As far as I can find where Vitamin C is concerned, the controlling factor in how fast it's absorbed is not whether the food is a tablet or an orange, but how much Vitamin C has already been consumed.
The nearest I could find on the subject directly comparing the two is this article saying Orange juice and supplements are equally effective at Reducing Plasma Lipid Peroxidation in Healthy Adult Women http://www.jacn.org/content/22/6/519.full If you look they note that concentrations of Vitamin C in blood remained mostly the same amongst the 2 groups
Objective: To directly examine the contribution of vitamin C to the
antioxidant potential of fruits and vegetables, the antioxidant effect
of orange juice consumption (8 and 16 fl. oz.) was compared to the
antioxidant effect of supplemental vitamin C (dosage equivalent to
that supplied by 8 fl. oz. of orange juice).
Methods: Subjects (n = 11; 28.6 ± 2.1 years) received each treatment
in a 3 × 3 randomized crossover design, and each two-week treatment
was preceded by a two-week washout. During the entire trial, subjects
restricted fruit and vegetable consumption to ≤3 servings per day
except the vitamin C-rich foods (items containing >20 mg/serving),
which were restricted to ≤3 servings per week. A fasting blood sample
was collected at the end of each washout and each treatment period.
Results: Following washouts, plasma vitamin C and lipid peroxidation
(plasma TBARS) were similar by treatment group and averaged 25.4 ± 3.6
μmol/L and 3.82 ± 0.10 nmol/mL respectively. Plasma vitamin C
concentrations were similar following each treatment period, 37.9 ±
8.1, 45.8 ± 9.4, and 38.3 ± 12.4 μmol/L for the 8 and 16 fl. oz. orange juice treatments and the supplement treatment, respectively.
All intervention treatments reduced plasma TBARS as compared to
pretreatment values: −47% (p = 0.013), −40% (p = 0.083), and −46% (p =
0.015) for the 8 and 16 fl. oz. orange juice treatments and supplement treatment respectively.
Conclusions:These data indicate that the regular consumption of 8 fl.
oz. orange juice or supplemental vitamin C (∼70 mg/day) effectively
reduced a marker of lipid peroxidation in plasma.
Ofcourse this now relies upon how dependable the study conducted at the Department of Nutrition, Arizona State University East headed by Carol Johnston Phd is.
If you have a choice between a pill and food on a plate, I would advise the food however, as food gives other benefits, the actual act of digestion and satisfaction has other health benefits.