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Diagnosing food intolerance


Related terms
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Related Terms
  • Adequate protein diet, Barry Sears, carbohydrate, diet, fat, low carbohydrate diet, protein.

  • The Zone diet is an unproven dietary regime, which has been popularized by Dr. Barry Sears through sales of his 1995 book, The Zone. Despite claims made in the book, there is little available research to support its overall benefit.
  • The Zone diet is a calorie-restricted diet that provides adequate protein, moderate levels of carbohydrates, essential fats and micronutrients spread through three meals and two snacks that approximately maintain the protein-to-carbohydrate ratio throughout the day.
  • Proponents believe that the Zone diet promotes optimal metabolic efficiency in the body by balancing the hormones insulin and glucagon. Insulin is responsible for converting, in the blood, incoming nutrients into cells. Glucagon regulates glucose in the liver. Overall, the Zone's food plan consists of a dietary intake of 40% carbohydrates, 30% protein and 30% fat.
  • Under this diet, recommended foods include fruits and vegetables (fresh or frozen), oatmeal (whole grain), protein powder (e.g. soybean isolate), chicken, turkey, lean beef, fish, low-fat cottage cheese, soy food, nuts (e.g. almonds, cashews, macademia, pistachios), extra virgin olive oil, natural sweeteners, such as fructose or stevia.

Theory / Evidence
  • Recent research seems to indicate that a low total caloric intake is associated with longer life expectancy. Based on animal studies, animals eating calorie-restricted diets may live 1.5 to 2 times as long as animals eating high-calorie diets. Theoretically, similar effects may occur in humans. The caloric restriction recommended by the Zone diet is below that of the average American and may be of benefit in weight loss and if maintained over decades in increasing life expectancy. On the other hand, athletes in training will likely suffer from decreased performance if restricted to the low calorie diet recommended by the Zone.
  • Despite proposed benefits, currently there are no high quality clinical trials available about the Zone diet or similar diets consisting of the recommended 40% carbohydrates, 30% fat, and 30% protein. The Zone diet is quite complex in terms of caloric restriction, ratio of carbohydrates/protein//fat, spacing of meals, preferential intake of certain fats, and avoidance or inclusion of a few specific foods.


Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Cheuvront SN. The zone diet and athletic performance. Sports Med. 1999;27(4):213-228.
  2. Natural Standard: The Authority on Integrative Medicine.
  3. Sears B. The Zone Diet and athletic performance. Sports Med. 2000;29(4):289-294.

  • Dermatophytosis (ringworm) is not always easy to diagnose in cats, especially because not all infected cats show the classic signs and symptoms of infection. Moreover, feline ringworm infections seldom have the characteristic ring-like shape of human ringworm infections. Therefore, simply looking at the lesion is not a reliable way to diagnose ringworm. Several testing methods may be used to diagnose ringworm. Very often, a veterinarian may use more than one method to confirm a diagnosis of ringworm.
  • Because cats can easily spread ringworm to other animals and humans, it is important to get an accurate diagnosis as quickly as possible if ringworm is suspected. Pet owners should keep cats with suspected ringworm separate from other animals and humans, and wash their hands after handing an animal that might have ringworm.
  • Wood's lamp: One of the simplest methods of diagnosing ringworm is using a Wood's lamp. This is a lamp that shines ultraviolet light (black light). Some types of fungi that cause ringworm will fluoresce (glow) bright green under a Wood's lamp. Only about half of all fungi that cause ringworm will fluoresce under a Wood's lamp, so veterinarians cannot rule out ringworm if a suspected lesion does not test positive by this method. However, because the Wood's lamp method is fast, easy, and inexpensive, it is often the first test used to determine if a suspected skin legion could be a ringworm infection.
  • Microscopic exam: A veterinarian may also pluck hairs or scrape skin cells from around a suspected lesion and inspect them under a microscope. The veterinarian will look for hyphae (threadlike fungal structures) or spores. A microscopic exam may also distinguish fungal infections from other skin parasites, such as mites. This is also a rapid and inexpensive testing method for ringworm and is accurate in about half of cases. However, spores are very small and easy to miss, so veterinarians will often perform additional tests.
  • Fungal culture: The most accurate way to diagnose ringworm is to perform a fungal culture. In this test, samples of skin or hair from a suspected lesion are placed on agar (a jellylike substance) containing nutrients that support fungal growth. This method not only confirms a fungal infection but can reveal the specific type of fungus.
  • Veterinarians may assign a pathogen score, or p- score, based on the number of fungal colonies growing on the contact plate. This is done to determine the severity of the infection and to guide treatment. P-scores are assigned as follows: 1 (<4 colonies), 2 (5-9 colonies), and 3 (the plate is completely covered with fungal growth).
  • Fungal colonies must be examined under a microscope to confirm diagnosis of ringworm. However, colonies can take up to a week or even longer to grow in a culture. Therefore, more rapid tests such as Wood's lamp and microscopic exams are usually performed first and confirmed with a fungal culture if necessary.
  • Biopsy: If the ringworm infection is deep in the skin or if other tests cannot reliably diagnose or rule out ringworm, a skin biopsy may be necessary. A sample of skin is taken from a suspected lesion, and a fungal culture may be performed. The biopsy can also be cut into thin sections and examined under a microscope. The veterinarian may apply a stain that makes the fungal hyphae or spores easier to see.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.