A friend at the barn recommends a specific supplement. You read about it online. It seems to have a lot of good ingredients. What are some of the things that you need to think about when assessing a supplement?
◆︎ Purity of the supplement:
➡ The first thing to think about is the purity of the supplement. For instance, if you purchase resveratrol from My Best Horse, the purity is 98%+. However, resveratrol can also be purchased as 10%, 50%, 75%, or 90%. Does the product disclose the purity? Or do they mention that it is an “extract” without disclosing the percentage?
➡ Besides purity, it’s important to think about the amount of the active ingredient. For instance, milk thistle from My Best Horse is 63% silymarin. However, milk thistle seeds usually have only 2-3% silymarin.
Sometime a cheaper product is cheaper because it has less of the active ingredients.
◆︎ Serving size:
➡ Density variation. Although it’s recommended to use a gram scale for the most accurate measurement of a serving size, we frequently use common measurements – a scoop, a teaspoon, or a tablespoon. When using a scoop, is it light and fluffy? Or is it towards the bottom of the bag where it may be heavy and compact? (Think baking flour – it can be very fluffy, or it can be heavy and dense.)
➡ Actual amount of the supplement in the product. Besides density variation, there are some supplements on the market that list 40 different ingredients in a 30 gram scoop. Many of those ingredients could be at such low levels that it does not make a difference to the horse.
Example 1: 1% of pea protein is added to a supplement. In a 30 grams scoop, it would provide about 1.5 grams of the limiting amino acid lysine. Most horses would benefit from 10 grams of lysine added daily.
Example 2: You have someone balance your hay. They report that you need 300 mg of copper and 900 mg of zinc added to your supplement. A popular supplement contains 110 ppm of copper and 1000 ppm of zinc. The recommended serving size is 132 grams. After doing some math calculations, you discover that the copper in the supplement is 14 mg; the zinc in that same supplement is 132 mg. Clearly, this supplement would be insufficient to meet your balancer’s recommendations.
One of the difficulties in determining the amount of an ingredient in the supplement is that the units can be expressed in different ways – ppm, percentage, mg/lb, or other measurement. This can make the math confusing.
◆︎ Fillers:
Are you paying for fillers? There are pros and cons:
➡ Pros for fillers: Fillers may make supplements more palatable, so that your horse actually consumes them. They may be tastier than the bucket that you create. They may also make it easier to administer, without the worry about powders being stuck to the bottom or sides of the bowl.
➡ Cons for fillers: Fillers may also contain items that you may want to avoid. For instance, they may contain molasses or oats, which are contra-indicated for insulin resistant horses.
◆︎ Take home message:
For a better understanding of what you’re giving your horse, the following are important:
☛ Read the labels to see exactly what is in the supplement.
☛ Spend some time to do the math to ensure that the amounts are suitable.
☛ If you’re confused about the amount of an ingredient, ask someone for help with the math and/or conversions.
☛ If you have a question about the amount or purity of an active ingredient, feel free to reach out to the company with the questions you have.
We do the best that we can do for our horses.
Disclaimer: Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition.
©Joan Kulifay, MSc. 2025