The Co-Factor Most D3 Supplements Forget

By Vicki Ramirez, M.S.

The Familiar Question: Am I Actually Absorbing This?

Every winter, the same question turns up in practitioner offices: I’ve been taking my vitamin D faithfully — but am I actually getting it? It’s a fair question, and the answer often has less to do with the number on the label than with what happens after the capsule goes down.

Two things determine how much of a fat-soluble nutrient your body can take up, and a lot of D3 routines are missing one or both.

• The Two Gaps Most Routines Miss
• Gap One: D3 Needs a Partner
• Gap Two: Fat-Soluble Means Fat-Required
• Closing Both Gaps in One Capsule
• The Forms Inside the Capsule Matter Too
• Premier D3+K2: What Sets Us Apart
• Why Now: Summer Builds the Reserve You'll Draw on Later
• Building a Complete Musculoskeletal Foundation
• Frequently Asked Questions
• The Complete Equation, in One Capsule

The Two Gaps Most Routines Miss

Vitamin D3 and vitamin K2 are both fat-soluble. Their absorption involves the same digestive processes used to handle dietary fat, which is one reason formulation and meal composition can matter. * That one fact sits behind both ways a D3 program tends to fall short, and many routines run into at least one of them.

• Gap one: complementary K2. Vitamin D supports normal calcium absorption, while vitamin K supports K-dependent proteins involved in normal bone and calcium metabolism. * In other words, D3 helps make calcium available, while K2 supports how the body puts it to use.
• Gap two: lipid delivery. Because D3 and K2 are fat-soluble nutrients, incorporating them into a lipid-containing delivery system provides them in an environment consistent with their fat-soluble nature. This builds the fat component directly into the formulation rather than relying solely on what accompanies the dose. *

Many D3 supplements close one of these gaps, or neither. Patients either miss what K2 contributes to normal calcium metabolism, or they end up trying to time every dose around a fatty meal, which almost nobody keeps up. *

Gap One: D3 Needs a Partner

Vitamin D3 helps the body absorb and maintain the calcium needed for normal bone health. Vitamin K2 complements this activity by helping activate proteins that play important roles in bone mineralization and healthy calcium metabolism. *

Their roles are distinct but closely connected. Pairing D3 with K2 brings both nutrients into one formula, offering a more well-rounded approach to nutritional support for the skeletal system. *

Gap Two: Fat-Soluble Means Fat-Required

Fat-soluble vitamins ride the same route as the fat in your food. In the small intestine they get packaged into micelles, folded into chylomicrons, and carried out through the lymphatic system. With little or no fat present, absorption drops off. This isn’t a nice-to-have. It’s the basic chemistry of how these molecules get across the intestinal wall in the first place.

That’s also why the long-standing advice is to take D3 with a meal that has some fat in it. Studies comparing meal composition have generally found better uptake with a fat-containing meal than with fasting or a low-fat meal. A nutrient only helps you to the extent your body takes it in.*

Real life doesn’t cooperate, though. Most people take their supplements with coffee, or on an empty stomach, or halfway out the door. When that happens, the number on the label reads more like a suggestion than a dose.

Closing Both Gaps in One Capsule

This is the gap Premier Vitamin D3+K2 was built to close. Instead of leaving the fat up to whatever you ate that day, both vitamins are suspended in organic extra virgin olive oil inside a liquid-filled capsule. A lipid base is present in every single dose. *

So, you get all three parts in one capsule: D3, K2, and the lipid base they’re delivered in. No synthetic emulsifiers, no stand-in oils, and no unnecessary excipients. *

The olive oil is there on purpose. It’s a clean, well-studied fat that fits the way PRL formulates everything: put the right nutrients together and leave the unnecessary additives and synthetic excipients out.

The Forms Inside the Capsule Matter Too

Absorption is the headline. But the forms of the two vitamins are what make a well-absorbed dose worth having.

Vitashine®: Plant-Source Vitamin D3

Most supplemental D3 comes from lanolin, which is taken from sheep’s wool. Ours comes from Vitashine®, a lichen derived vitamin D3 registered with both the Vegan Society and the Vegetarian Society. It supplies cholecalciferol, the same form your skin makes in the sun. *

MK-7: A Long-Acting Form of K2

Vitamin K comes in a few forms: K1, plus the K2 group known as menaquinones. We use MK-7 (menaquinone-7), sourced from natto-fermented soybeans. What sets MK-7 apart from shorter-chain MK-4 is how long it stays in circulation. Its substantially longer half-life supports once-daily dosing.

