Does Vitamin K Reduce Heart Disease Risk?
Author: Dr. Stephen Chaney
You are trying to live a heart healthy lifestyle, but it is so confusing. It seems like there are new heart healthy diets, foods, and nutrients each week. How can you possibly keep up?
Some of those “heart healthy” recommendations contradict each other. They can’t all be true. Which should you believe? I will answer that question in my new books “Slaying the Food Myths” and “Slaying the Supplement Myths.”
Today, however, I am going to add to your confusion by adding another nutrient, vitamin K, to your “heart healthy” list. When it comes to heart health, vitamin K is a neglected nutrient. Most people think it is just needed for blood clotting. It doesn’t have the recognition and glamor of omega-3s, antioxidants, and polyphenols for heart health. However, recent research suggests it may play a crucial role in protecting your heart. So, I will explain how vitamin K and heart disease are related.
Before, I go into today’s study, let me give you some background information on vitamin K metabolism and heart health.
Metabolism 101: Vitamin K and Heart Disease
Vitamin K is a coenzyme for enzymes that add carboxyl groups to proteins. Without going into a lot of boring detail, carboxylated proteins:
- Are more water soluble. That makes them more efficient at catalyzing metabolic reactions in our cells.
- Chelate calcium. That allows them to catalyze calcium-dependent reactions.
For this discussion there are 3 kinds of calcium-dependent reactions catalyzed by carboxylated proteins that are important to know:
- Reactions involved in blood clotting. Hence, vitamin K is essential for blood clotting.
- Reactions involved in depositing calcium in our bones. Hence, vitamin K is essential for bone formation.
- Reactions involved in removing calcium deposits from soft tissues. Hence, vitamin K is essential for keeping our arteries clear of calcium deposits.
If you think about those last two reactions, vitamin K deficiency is the worst of all possible worlds. Calcium in our bloodstream is less likely to be deposited in our bones and more likely to be deposited in our arteries. Vitamin K deficiency is bad for bone health and bad for heart health.
There is only one other factoid you need to know to understand the study I will discuss below. Because vitamin K is essential for the carboxylation of certain proteins, the uncarboxylated level of those proteins in the bloodstream can be used as an indirect assay for vitamin K deficiency. That is the assay that was used in this study.
How Was The Study Performed?
In this study (I.J. Riphagen et al, Nutrients, 9, 1334; doi: 10.3390/nu9121334, 2017 ) the investigators studied 4275 subjects enrolled in a clinical trial called PREVEND (Prevention of Renal and Vascular End-Stage Disease). The study population was recruited from the city of Groningen in the Netherlands.
In terms of study population characteristics, the average age was 53, the population was 46% male, 94% Caucasian, and 60% of the population already had renal disease at the time of enrollment (The significance of this will be discussed later).
Study participants were followed for 10 years. By then 279 had died, with 74 deaths attributable to heart disease. Here are the results of the study:
- 30% of the population was vitamin K deficient.
- Vitamin K deficiency was close to 50% for the elderly and for subjects with hypertension, diabetes, kidney disease, and cardiovascular disease.
- Vitamin K deficiency was significantly correlated with all-cause mortality and cardiovascular mortality.
The authors concluded: “Importantly, a low vitamin K status is not only a clinically relevant risk factor for adverse health outcomes, but it may be a modifiable risk factor. Given the availability of vitamin K supplements, vitamin K insufficiency seems an attractive target for preventative intervention. Future prospective clinical trials are needed to investigate whether correction of low vitamin K status can indeed improve health outcomes.”
Pros and Cons of This Study
Cons:
- This is an association study. It showed that vitamin K deficiency was associated with cardiovascular mortality, but it didn’t show that vitamin K deficiency caused cardiovascular mortality.
- Kidney disease reduces the efficiency of vitamin K-dependent carboxylation of proteins. This study relied on levels of uncarboxylated protein for determining vitamin K status, and 60% of the subjects had kidney disease. The study might have overestimated the prevalence of vitamin K deficiency.
- The population of the study were primarily Caucasian from one city in the Netherlands. It is not clear whether these findings would be equally true for other population groups.
Pros:
- This study is consistent with previous studies. Several other studies have reported a correlation between vitamin K deficiency and either arterial calcification or heart disease risk. At least one study has shown that vitamin K supplementation can reverse arterial calcification.
- The levels of vitamin K deficiency seen in this study are consistent with previous studies that have measured blood levels of vitamin K directly.
Vitamin K1 Versus K2: What Happens Naturally?
There are two forms of vitamin K, vitamin K1 and vitamin K2. Vitamin K1 is used for the blood clotting reactions. Vitamin K2 is used for the reactions involving bone formation and removal of calcium from soft tissues. That has led to a vigorous debate about whether vitamin K1 or K2 supplements are better. I won’t get into that debate, because the data aren’t conclusive yet. However, I will point out that there is a natural relationship between vitamin K1 and K2 that has existed for thousands of years.
Vitamin K1 is the primary dietary form of vitamin K. It is found in heart-healthy foods like green leafy vegetables; cruciferous vegetables like broccoli, Brussels sprouts and cabbage; and other healthy foods like carrots, blueberries, and asparagus. It is converted to vitamin K2 by our intestinal bacteria. Small amounts of vitamin K2 can also be found in less heart-healthy foods like cheeses, egg yolks, butter, chicken liver, and salami.
Simply put, if we eat healthy foods and have healthy gut bacteria, we get vitamin K1 from our diet, and our gut bacteria make all the vitamin K2 we need. This is a system that has worked well for humankind since the dawn of time. It’s only when we start messing up our diet and our gut bacteria that we need to start arguing about whether vitamin K1 or K2 supplements are better. It’s not nice to mess with Mother Nature.
The Bottom Line
A recent study in the Netherlands found that:
- 30% of the population was vitamin K deficient.
- Vitamin K deficiency was close to 50% for the elderly and for subjects with hypertension, diabetes, kidney disease, and cardiovascular disease.
- Vitamin K deficiency was significantly correlated with all-cause mortality and cardiovascular mortality.
The authors concluded: “…a low vitamin K status is not only a clinically relevant risk factor for adverse health outcomes, but it may be a modifiable risk factor. Given the availability of vitamin K supplements, vitamin K insufficiency seems an attractive target for preventative intervention.”
For more details about vitamin K and heart disease and a brief discussion of vitamin K1 and vitamin K2, read the article above.
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.