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Vitamin C

Vitamin C serves as a cofactor in enzyme function and as an antioxidant. It protects tissues from oxidative stress and plays an important role in preventing chronic diseases. Vitamin C helps form the fibrous connective tissues known as collagen for bone and teeth formation. The food sources include broccoli, strawberries, kiwi, and bell peppers [23].

Due to limited consumption from bariatric surgery, patients may need to consider supplementation.

Vitamin D

Vitamin D is a fat-soluble prohormone synthesized by the skin when it is exposed to ultraviolet B (UVB) radiation. Vitamin D comes in two forms—D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D2 is synthesized for use in dietary supplements and fortified foods. Vitamin D3 is synthesized as a result of skin exposure to the sun and also occurs naturally in some animal foods—egg yolks, fatty fish, cod liver oil [7, pp. 108-111].

Medicine has regarded these two vitamers of vitamin D as equivalent and interchangeable according to the American Journal of Clinical Nutrition but this conclusion is outdated and bariatric health professionals need to reconsider their recommendations accordingly [7, pp. 108-111]. Previously, vitamins D, D2, and D3 were considered equivalent based on studies that evaluated their ability to prevent rickets in children. Today, vitamin D status needs to be assessed on calcidiol or 25-hydroxyvitamin D metabolite activity. According to the comparative study of vitamin D2 and vitamin D3 supplementation, vitamin D3 was considered more potent and less toxic at higher doses than vitamin D2.

Both D2 and D3 are biologically inert until they undergo two hydrox- ylation reactions. The first is in the liver to form 25-hydroxyvitamin D (25[OH]D). It is then further hydroxylated in the kidney to 1,25-dihy- droxyvitamin D (1,25[OH]2 D) [7, pp. 108-111].

Vitamin D promotes bone mineralization, neurological and immune function, and influences cell growth and repair. Occurrence of malabsorption in chronic liver disease, pancreatic insufficiency, celiac/gluten sensitivity, and Crohn’s disease has been reported [24]. Evaluation of vitamin D levels in bariatric patients needs to be done to assess prevalence and need.

Deficiency symptoms in adults present as bone pain, muscle weakness, and fatigue. Individuals, who have limited sun exposure and rely on vitamin D2 supplementation, may not achieve desirable serum levels because of reduced stability and bioavailability of D2 [25].

Adiposity also impacts vitamin D status. People with larger amounts of adipose tissue increase their calcidiol levels only half as much as people with lower fat mass when given similar doses of vitamin D. Adipocytes sequester vitamin D and the relevance of this relationship needs further exploration [26].

To reach a healthy calcidiol level, the IOM recommends a daily vitamin D intake of 600 IU until age 70, then 800 IU for older Americans. The optimal dose of vitamin D remains a research question. A number of studies indicate 800 IU/day provides better benefit than 400 IU/day. Some studies have found that 25(OH)D can be increased with daily, weekly, or monthly supplementation—1,500 IU/ day or 10,500 IU weekly or 45,000 IU monthly [27]. Other studies recommend daily supplementation to be more effective [28].

Moderate sunshine exposure may be the best method to obtain vitamin D with the exposure of arms, legs, and face 5-15 minutes, two to three times daily between 10 am and 3 pm, April to October [29]. As Chan et al. indicate, vitamin D status postbariatric surgery is critical for assessment and repletion [30].

Food sources of vitamin D3 are fish liver oil (cod liver oil), egg yolks, butter, and grass-fed beef liver. Homogenized milk and most cereals are “fortified” with synthetic vitamin D.

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