Dr Oz has just highlighted vitamin C as one of the anti-agers that will "drop a decade from your face". I agree that vitamin C is a helpful anti-ager, but I strongly disagree with his guidance: "Look for products that contain between 3% and 10% of vitamin C and include the active ingredient ascorbic acid or L-ascorbic acid." First of all ascorbic acid is far from the best form of vitamin C to look out for. It is the least stable and most likely to irritate. There are much more impressive types of vitamin C, such as MAP (read up on vitamin C in all its forms). And the 3-10% range is just arbitrary. There are fantastic serums such as E'shee's that has 20% delivered over time so that it doesn't irritate, clever stabilizing ingredients, others with lower percentages of stable Cs that work really well, or those (such as Nutra-Lift or M.A.D) that have complex formulas of different Cs. Here's my new update on last May's Five Best vitamin C serums.

E’shee Serum Vitalizing C ($119 in the TIA shop). 20% vitamin C that is supposed to remain active in the skin for up to 48 hours. Junko promised that even my sensitive skin would like this C Serum and she was right. Here, liposomes stabilize the vitamin C and ensure that it is delivered more efficiently into the cells. Along with liposome vitamin C this serum gives us copper PCA, antioxidants mulberry and ginkgo biloba. Ginkgo biloba is an anti-inflammatory too. A high quality product that is deservedly a two-year winner in the Five Best vitamin C serum category. Read the full review

Snowberry Bright Defence Face Serum ($69 in the TIA shop) Snowberry describes Bright Defence as a serious, rapid-delivery anti-glycation and anti-free-radical formulation. Well, the second ingredient is l-ascorbic acid. Clearly, they are serious. Snowberry's solution is to use an enzyme in order to stabilize the ascorbic acid. But this enzyme is very clever. The enzyme enables a gradual release of the vitamin, thereby preventing any irritation. This serum is extremely mild and even sensitive skin types won't feel the slightest bit of a tingle. Moreover, this measured release of the vitamin prolongs its benefits for a longer period of time than ordinary vitamin C serums. There’s also kombuchka for glycation and a host of other good things. Read Nisha’s review

Nutra-Lift Maximun C Plus Growth Factors ($34 in the TIA shop) 20% vitamin C. The C to end all Cs! Never again will you be concerned that your vitamin C serum has the best, most stable and potent form of vitamin C. Nutra-Lift Maximum C Ultra Serum has it all - no less than five different forms of vitamin C. And that's not all, there's anti-inflammatory alpha lipoic acid, hydrating hyaluronic acid, antioxidant superoxide dismutase and even more vitamins in the form of D and E. Read Emily’s review

MAD’s Spot On Targeting Skin Brightening Serum ($38/0.50 oz in the TIA shop). A great dark spot fader at a very decent price. Although nianciamide (from the vitamin B family) features strongly, it is the vitamin Cs in this formula that merit a call out. Stay C-50 is sodium ascorbyl phosphate and, along with MAP (magnesium ascorbyl phosphate), it is recognized as a stable form of vitamin C.  A skin brightener, as well as antioxidant and UV protector, vitamin C is also here as a strong component of phyllanthus emblica. These Cs are given are given ample backup by very interesting actives in the whitening department. Read the full review

Mad Hippie Vitamin C Serum ($34 in the TIA shop). A popular product for its price to quality ratio, this has vitamin C as the second ingredient in a form that the company calls sodium ascorbyl phosphate (STAY-CR 50) which they claim is more stable and bioavailable than the traditional L-Ascorbic acid used by most companies. Also included are vitamin E, ferulic and hyaluronic acid, as well as the more unusual mineral-rich konjac root. Breakout-prone skins find this vitamin C serum gentle. Read Amy’s review

See all our FIVE BEST recommendations including Five Best for sagging skin and Five Best eye creams