Comparative analysis of vitamin D content in sardines canned in olive oil and water
Kalajian, Tyler Arek
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Vitamin D is a fat-soluble hormone primarily responsible in maintaining plasma calcium and phosphorus homeostasis in humans. Vitamin D insufficiency and deficiency is a global health issue. Very few foods naturally contain vitamin D; a major source is oily fish such as salmon. Several studies have analyzed vitamin D content in various fish, however studies concerning canned fish are lacking. In particular, this study was interested in evaluating the vitamin D content in canned sardines in not only the whole fish but also in the olive oil or water it was canned in. It was hypothesized that the vitamin D content in sardines canned in water would be greater than sardines canned in olive oil due to the fat-soluble nature of vitamin D to be more easily extracted into olive oil than water. Sardines (~100g) canned in olive oil had a slightly greater vitamin D content than the sardines in water (2,555.6±234.2 and 1,993.7±2,411.3 IUs (p<0.05) respectively). An evaluation of the vitamin D3 content in the olive oil and water used to can the sardines revealed 701.4±471.1 and 149.1±42.2 IUs in the total olive oil and water respectively recovered from the cans. It was determined that of the total vitamin D content in the can (sardines in olive oil or water) 20.9%±12.8% of vitamin D3 is found in the olive oil compared to only 14.2%±10.4% (p<0.05) vitamin D3 found in water. These results support the concept that sardines packed in olive oil may have less vitamin D3 than similar sardines packed in water. The analysis of the sardines revealed that they had more than 13 times the amount of vitamin D3 than that is reported in the USDA table of nutritional facts for canned sardines. This could be because the sardines were caught in the summer months when they are more likely to be consuming food containing vitamin D3 as a result of reduced synthesis of vitamin D3 in zooplankton and other lower life forms that the sardines consume. An alternative explanation for this increase in vitamin D3 content is the process of canning the sardines. Vital Choice, the supplier of the sardines, immediately ices the fish upon retrieval from the ocean (to ensure freshness) and then are canned in less than 5 hours after being caught. This process of freshness preservation could explain why the vitamin D content was so high; possibly an accurate representation of the original vitamin D content in the sardines.