Can Vitamin D Supplements Thin Your Blood?

Vitamin D deficiency affects about 1 billion people worldwide, according to StatPearls. Many folks turn to vitamin D supplements to help them make up for gaps in their diet. And some people take cod liver oil or cod liver oil capsules as an alternative to conventional supplement pills.

Both conventional vitamin D supplements and cod liver oil may affect your blood’s ability to clot. Read on to learn what the research says and what other considerations to keep in mind.

How Vitamin D Affects Blood

Vitamin D is a fat-soluble nutrient that helps your body absorb calcium, making it essential for bone growth and health, according to the National Institutes of Health (NIH) Office of Dietary Supplements.

Your body can make vitamin D naturally through your skin’s exposure to the ultraviolet rays of the sun. You can also get vitamin D from fortified milk and oily fish such as salmon. Vitamin D supplements can help make up for gaps in your diet, as long as you get your doctor’s advice on how to use them properly.

Vitamin D is not necessarily considered a blood thinner (also called an anticoagulant), but research suggests that it does have anticoagulant properties.

Based on past studies, vitamin D appears to inhibit blood clotting (coagulation) by regulating two proteins (called thrombomodulin and tissue factor) that play key roles in blood clotting, according to a research review. Vitamin D may also help protect against inflammation, a significant factor in blood clotting.

Plus, a deficiency in vitamin D has been linked with a greater risk of thromboembolism, which is when a dislodged blood clot blocks a blood vessel, according to a book about the vitamin. A meta-analysis also supports a link between vitamin D deficiency and venous thromboembolism.

That said, experts still need to do more large-scale studies to determine vitamin D’s effect on coagulation and exactly how it works.

In general, the NIH Office of Dietary Supplements recommends 15 micrograms (mcg) of vitamin D daily for adults ages 19 to 70 and 20 mcg for adults older than 70.

If you’re concerned about vitamin D supplements and blood thinning, talk with a doctor. They can recommend the right amounts for you based on lab tests and a personal evaluation.

How Cod Liver Oil Supplements Affect Blood

Cod liver oil, either in natural form or in capsule supplements, is made from the oil of codfish. It is rich in vitamin D and consists mostly of omega-3 fatty acids, according to the National Library of Medicine.

Cod liver oil may support your brain, heart, and joint health, according to Cleveland Clinic. Fish oils like cod liver oil may also help you manage certain conditions, such as high blood pressure or high cholesterol, according to Mayo Clinic.

But cod liver oil can affect anticoagulant drugs. This may interfere with blood clotting and increase your risk of bleeding if you take the supplement with blood-thinning medications.

Research suggests that omega-3s, such as those found in cod liver oil, inhibit the buildup of platelets in your blood. And platelets play a critical role in blood clotting. According to the University of Rochester Medical Center, omega-3s may help prevent the formation of blood clots.

Yet people who took omega-3 polyunsaturated fatty acids did not experience an increased risk of bleeding, according to a review and meta-analysis.

More research needs to be done on this topic to determine how and whether cod liver oil and omega-3s affect your blood.

In the meantime, your best bet is to talk with your doctor about how much cod liver oil, if any, is right for you to take.

Considerations

If you are deficient in vitamin D, you can work with your doctor to figure out which type of supplements are best for you.

Be sure to let your doctor know if you’re taking any blood-thinning medications, too. That can affect which vitamin D supplements they recommend and how much they advise you to take.

Taking too much vitamin D, especially if you don’t have a deficiency, can cause too much calcium to build up in your blood, according to the United Kingdom’s National Health Service. This can weaken your bones and hurt your kidneys and heart.

It’s also important to remember that, especially in the summer months, most people get enough vitamin D simply through exposure to sunlight.

But because the sun can harm your skin, it’s important to use sunscreen when you’re outdoors and to take breaks in the shade. In fact, according to MedlinePlus, 10 to 15 minutes of sunlight three times per week is generally enough for your body to make the vitamin D it needs.

You can also focus on getting vitamin D through your diet. According to Harvard University, foods that have vitamin D include:

• Beef liver
• Cereals fortified with vitamin D
• Dairy and plant milks fortified with vitamin D
• Egg yolks
• Fish like salmon, sardines, swordfish, and tuna
• Orange juice fortified with vitamin D