Vitamin K is one of those vitamins that we don’t pay much attention to, but we should. It is actually one of the fat soluble vitamins along with vitamins A, D, and E. Nutritionists often refer to the acronym ADEK when referring to these vitamins. I have a few other articles relating to the fat soluble vitamins (the case for eating liver, and vitamin K absorption).

Vitamin K has many functions in the human body; it mainly tells the calcium where to go. Thus it plays an integral part in bone health, cardiovascular health, hormone health, insulin sensitivity, energy, gene expression, and cancer prevention. Key to vitamin K is the role it plays in bone health, and bone health is paramount in cyclists.

Osteoporosis accounts for more hospital days than diabetes, heart attacks, and breast cancer. Osteoporosis / Osteopenia: a medical condition of decreased bone strength increasing the risk of broken bones.

Any avid cyclist in today’s world, weekend warrior or racer, knows of a fellow cyclist crashing and breaking bones in the process.  The unusual part is that sometimes it doesn’t take much of a crash to result in multiple broken bones.  I personally have seen a relatively mellow crash thinking to myself, that wasn’t too bad, only to find out that bones were broken in the fall.  A reason behind these bone-breaking accidents is the common case of osteoporosis.

While attending the Bob Roll Moab cycling camp, I recently heard a lecture from BMC cycling team doctor, Max Testa who said that he knew of a professional cycling team with 4 cases of osteoporosis and 8 cases of osteopenia! These are young healthy cyclists we are talking about!

Max and Bob also reflected on their earlier days with the 7-11 team with Andy Hampsten. They recounted that riders fell just as much then as they do today, but with the caveat there are a lot more broken bones in today’s professional peloton. In fact, Dr. Testa said that in 1988, the year Andy Hampsten won the Giro, he remembers about 3 to 4 bone fractures that year, compared with 2015, where there were over 12 to 15 on the BMC team alone. Surprisingly, this is not common knowledge to most of the cycling world.

Cyclists unfortunately are at the short end of the stick in being diagnosed with a bone disorder at some time in their athletic journey. One reason may be the fact that cycling is not a weight bearing sport.  Weight bearing sports include; jogging, hiking, tennis, and most team sports.  Cycling is a non-impact sport, which is great for various reasons, but osteoporosis not being one of them.

During one’s childhood, and into adolescence our bones become dense, flexible and strong reaching our maximum potential and remain so into our mid-twenties.  Once we hit that tipping point there is a slow, natural loss in bone density and flexibility over time.  Here is where it gets interesting if you are an avid cyclist.  Many studies show that the most important factor of bone health is how much weight-bearing exercises one does.  The forces, which are sustained in compressive activities, are what stimulate them to maintain their density. In general, activities that involves impacts with the earth, such as running and jumping, are the most effective way to improve bone health. Also, strong muscular contractions that tug at and slightly bend attached bones, such as a maximum effort dead lift, redoubles the effects of exercise.

Another kicker is the fact that the amount of alcohol & caffeine one drinks also is a contributing factor; the more you drink the thinner your bones become.  Hopefully there are not be too many alcoholics in the cycling world. But we all know how much coffee may be consumed by each cyclist. Moderation is the key.

While age, family history and small stature are unmodifiable risk factors for osteoporosis, there are many potentially modifiable risk factors. The food that you eat can affect your bones. Which brings up the point of sunlight and nutrition. Vitamin D and K2 are crucial for bones and for all of the roles performed by vitamin D. Vitamin D is responsible for enhancing intestinal absorption of calcium, iron, magnesium, phosphorus, and zinc. Ninety percent of our vitamin D must come from cholesterol that is activated by the sun. In addition, appropriate amounts of vitamin K2 are needed for proper bone metabolism. In fact, one study showed that vitamin K2 decreased the incidence of fractures by nearly 90%! Americans are deficient in many vitamins including vitamin D (70%), Vitamin K (35%). Even more, 45% of Americans are deficient in magnesium, and 38% are deficient in calcium.

