January 17, 2019
Previous studies have established obesity as a predisposing risk factor for colorectal cancer (CRC), with as much as a 50-100% increase in risk in men and a 20-50% increase in women. With obesity rates steadily rising worldwide, it is increasingly important to understand the mechanisms by which obesity raises the risk of CRC and to design efficient and economic strategies to address this problem.
Previous studies have shown that high concentrations of vitamin D (VD) is associated with reduced risk of CRC. However, the current daily recommended allowance for vitamin D, established in 2010 and based on bone health, is not considered optimal for CRC prevention.
Associate Professor of Nutrition Zhenhua Liu, who operates the Nutrition and Cancer Prevention Laboratory, in collaboration with the labs of Associate Professor Richard J. Wood (Nutrition) and Distinguished Professor David J. McClements (Food Science), set out to investigate whether a high dose of VD could be utilized as an effective dietary strategy to prevent obesity-associated CRC, as well as what the optimal method for delivering such high dosages might be.
In the first study, which was performed on a genetically-engineered CRC animal model, Liu and colleagues demonstrated that the administration of a high dose of VD suppressed obesity-associated intestinal inflammation and tumorigenesis, and the co-administration of VD with sulforaphane, a bioactive component from broccoli sprout, further decreased the overall tumor incidence and size.
Vitamin D, as a fat-soluble vitamin, has low and variable absorption compared to other water-soluble vitamins. In the second study, Liu and colleagues set out to determine if a nanoemulsion-based delivery system - a method that has been increasingly utilized in the food industry to encapsulate, protect, and efficiently deliver fat-soluble dietary bioactive components - could be used as an effective approach to improve VD absorption. Their results show significant promise, suggesting that this technique might be a viable delivery method to improve VD absorption and thereby the blood VD status.
Together, these findings support the potential use of high doses of VD and the nanoemulsion delivery system as an effective cancer preventive strategy in obese people, though Liu and colleagues are quick to point out that this idea warrants further clinical studies.
Results of both studies recently appear online in the journal Molecular Nutrition and Food Research.
Liu’s work was supported in part by USDA grants (2014-67017-21762 and MAS00514, Z.L. and R.J.W., respectively) and a Dean's Incentive Grant, School of Public Health and Health Sciences.