Cross-referencing clinical data
Collard
- Category
- Herb
Nothing to show here, and the reason why.
A pairing appears on this page only when a trial gave both ingredients together and measured the result. Collard has none that clears that bar.
No pairing for Collard has cleared review yet.
Stitching two separate single-ingredient studies into a pairing is the one thing this engine will not do. When a study of the combination itself holds up at source, it lands here with its citation.
No invented synergy. Where actives were studied on their own rather than together, the record shows each on its own evidence, never a combined effect no trial measured.
Research strength. Research strength says how much work stands behind the combination. It is never a product score.
Independent record. Every finding is cited to a named trial, dated, and never written by the brand.
20 pairings are live across the library today. Checked 20 July 2026.
Plays well withEstablished knowledge, not a trial
No study gave these as a pair, so they are not in the card above. But the reason they belong together is settled biochemistry, not a guess, so it is worth knowing.
Collard + Vitamin K2 MK7Established vitamin K biochemistry. Collard leaf is among the densest phylloquinone sources in the food supply.
Collard delivers vitamin K1 (phylloquinone), while MK-7 is a menaquinone. Both feed the same gamma-glutamyl carboxylase reaction that carboxylates glutamate residues on vitamin K-dependent proteins. They differ in half-life and tissue distribution rather than in the chemistry they enable. Anyone on a vitamin K antagonist should keep intake steady rather than variable, since it is the swing that matters.
Collard + Vitamin D3Established co-dependence of vitamin D and vitamin K in bone-mineral handling.
Vitamin D raises the production of osteocalcin and matrix Gla protein, and vitamin K is the cofactor that carboxylates them so they can bind calcium. Collard supplies the K1 side of that pairing along with dietary calcium. The relationship is well established at the biochemical level. Bone density outcomes from food-level intakes are a separate question and less settled.
Collard + LuteinEstablished carotenoid composition. Collard is one of the highest lutein foods measured.
Collard leaf carries lutein and zeaxanthin in the chloroplast, and these are the same xanthophylls that concentrate in the macula. Supplemental lutein and dietary lutein share the same micellar absorption route and the same transport proteins. Taking both simply raises the pool from two directions. Absorption from raw leaf is low without fat and without cooking or chopping to disrupt the chloroplast.
Collard + MCT OilEstablished fat-dependence of carotenoid and fat-soluble vitamin absorption.
Lutein, beta-carotene and phylloquinone from collard all need dietary lipid to form mixed micelles and cross the enterocyte. Eating the leaf with no fat leaves much of the carotenoid content unabsorbed. Long-chain fats do this more effectively than medium-chain ones because they drive chylomicron assembly, so olive or another long-chain oil is the closer match. The general principle holds for any added fat.
Collard + IodineEstablished goitrogen chemistry of Brassica glucosinolates.
Brassica vegetables including collard contain glucosinolates that release thiocyanate on hydrolysis, and thiocyanate competes with iodide at the sodium-iodide symporter. This matters only when iodine intake is already low, and cooking reduces the effect substantially. At normal iodine intakes and normal serving sizes it is not a practical concern. It is worth flagging for people eating very large amounts of raw cruciferous leaf.
Collard + SulforaphaneEstablished glucosinolate-to-isothiocyanate conversion in Brassica oleracea.
Collard is a cultivar of Brassica oleracea and carries glucosinolates including glucoraphanin, the direct precursor of sulforaphane. Myrosinase in the plant, released when the leaf is chopped or chewed, performs the hydrolysis. Boiling inactivates myrosinase, which is why cooking method changes the isothiocyanate yield more than the raw glucosinolate content does. Gut bacteria carry out some of the conversion when plant myrosinase is gone.
Collard + CalciumEstablished oxalate content differences across leafy greens.
Collard is a low-oxalate green compared with spinach, so the calcium it contains is not locked into insoluble calcium oxalate. Measured fractional calcium absorption from low-oxalate Brassica greens is high, in the range reported for milk. This is a real distinction between leafy greens that is often collapsed into one category. The amount per serving is still modest compared with a dairy or supplement dose.
Collard + Vitamin CEstablished ascorbate enhancement of non-heme iron uptake, with collard supplying both.
Collard contains both non-heme iron and ascorbate in the same leaf. Ascorbate reduces ferric to ferrous iron and keeps it soluble past the duodenum. Cooking degrades part of the ascorbate, so the internal pairing weakens with long boiling. Adding a separate vitamin C source at the meal restores the effect.
Collard + Beta-CaroteneEstablished carotenoid profile of dark leafy Brassica.
Collard carries beta-carotene alongside lutein in the same chloroplast membranes, and both compete for the same micellar and transport capacity. At high supplemental doses of one carotenoid the absorption of the others can fall, which is a known competition rather than a synergy. From food-level amounts in a mixed leaf this competition is not a practical problem. It becomes relevant when a single isolated carotenoid is dosed heavily.
Collard + Fish OilEstablished lipid-vehicle requirement for fat-soluble leaf nutrients.
Long-chain fats promote chylomicron formation, and phylloquinone and xanthophylls from collard ride out of the enterocyte in chylomicrons. Taking a leaf-derived carotenoid or a green-vegetable meal with an omega-3 oil raises the absorbed fraction relative to a fat-free meal. The mechanism is transport, not any interaction between the omega-3 and the carotenoid itself.
Who should be cautious
Nothing specific on file for Collard. Match the label to the daily amount above, and tell your doctor what you take.
Not medical advice. Show the label to your pharmacist.The forms it comes in.
Raw collard greensIntact tissue with myrosinase and glucosinolates in separate compartments, full ascorbate content, pigments still membrane-bound.Fits Salads and raw preparations where ascorbate retention and isothiocyanate generation on chewing are wanted.Trade-off Carotenoid and phylloquinone absorption from intact raw leaf is low without fat and mechanical disruption. Thiocyanate generation is highest in raw material.
Dried, milled greens powderDehydrated leaf, concentrated by weight, with enzyme activity and ascorbate largely lost to the drying step.Fits Green blends and capsules where a leaf-matrix contribution is wanted in a shelf-stable format.Trade-off Phylloquinone survives drying well and concentrates, which matters for anyone keeping vitamin K intake steady. Ascorbate and myrosinase do not survive. A gram of powder is not a serving of vegetable.
Glucosinolate-standardised leaf extractSolvent extract assayed for total glucosinolate or for a named glucosinolate such as glucoraphanin.Fits Formulas targeting the isothiocyanate pathway with a declarable figure per serving.Trade-off A glucosinolate figure is not an isothiocyanate figure unless active myrosinase is supplied or present. Extraction discards the carotenoid, mineral and vitamin K contributions of the whole leaf.
What the strongest studies found
The essence, in one line each.
- GC-MS profiling of Brassica oleracea identified the bioactive constituent classes present in the leaf material analysed.In vitro study. Ikuomola et al., 2025 (F1000Research). PMID 41098508 ↗
- Nutritional value, biochemical traits and growth of Brassica oleracea varied with red and blue light growing conditions, indicating that cultivation conditions shift leaf composition.In vitro study. Haghighi et al., 2025 (Plants). PMID 41375410 ↗
These are the studies our verdict leans on, chosen from the 2 we read for Collard. The full linked list is below.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.
