beware of foods such as pickles and salad dressing that rely on vinegar.
Hot Foods
Hot foods and beverages can burn the delicate tissues of the mouth, sometimes resulting in cold sores. Beverages are often the worst culprits. Touching the container or the surface of the food can provide an indirect assessment of temperature, as can inspecting for bubbles or steam. Dabbing a small amount of the food or beverage onto the back of the hand or wrist provides a more direct assessment. If a food seems safe, it helps to start with a small sip or bite. Excessively hot food and beverages can always be allowed to cool before consuming.
References
- United States Department of Agriculture: National Nutrient Database for Standard Reference
- "General Dentistry"; Use of lysine in Treating Recurrent Oral Herpes Simplex Infections; Craig S. Miller, D.D.S., M.A. et al.; November-December 1984
- "Harrison's Principles of Internal Medicine, 23rd Edition"; Anthony S. Fauci, M.D. et al.; 2008
- "Integrative Medicine"; David Rakel, M.D.; 2007
