Vitamins D and K
Last time I discussed vitamins A, B and C. To carry on this week I will talk about vitamins D and K. Never heard of vitamin K? It has a very important role to play as you will see!
Vitamin D deficiency is incredibly common in the US, but many Americans mistakenly believe they aren’t at risk because they consume vitamin-D-fortified foods (such as milk).
There are very few foods that actually have therapeutic levels of vitamin D naturally and even fortified foods do not contain enough vitamin D to support your health needs.
Despite its name, vitamin D is not a regular vitamin. It’s actually a steroid hormone that you are designed to obtain primarily through sun exposure, not via your diet.
Researchers have pointed out that increasing levels of vitamin D3 among the general population could prevent chronic diseases that claim nearly one million lives throughout the world each year. Incidence of several types of cancer could also be slashed in half. One of the Nurses’ Health Studies showed that nurses who had the highest blood levels of 25-hydroxyvitamin D, averaging about 50 ng/ml, reduced their risk of developing breast cancer by as much as 50 percent. Similarly, a Canadian study done by Dr. Knight showed that women who reported having the most sun exposure as a teenager and young adult had almost a 70 percent reduced risk of developing breast cancer. Dr. Michael Holick states:
“Studies have shown that if you improve your vitamin D status, it reduces risk of colorectal cancer, prostate cancer, and a whole host of other deadly cancers by 30 to 50 percent. You’re correct. Cancer is a big deal. You need to realize that vitamin D is playing a very important role in helping to maintain cell growth and to help fight cancer when a cancer cell is developing in your body.”
Vitamin D also fights infections, including colds and the flu, as it regulates the expression of genes that influence your immune system to attack and destroy bacteria and viruses. Optimizing your vitamin D levels can help protect against:
- Cardiovascular disease. Vitamin D is very important for reducing hypertension, atherosclerotic heart disease, heart attack, and stroke. One study showed that vitamin D deficiency increased the risk of heart attack by 50 percent. What’s worse, if you have a heart attack and you’re vitamin D deficient, your risk of dying from that heart attack creeps up to nearly 100 percent!
- Autoimmune diseases. Vitamin D is a potent immune modulator, making it very important for the prevention of autoimmune diseases, like multiple sclerosis and inflammatory bowel disease.
- Infections, including influenza. It also helps you fight infections of all kinds. A study done in Japan, for example, showed that schoolchildren taking 1,200 units of vitamin D per day during winter reduced their risk of getting influenza A infection by about 40 percent. I believe it’s far more prudent, safer, less expensive, and most importantly, far more effective to optimize your vitamin D levels than to get vaccinated against the flu.
- DNA repair and metabolic processes. One of Dr. Holick’s studies showed that healthy volunteers taking 2,000 IUs of vitamin D per day for a few months up-regulated 291 different genes that control up to 80 different metabolic processes, from improving DNA repair to having effect on autoxidation (oxidation that occurs in the presence of oxygen and/or UV radiation, which has implications for aging and cancer, for example), boosting your immune system and many other biological processes.
Foods that provide vitamin D include:
- Fatty fish, like tuna, mackerel, and salmon.
- Beef liver.
- Egg yolks.
Vitamin K is an essential nutrient necessary for responding to injuries – it regulates normal blood clotting. In addition, by assisting the transport of calcium throughout the body,vitamin k may also be helpful for bone health: it may reduce bone loss, and decrease risk of bone fractures.
The Two Basic Types of Vitamin K
Vitamin K can be classified as either K1 or K2:
- Vitamin K1: Found in green vegetables, K1 goes directly to your liver and helps you maintain a healthy blood clotting system. (This is the kind of K that infants need to help prevent a serious bleeding disorder.) It is also vitamin K1 that keeps your own blood vessels from calcifying, and helps your bones retain calcium and develop the right crystalline structure.
- Vitamin K2: Bacteria produce this type of vitamin K. It is present in high quantities in your gut, but unfortunately is not absorbed from there and passes out in your stool. K2 goes straight to vessel walls, bones, and tissues other than your liver. It is present in fermented foods, particularly cheese and the Japanese food natto, which is by far the richest source of K2.
Vitamin K1 can convert to K2 in your body, but there are some problems with this, which I will discuss shortly. As a supplement, K1 is less expensive, which is why it’s the form used for neonates.
Making matters even more complex, there are several different forms of vitamin K2.
MK-8 and MK-9 come primarily from dairy products. MK-4 and MK-7 are the two most significant forms of K2, and act very differently in your body:
- MK-4 is a synthetic product, very similar to vitamin K1, and your body is capable of converting K1 into MK-4. However, MK-4 has a very short half-life of about one hour, making it a poor candidate as a dietary supplement. After reaching your intestines, it remains mostly in your liver, where it is useful in synthesizing blood-clotting factors.
- MK-7 is a newer agent with more practical applications because it stays in your body longer; its half-life is three days, meaning you have a much better chance of building up a consistent blood level, compared to MK-4 or K1. MK-7 is extracted from the Japanese fermented soy product called natto. You could actually get loads of MK-7 from consuming natto as it is relatively inexpensive, and is available in most Asian food markets. Few people, however, tolerate its smell and slimy texture.
So eat your leafy green and natto, get some sun and exercise and enjoy life!
Submitted by Tricia @ Nutrition by Tricia