A Clinically Relevant Dose

Each capsule gives you 5,000 IU (125 mcg) of Vitashine® D3 and 180 mcg of MK-7 K2. Meaningful amounts. The capsule itself is 100% plant-based, gluten-free, heavy-metal tested, and made without stearates or filler excipients. One daily or as directed by a qualified health practitioner. *

Premier D3+K2: What Sets Us Apart

Why Now: Summer Builds the Reserve You'll Draw on Later

There’s one more reason not to wait. Plenty of people assume summer sun keeps them covered, and for many it falls short. How much D3 your skin makes depends on your latitude, the short midday stretch when UVB is strong enough, sunscreen and clothing, your skin tone, and the slowdown that comes with age. Even during peak summer, many people don’t build much of a reserve.

It helps to think of summer a little differently. It isn’t a safe zone. It’s your chance to bank reserves before they start dropping. At higher latitudes — much of the northern U.S. — cutaneous vitamin D production falls to very little for several months in winter and your body draws on whatever it saved. Consistent daily intake of a well-absorbed D3+K2 supports maintaining vitamin D status year-round. *

Building a Complete Musculoskeletal Foundation

Premier Vitamin D3+K2 helps lay the groundwork for calcium metabolism, bone formation, and vascular health. When they want to round out musculoskeletal support, practitioners often pair it with a few companions: *

• Premier Calcium Magnesium Plus / Powder: bioavailable calcium and magnesium for bone mineralization, muscle function, and steady neuromuscular activity. *
• Premier Bone Health: focused support for healthy bone remodeling, skeletal integrity, and bone health over the long haul. *
• Premier Marine Collagen: collagen peptides for connective tissue strength, joint support, and structural resilience. *

Frequently Asked Questions

Do vitamin D3 and K2 need to be taken with fat?

Yes. Both are fat-soluble nutrients, absorbed along with dietary fat, so a lipid base matters. Premier Vitamin D3+K2 suspends both vitamins in organic extra virgin olive oil, so a lipid base is present in every capsule.

Does the way vitamin D3 is formulated affect absorption?

It can. Vitamin D3 is fat-soluble, so both the delivery vehicle and how the supplement is taken can influence absorption. An oil-based formulation provides a lipid carrier within the supplement itself, while a dry-powder D3 taken fasting does not provide that same lipid-containing environment. *

Should you take vitamin D3 and K2 together?

They’re built to work as a pair. D3 and K2 each contribute to bone health in different ways, making them a complementary combination. Pairing them offers broader nutritional support for maintaining healthy bones and normal mineral balance. *

What is the best form of vitamin K2?

MK-7 (menaquinone-7) is the form practitioners prefer because it remains in circulation substantially longer than shorter-chain MK-4 — long enough to support once-daily dosing. * Premier uses MK-7 from natto-fermented soybeans.

Is there a plant-based vitamin D3?

Yes. Many D3 supplements come from lanolin in sheep’s wool, but Premier uses Vitashine®, a D3 made from lichen so it’s vegetarian and vegan friendly. It’s the same active form of D3 your skin makes from sunlight, from a non-animal source.

Is summer sun enough on its own?

Not necessarily. Sun exposure can contribute to vitamin D production, but it doesn’t translate into the same amount for everyone. Think of summer as an opportunity to support vitamin D status before seasonal UVB exposure declines, rather than a guarantee that you’re covered. *

The Complete Equation, in One Capsule

Premier Vitamin D3+K2 closes both gaps in one go. You get plant-source Vitashine® D3 and long-acting MK-7 K2, carried in organic olive oil so the lipid base is already built in. The doses are meaningful, the capsule is 100% plant-based, and the purity and potency are verified. One capsule a day, and the whole equation comes together. *

Learn more at prlabs.com. Premier Research Labs, Nutrition That Really Works®

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Vicki Ramirez, M.S.

Vicki Ramirez, MS, is a Senior Sales Educator at Premier Research Labs with over 17 years of experience in the nutrition industry, including nine years with PRL. She holds a Master of Science in Kinesiology and Nutrition, bringing a strong academic understanding of human physiology and nutrition to her work. Vicki specializes in translating scientific research on ingredients and their mechanisms into clear, practical insights for healthcare practitioners and industry professionals. Her work focuses on bridging the gap between research and real-world understanding, making the science behind nutritional product formulations accessible and relevant. You did everything right. You take vitamin D. You even found one with K2. So why does absorption come up short? Usually, it comes down to an ingredient that rarely makes it onto the front of the label.