Preservatives linked to high blood pressure and heart disease in new study

Any vitamin will cause diseases in high enough doses, the problem is that for most of them, like also for most other essential nutrients, the safe upper limits of daily intake are known with much less certainty than the lower limits.

I browsed quickly through TFA, but it did not seem possible to estimate which are the vitamin C doses that might be harmful, which would have been the really useful and interesting information.

There is the additional circumstance that vitamin C added as a preservative, like also sugar added to some juice, is present as a water solution, so it will be absorbed quickly and efficiently immediately after ingestion. Both vitamin C and sugar that are incorporated in some fruits or vegetables will be released more slowly and possibly incompletely from them.

Thus a smaller dose of preservative vitamin C might be equivalent with a greater dose of vitamin C ingested as bell peppers, kiwi fruits, blueberries etc., which means that the safe limits for vitamin C added as a preservative (or taken as powder or pills) might need to be lower than when it is a natural component of food.