Vitamin K- in the lab and in life: 2013 Interns

This summer, (2013) the Vitamin K lab hosted 2 undergraduate students to learn about the nutrient vitamin K and the practical aspects of food analysis. (the Vitamin K Lab conducts food analysis of the vitamin for the USDA National Food Nutrient Database) Among other things, Maryanne and Monica focused on the role of vitamin K in human blood, where vitamin K is found, and physical food analysis. They were able to apply their lab knowledge about vitamin K in interviewing a father and son who are effected by a genetic condition that prohibits their blood from clotting properly. This page showcases a bit of what they learned in their own words.

See a video of one of the interns, Maryanne here

In the Lab: What is Vitamin K and why is it important?

Vitamin K is a fat soluble macronutrient that is largely stored in the liver and in fat tissues and plays a large role in blood coagulation and certain metabolic pathways that are important in bone health.There are three major types of Vitamin K. Vitamin K1 , also known as phylloquinone, is synthesized in the colon and can be found naturally in chloroplasts that are used during photosynthesis. For this reason, Vitamin K1  can be found in green leafy vegetables such as kale and spinach. Vitamin K2 , also known as menaquinones, has two principal forms that differ in side-chain length. Menaquinone- 4 is produced by human and animal tissue and is found mostly in meat and dairy products. Menaquinone-7 on the other hand is made by bacteria during fermentation and can be found in fermented cheeses and soybeans such as the traditional Japanese food, nattō. Vitamin K3, also referred to as menadiones, is an artificial compound that is used as a Vitamin K supplement. All forms of Vitamin K are important in maintaining healthy levels of coagulation and the calcification of bones.


How much Vitamin K is in that?

Food analysis is done in the Vitamin K lab in order to determine how much Vitamin K is present in common foods. This process involves the extraction, purification, and processing of foods.One begins by homogenizing the given sample of food so that the small portion being analyzed is representative of the food as a whole.  The next step is extraction, which includes breaking up the cell walls of the given food sample in order to expose vitamin k to the hexane that has been added to the solution. (Vitamin k is very soluble in hexane and quickly dissolves when the two come into contact.)  Solid-phase extraction (SPE) is the next process. The purpose if this is to separate Vitamin K related compounds that are dissolved in the liquid mixture from other, interfering compounds according to certain chemical properties. The end solution is a mixture that has fewer impurities and contains the nutrient, vitamin k, of interest.The final step is to run the sample through the high-performance liquid chromatography (HPLC) system.  This is done in order to separate the contents in the solution even further and to ultimately compute the amount of vitamin k in the sample. The use of a zinc column and mobile phase manipulate certain chemical properties of different compounds in the sample and result in a clear chromatography that can be analyzed. This process has been determined to be the most accurate way of measuring how much vitamin k is in a particular food. These results can be quantified and submitted to the USDA in order for the information to be available to the general public in a database. The USDA food database can be accessed by anyone and provides extensive information on the nutrient content of a wide range of foods. The results from the food analysis done in this lab can be seen in this database and are regularly used by dieticians when advising patients.Food analysis is important because it makes information about the contents of a wide range of foods readily available to the public. It is particularly important for people who need to be mindful of their nutrient intake. In the case of vitamin k, patients on warfarin, who are advised to limit their vitamin k consumption, must have this sort of information readily available in order to avoid complications with their treatment.

In Life: What role does vitamin K play in the body when blood does not clot properly?

Vitamin K’s largest role in the body is as a cofactor to an enzyme that carboxylates certain coagulating proteins in the body. Therefore, the Vitamin K levels in the body can have significant impacts on the blood’s ability to properly form clots. This is especially true for people who are on the drug warfarin. (Warfarin is a commonly prescribed medication for people whose blood clots too frequently. ) Warfarin works by blocking a critical step in the Vitamin K cycle in order to prevent the body from naturally producing Vitamin K. However, patients who consume Vitamin K through food sources may be significantly diminishing the effect of the drug. For this reason, patients who are on Warfarin are advised to limit their intake of foods rich in Vitamin K. Nevertheless, too little vitamin k consumption could lead to under coagulation and therefore nutritionists must find the optimal range of vitamin k intake for each patient. In order for nutritionists to properly advise someone on how much of certain foods they should have, they need to know how much Vitamin K there is in food. Below are excerpts from an interview with a Houston, TX father, Michael (names have been changed) and son (Stephen) who each have a genetic condition that prohibits their blood from clotting properly and currently take warfarin.

How did you learn you had a condition pertaining to blood clotting?
Michael: I had a DVT (Deep Vein Thrombosis) in my left leg. I experienced pain in my leg and decided to go have it looked at in the emergency room. They did an ultrasound, identified it and the next day, I went in for surgery and had it surgically removed.

What were the challenges you endured when starting medication?
Michael: Normally when you get a blood clot like that, they put you on a low does of Heparin and they start the warfarin right after. I didn’t have challenges with warfarin but the low dose Heparin was a challenge because I had to inject it intraperitoneal. I was on it for 2 weeks so I had to give myself injections twice a day of low molecular weight heparin.  I am currently on warfarin and my son was on it for about a year and then he quit taking it. He has come back on it recently and he’s taking a lower dose than I am.

Before warfarin were you very conscious about your diet in terms of health?
Michael: Yes, I was pretty conscious about my diet.

How did Vitamin K intake come up in conversations with your doctor?
Michael: Whenever I eat green, leafy vegetables, like broccoli, spinach, kale, the doctor said I needed to be careful because that can change your INR  (International normalized ratio), a laboratory test measure of blood coagulation, based on prothrombin time due to its interference with the drug.

Has your INR ever gone out of range?
(Note: When an INR is too low, there is an increased risk for developing an unwanted blood clot. When the INR is too high, there is an increased risk of unwanted bleeding or bruising, including dangerous internal bleeding)
Michael: Last week, my INR was a little out of range.

How did warfarin limit your physical activity growing up?
Stephen: I couldn’t play contact sports anymore since I was on blood thinners. I was on the football team but had to quit. I took up recreational soccer at least twice a week and they advised I shouldn’t be hitting the ball. However, I didn’t bruise or bleed easily. The one thing that did affect me was I felt more tired. When I came home from school, I would take a nap during the day, which felt unusual. As soon as I got to college, I decided I was going to stop taking it since I was so tired but I was aware of the risks. During the summer, I started working at an internship, I felt pain in my leg and I told the doctors to start me on warfarin again. There is definitely a correlation with the amount of exercise I do and physical activity as well as a correlation with the warfarin to my energy levels.