Purpose:

The overall objective of this study is to learn more about the disease chronic pancreatitis and thus contribute to better treatments. The investigators will gain this by studying the effects of vitamin D in the body immune system and bones. The investigators will also study the uptake of vitamin D through the intestine compared with the amount of vitamin D obtained through exposure to UVB rays.

The investigators have set a series of questions which the investigators want to answer with this experiment:

Do patients with chronic pancreatitis have reduced absorption of vitamin D from the gut?

• Have the two treatment methods with vitamin D, UV radiation and tablets, the same success rate?
• Does the distribution of the white blood cells change when the vitamin D level increases and does it depend on whether the patient have UVB radiation or tablet with vitamin D?
• Will patients require reduced amounts of painkillers when vitamin D level increases?
• Does vitamin D have influence on blood sugar and thus the risk of diabetes or worsening of this?
• Could vitamin D affect the blood content of inflammation markers?
• Does the patient feel better when he takes vitamin D?
• Does bone strength increase when the patients receive grants of vitamin D?

Inclusion Criteria:

• Chronic pancreatitis
• Malabsorption
• Age min. 18 y.
• 25-hydroxyvitamin D less than 75 nmol/l
• Body mass index < 30
• Consent

Exclusion Criteria:

• Acute pancreatitis
• Cirrhosis
• Ionized calcium > 1.35 mmol/l
• Heart disease
• Former resection of gastro-intestinal tract.
• Pregnancy
• Pancreatic malignant disease
• History of skin cancer
• Other than skin cancer less then 5 y prior to inclusion in study
• Chronic kidney disease
• Type I diabetes
• Hemoglobin < 5.0 mmol/l
• Participating in other studies
• Not suitable for inclusion