Vitamin K2 is a specific form of vitamin K that is found in animal products and fermented foods, as opposed to vitamin K1 that’s found in green-leafy plant foods. There are multiple observational studies that suggest that higher vitamin K2 intakes is beneficial. Vitamin K2 is more effective at activating the systems that we’ve been talking about than vitamin K1. Unfortunately, humans are poor converters of vitamin K1 to K2. If you look at vitamin K2 intakes, people who are in the highest — depending on the study, are likely to have better bone mineralization, a lower risk of heart disease and blood vessel calcification and also a lower risk of multiple different types of cancer. Vitamin K, as a fat-soluble vitamin, requires proper lipid absorption for its own absorption. Liver disease and the like resulting in decreased bile salt synthesis leads to impaired vitamin K absorption and deficiency.

There are studies showing that vitamin K, in the elderly, where very high doses, caused a dramatic decrease in osteoporosis risk that was more effective than osteoporosis drugs; there were no reported adverse effects.

But how do we get vitamin K in the first place? If you look at what you’re going to get from food, the highest intakes of vitamin K2 tend to be topping out at 200mcg a day. Most people do not get that, but you could find that among people who are eating whole foods. In the Japanese trials they were using 45mg, a microgram is a thousandth of a gram. You’re talking about a magnitude one thousand times higher than what you could get from food.

Research has also shown that with high intensity sports; cycling, through your excessive sweating you are losing even more calcium, which just adds to the weakening of one’s bones.  The high intensity that comes with cycling results in a greater release in calcium in one’s bones, and even greater loss in calcium while sweating.  Unfortunately, studies have also shown that a routine use of calcium supplements alone is not effective when it comes to bone health and bone density.

A word of caution for female athletes, high amounts of exercise combined with caloric depletion can lead to accelerated osteopenia. This can create what’s called the female athletic triad, which can really decrease bone density. If you are taking a birth control medication, realize that this can deplete important nutrients such as the B vitamins and magnesium. Work with your doctor and / or nutritionist to correct these issues if necessary. A book by an orthopedic surgeon, The Bone Building Solution with Carolyn Demarco M.D. is an excellent resource.

If you look to other endurance sports such as runners & triathletes, they seem to benefit from the fact that running is an impact sport which by doing so offsets the bone losses caused by pure cycling.  This being said, it might be wise to consider adding some casual runs or even brisk walks to help the long term build up of bone density. Invest in a standing desk or workshop. It is common for pure cyclists to practice such activities in the off-season, but once the season starts these activities seem to drop off.  If one is looking to look at the big picture of long term health maybe you should look to practice such activities through out the season.  Light weight-bearing activities in the gym could go a long way in the long term if practiced continuously with your cycling, in theory.


Medical – ask your doctor to check your vitamin D levels and if you are really concerned, get a bone mineral density (BMD) screening test to check for osteoporosis. If possible, also have your other vitamins checked.

Nutrition – Eat whole nutrient dense foods and limit processed foods. Eat a variety of different foods to be sure that you get all of the nutrients together. Osteoporosis is prevented by all of nutrients working together. If you are exercising heavily, take into account that you may be deficient in certain nutrients and be sure to include them in your diet and / or take a supplement. Your body doesn’t absorb calcium well from foods that are high in oxalates, such as spinach and certain legumes. Consume alcohol and caffeine in moderation.

Exercise – perform a variety of high and low impact exercises and well as muscle strengthening exercises. Continue these activities throughout the year. Hire a personal trainer or someone knowledgeable in exercise and develop a plan that works for you. The national osteoporosis foundation recommends weight bearing exercises 30 minutes per day.


Food sources for magnesium: green vegetable, prickly pear juice, meats, spinach, quinoa, cheeses, nuts, fish, poultry, vegemite (Australia).

Food sources for vitamin K2: liver, fermented soy beans (natto), cheeses, egg yolks, butter, meats, organ meats, green vegetables, and oils.

Food sources for vitamin D: Sun exposure (UVB rays), cod liver oil, liver, salmon, sardines, dairy, cheese, and oils.

This article is meant for information only and is not intended to treat or diagnose any medical condition. For more information about performance and nutrition, follow Doc Edwards on his twitter DocEdwards5 or visit his homepage