In a July 2017 study, researchers at Surrey University concluded that, “vitamin D3 was twice as effective in raising levels of the vitamin in the body than its counterpart D2.”
Public Health England has previously reported that, “more than 1 in 5 people in the UK have low levels of vitamin D and has increased the recommended intake of the vitamin to 10 micrograms per day, throughout the year, for everyone in the general population aged 4 years and older.”
“Daily consumption of products containing vitamin D3 but not vitamin D2 will enable the population to meet this target helping to avoid the health implications such as osteoporosis, rickets and increased risk of cardio vascular disease which are associated with insufficient levels of vitamin D in the body.”
The researchers state, "our findings show that vitamin D3 is twice as effective as D2 in raising vitamin D levels in the body, which turns current thinking about the two types of vitamin D on its head. Those who consume D3 through fish, eggs or vitamin D3 containing supplements are twice as more likely to raise their vitamin D status than when consuming vitamin D2 rich foods such as mushrooms, vitamin D2 fortified bread or vitamin D2 containing supplements, helping to improve their long term health."