Instalab ResearchTo understand the debate, it helps to know how vitamin D behaves once it enters the body. Both vitamin D2 (ergocalciferol, plant-derived) and D3 (cholecalciferol, typically animal-derived or synthesized) are biologically inert. After absorption, they travel to the liver, where enzymes convert them into 25(OH)D, the form doctors measure in blood tests. The kidneys then activate it into calcitriol, the hormone that does the real metabolic work.
Because vitamin D is fat-soluble, its absorption depends on dietary fats and the efficiency of the gut and liver. Drops, often dissolved in oil, might theoretically bypass some digestive hurdles by being better emulsified. Pills, in contrast, rely on the body’s ability to dissolve and mobilize fat molecules from a dry matrix. That’s the premise driving the “drops versus pills” debate, but does research back it up?
When researchers have put these two delivery systems head-to-head, the results have been surprisingly balanced. In one year-long study of immunodeficient adults who received either oil-based drops or tablets containing vitamin D3, both groups experienced nearly identical rises in serum 25(OH)D, from roughly 50 to about 85 nanomoles per liter after several months of consistent supplementation. Despite slightly different dosages, the biological response was indistinguishable. Drops and pills, it seems, delivered their sunshine with equal efficiency.
Other research, however, finds nuances. In older women, a randomized comparison of daily vitamin D2 drops and D3 pills found that D3 increased blood levels more effectively, even when both groups took equivalent doses. Yet here, the difference stemmed from chemistry, not delivery. D3 is simply more potent and more stable than D2. Across trials, D3 consistently raises and sustains 25(OH)D levels better, whether delivered as a capsule, drop, or even a fortified food.
A newer twist in the vitamin D story involves a compound called calcifediol, the very molecule measured in your bloodstream after the liver processes vitamin D3. Because calcifediol bypasses that metabolic step, it raises blood levels much more quickly. A 2024 systematic review found that calcifediol supplementation increased serum 25(OH)D concentrations faster and to higher levels than conventional vitamin D3, regardless of whether taken as a capsule or solution.
The same trend was observed in a large longitudinal study in young adults, where even those with obesity, a condition known to sequester vitamin D in fat tissue, showed robust improvements when supplemented with calcifediol. While calcifediol isn’t yet common in over-the-counter formulations, its efficiency underscores an important point: the body’s metabolic pathway, not the supplement’s physical form, often determines the outcome.
Even among people taking identical doses, the rise in vitamin D levels can vary dramatically. A large meta-analysis of European adults found that supplementation with 25 micrograms (1,000 IU) of vitamin D daily was enough to bring most people’s levels into the healthy range, but the response depended strongly on baseline status and body composition. People with lower starting levels saw a bigger boost; those with higher body fat or pre-existing liver issues often needed larger or longer doses.
A separate trial examining lifestyle and genetic factors found that adherence, sex, and seasonal timing explained about half of the variability in blood level increases, while BMI had only a modest effect. This means that the most powerful variable might not be the supplement’s format at all. It’s whether people actually take it consistently.
While drops and pills show near-equal performance, how often you take them may matter more. A six-month study comparing daily liquid drops to large monthly doses found that both regimens achieved normal vitamin D levels, though daily dosing provided steadier blood concentrations and better maintenance over time. High “stoss” or loading doses, common in clinical correction of severe deficiency, can work quickly but risk overshooting into potentially harmful ranges. Other work has even found a U-shaped curve in vitamin D outcomes, with both low and excessively high blood levels linked to increased mortality.
So, while liquid and solid forms perform comparably, the dosing pattern (small and steady versus occasional megadoses) may be more important for maintaining balance without risk.
There are, however, exceptions where drops may shine. For people with gastrointestinal malabsorption syndromes, pancreatic insufficiency, or liver disease, oil-based drops can be easier for the body to absorb. Even in liver-compromised patients, daily oily drops successfully raised 25(OH)D levels within eight weeks of supplementation. Drops also allow more flexible dosing and may improve adherence for those who struggle with swallowing tablets or who prefer adjusting their intake seasonally.
Still, for the average adult with normal digestion, tablets remain equally effective, easier to standardize, and often cheaper. The difference, practically speaking, may come down to personal preference and routine.
If there’s one unifying theme across this body of research, it’s that vitamin D supplementation, in nearly any form, works when done correctly. Whether you take it with breakfast in tablet form or place a few oil drops under your tongue, the key determinant is steady intake over time. The supplement’s vehicle, though chemically interesting, plays second fiddle to the consistency of the behavior.
And the payoff is substantial: even modest daily doses can shift most adults from deficiency to sufficiency within a few months. In Europe-wide data, 95% of participants achieved blood levels above the commonly accepted sufficiency threshold with just 1,000 IU daily over a few months. The body’s response is not instantaneous, since vitamin D stores build gradually, but the long-term benefits are well supported.
If you have no absorption issues, either form will serve you well. Focus instead on taking the right dose for your needs (often 1,000–2,000 IU daily for maintenance, or higher if directed by a clinician) and maintaining consistency across seasons. If you have digestive or liver problems, or simply prefer a liquid, oil-based drops might offer a slight edge. But the real difference lies in adherence. The best supplement is the one you’ll actually remember to take.
