"High dose" refers to a large quantity or amount of something, usually a medication or a substance. It means taking or using more than the usual or recommended amount. Full definition
Now, with more studies indicating the danger of high doses of vitamin C, caution seems well founded. (thehealthyhomeeconomist.com)
Can be toxic It can be toxic if given in high doses of about 30 mg per pound of the dog. (lowchensaustralia.com)
Of course, since K2 is a fat soluble vitamin, it is important to check with a doctor before taking, especially at high doses of if pregnant or nursing. (wellnessmama.com)