Intestinal alkaline phosphatase (IAP) is a membrane-bound enzyme found in the intestines, which function is to take away phosphate groups from a large number of molecules. For example, the absorption of the B6 vitamins pyridoxal phosphate and pyridoxamine phosphate is dependent on their dephosphorylation by intestinal alkaline phosphatase. IAP is also responsible for removing the phosphate from lipopolysaccharide (LPS), an endotoxin found on gram-negative bacteria that normally induces the fever response. A properly functioning intestinal alkaline phosphatase is important to prevent an immune response against the (good) gram-negative bacteria living in our gut.

Crohn’s disease and colitis are believed to be caused by an abnormal immune response to gram-negative bacteria in the intestine, a feature which may be shared with rosacea. Both Crohn’s disease and colitis are associated with reduced levels of intestinal alkaline phosphatase and the pathology of these diseases have been suggested to be triggered by LPS. Taking oral antibiotics for rosacea is believed to help eradicate these bacteria, resulting in a decreased immune response and subsequent improvement in rosacea symptoms.

Many people with rosacea are advised to modify their diet as many dietary triggers exist for rosacea. However, these dietary trigger factors vary from individual to individual and thus far no clinical evidence for a so-called anti-rosacea diet exists. The author of the paper further suggests that the typical Western diet (which is high in processed foods and low in fresh fruits and vegetables) results in a more acidic environment in the intestines. As its name implies, intestinal alkaline phosphatase works best in a more alkaline (or basic) environment with a pH in the range of 9-10.

Foods that lower IAP activity
IAP enzyme is inhibited by phytates, a substance found in grains and legumes. The only way to properly get rid of phytates is to cook grains and legumes well. In addition, the amino acid phenylalanine (found in some artificial sweeteners) also inhibits intestinal alkaline phosphatase.

Foods that stimulate IAP activity
Here are a number of foods that increase intestinal alkaline phosphatase activity:

• Short chain fatty acids such as butyrate, derived from butter or from fermentation of dietary fiber in the gut
• Fish oils (Omega 3, 6 and 9, either as a supplement or from fresh sea food)
• Dietary Zinc (found in oysters or as a supplement)
• Vitamin A (as found in carrots, sweet potatoes, pumpkins)

It is further suggested to increase the gut’s alkalinity by eating a variety of fresh fruits and vegetables and stay away from hard and processed cheeses and processed meat. Finally, adding probiotics to your diet may further decrease rosacea symptoms by the colonization of the g.i. tract with beneficial gram-positive bacteria while reducing the growth of LPS containing gram-negative bacteria.

Intestinal alkaline phosphatase is also stimulated by estrogen and inhibited by progesterone. For this reason, rosacea symptoms could appear during pregnancy and in women who use birth control pills.

Whitehead J. (2009) Intestinal alkaline phosphatase: The molecular link between rosacea and gastrointestinal disease? Med Hypotheses [Epub ahead of print Jun 30] doi:10.1016/j.mehy.2009.02.049