Short answer

Our sources describe something specific about taking Calcium with Vitamin D3 with A, E and K2:

Vitamin D helps your body absorb calcium. If you take a thiazide diuretic, vitamin D could push blood calcium too high.

Calcium

What it is: The body's most abundant mineral; it builds bones and teeth and helps muscles, nerves and blood vessels work.

What the research says: Calcium supports bone health, especially when diet falls short. Vitamin D helps the body absorb it.

Cautions

• Upper limit from all sources: 2,500 mg a day for adults 19 to 50, and 2,000 mg from age 51.
• Some research links very high intakes to heart disease and prostate cancer risk.

Medicines to check

• Levothyroxine (thyroid medicine): keep doses apart
• Quinolone antibiotics: keep at least 2 hours apart
• Dolutegravir (HIV medicine) and lithium

In Holitro: Calcium Citrate (160 mg per capsule)

Source: NIH Office of Dietary Supplements: Calcium: Fact Sheet for Consumers (updated September 2023)

Vitamin D3 with A, E and K2

What it is: A combination of vitamin D3 with vitamins A, E and K2. Vitamin D helps the body absorb calcium and supports muscles, nerves and the immune system.

What the research says: Getting enough vitamin D and calcium helps protect against osteoporosis.

Cautions

• Adults shouldn't exceed 4,000 IU (100 mcg) of vitamin D a day from all sources unless a clinician advises more. Too much can cause nausea, weakness, confusion and kidney stones.
• Too much preformed vitamin A can cause headaches and blurred vision, and birth defects in pregnancy.
• High-dose vitamin E supplements may raise bleeding risk.

Medicines to check

• Warfarin: vitamin K and vitamin E both matter, and vitamin K intake should stay steady
• Statins, steroids, orlistat and thiazide diuretics (vitamin D notes)
• Vitamin A-based medicines such as acitretin

In Holitro: D Complex (5,000 IU per capsule)

Sources: NIH Office of Dietary Supplements: Vitamin D: Fact Sheet for Consumers (updated November 2022); NIH Office of Dietary Supplements: Vitamin A: Fact Sheet for Consumers (updated March 2025); NIH Office of Dietary Supplements: Vitamin E: Fact Sheet for Consumers (updated March 2021); NIH Office of Dietary Supplements: Vitamin K: Fact Sheet for Consumers (updated March 2021)

Check with your doctor or pharmacist, especially if you take medication.

Check your stack — free

Educational information only, not medical advice. This reflects general ingredient overlap, not a personalized safety review. Always check with your doctor or pharmacist before combining supplements, especially if you take medication, are pregnant or nursing, or manage a health condition. These statements have not been evaluated by the FDA.