Vitamin K and Bone Supplements
As owners, we want to make sure our horses have strong and healthy bones throughout their lives. A hot new area of supplements includes products that are meant to increase bone mineralization and strength.
Are these products you should consider?
Role and Function of Vitamin K
The majority of supplements designed to increase bone mineralization and strength contain vitamin K. Let's start by talking about the function of this vitamin so we can make accurate choices as consumers on how we feed our horses.
Vitamin K is a fat-soluble vitamin stored in the liver of horses. It has been known to be connected to the blood system in humans and only recently has been shown to play a role in other systems including bones. It is thought to increase bone production, reduce bone resorption, and help with the formation of the bone mineral matrix.
Most of the push for vitamin K comes from results seen in humans. However, horses and humans appear to not have the same source, absorption, and distribution of this vitamin making it hard to translate the research to horses. Additionally, human studies looking at the effect of dietary Vitamin K on bone health show conflicting results.
What are the different types of Vitamin K?
There are 3 different types of Vitamin K that can be present and it is important to know the difference. They are:
Vitamin K1 (phylloquinone): Naturally occurring; poor absorption in the horse. K1 is bound to the chloroplast membrane of leafy green vegetables.
Vitamin K2 (menaquinone): Naturally occurring, produced by bacteria in the hindgut (cecum). There are 15 different menaquinones and K2- Menaquinone-4 is implicated in bone health.
Vitamin K3 (menadione): Synthetic vitamin K, not naturally occurring. It can be found in some commercial vitamin and mineral premixes and is added to feeds and supplements. However, toxicity has been reported.
How much Vitamin K does my horse need every day?
The Recommended Daily Allowance (RDA) for Vitamin K is currently not established in horses. That said, here is what we do know:
Horses are not known to have Vitamin K deficiencies due to diet.
Horses produce Vitamin K2 in the cecum (hindgut) via the microbes and this is suspected to meet the daily requirements.
Fresh grass is the main source of Vitamin K and the concentration is lower in cereal feeds.
A neonatal foal is more likely to experience a deficiency.
Blood coagulation issues and osteoporosis in humans might be related to a deficiency in Vitamin K and could translate to horses.
Overall, findings suggest a possible association between inadequate Vitamin K intake and the development of bone diseases in young horses. This observation warrants further investigation as the consequences are not fully understood.
Consumer Thoughts on Bone Supplements
Based on a survey of approximately 10,000 horse owners in the USA, 63% do not know what bone supplements do. 27% also indicated that they do not use bone supplements due to concerns about risk, price, and safety.
Out of everyone surveyed, only 8% of the respondents had used a bone supplement.
Based on these findings, general education to owners about active ingredients, options, and safety will be very important to prioritize as we add to the knowledge of Vitamin K and bone supplements.
Should you add a Vitamin K-containing supplement?
So back to the original question, should we use vitamin K and bone supplements in our horses?
In humans, there is currently insufficient data to make any recommendation. The only recommendation given is that it should only be used if there is a known deficiency or bone coagulation problems. Given there is less information on our horses, the same through process should carry through.
What can you be doing?
One of the best things you can do for your horses’ bone health is to ensure that the hay and concentrates you give provide the RDA for calcium, phosphorus, and magnesium. The RDA for these depends on your horses’ lifestage, training program, and weight.
Additionally, checking their calcium/phosphorus ratio is very important. Especially if you have a horse 2 yrs of age or under. You should pay particular attention to this ratio when alfalfa makes up a significant percent of the diet (pellets, long stem hay, and/or cubes). The amount of alfalfa that is suitable really depends on the horse.
Proper exercise is also known to help build bone density. Avoiding stall rest if at all possible and going slowly in any exercise program will reduce the risk of microfractures.
Finally, working with an independent nutritionist is a great way to balance the diet and make sure you are providing the right vitamins and minerals for bone health.
In Conclusion
There is increasing awareness of the role of Vitamin K in bone health, energy metabolism, and immunity, but little research has been conducted in horses specifically. At this point, there is not enough evidence for me to suggest Vitamin K containing bone supplements to clients. Based on my experience and the current research, it is best to focus efforts on proper training and diet.
Still have questions? Ask me! I’d love to talk with you further.
Resources
Vitamin K3-induced renal toxicosis in the horse. Journal of American Veterinary Medicine Association 184, 1237–1239. Rebhun WC, Tennant BC, Dill SG, King JM (1984)
Vitamin K and Bone Health: A Review on the Effects of Vitamin K Deficiency and Supplementation and the Effect of Non-Vitamin K Antagonist Oral Anticoagulants on Different Bone Parameters. Celia Rodríguez-Olleros Rodríguez and Manuel Díaz Curiel. Journal of Osteoporosis J Osteoporos. 2019; 2019: 2069176.
Vitamin K: history, metabolism, and nutrition in the horse Skinner, Jazmine E., Cawdell-Smith, A. Judy, Biffin, J. Ray, Regtop, Hubert L. and Bryden, Wayne L.. 2023.
The response of bone, articular cartilage and tendon to exercise in the horse. Journal of Anatomy Elwyn C Firth. 2006 Apr; 208(4): 513–526.