A 9 - year - old girl who has kidney disease, heart problems or elevated blood calcium levels should not take supplemental vitamin D - 3. (healthyeating.sfgate.com)
In humans the effect is uncertain, as the impact of supplemental vitamin C varies widely by study. (perfecthealthdiet.com)
One other difference is that guinea pigs need supplemental vitamin C in their diets. (petbusiness.com)