This study will examine the effect of providing a structured program of daily nutritional supplements for a 8 weeks of intervention prior to Sleeve Gastrectomy bariatric surgery on bone mass density status and formation of critical nutritional deficiencies years after the surgery.

The present study hypothesis holds that providing an adequate nutritional supplements program prior to the surgery, combined with postoperative monitoring, will significantly lower the incidence of nutritional deficiencies in patients undergoing Sleeve Gastrectomy surgery, and will reduce complications arising from these pre-operative deficiencies.

The investigators plan to examine the effect of Vitamins supplementation prior to surgery on the status of postoperative deficiencies one year after the surgery. Evaluation of outcomes will be made based on the results of blood tests specified, and related tests of bone density.

Inclusion Criteria:

• Candidates for bariatric surgery
• BMI over 35 kg / m 2 accompanying morbidity or BMI over 40 kg / m 2,
• pre-operative evaluation standards with matching to carry sleeve gastrectomy surgery
• Vitamin D deficiency prior to surgery

Exclusion Criteria:

• patients who underwent bariatric surgery in the past
• psychiatric or mentally contraindication for the procedure
• lack of consent to follow-up
• endocrine problem that affects the weight that is unbalanced.
• Chronic kidney disease (CKD), nephrolithiasis
• Hypercalcaemia
• Hypercalciuria and renal stones nephrolithiasis
• Pregnancy, breastfeeding
• Using medications or disease condition known as affecting the status of calcium or bone metabolism 3 month prior to intervention
• Taking any nutritional supplements 2 weeks before the study.