After multiple athletes asked me about supplements this week, I thought it was a good topic for a post! There are two supplements that I strongly recommend runners take. *Note that I am not a doctor or dietitian. These opinions are my own.*
First, I recommend an iron supplement (unless you’ve tested high for iron in the past). Runners can lose iron as mileage increases: with each foot strike RBC (red blood cells) are damaged. Runners also lose a little iron through their sweat and sometimes GI track. Female runners lose iron each month when they menstruate. If that iron loss isn’t made up for with a lot of iron-rich foods, you’re at risk for low iron and anemia – which will impact your ability to deliver oxygen to working muscles.
Low iron has a significant negative impact on your ability to train hard and race! I believe that an iron supplement of 100% of the RDV (18mg) is a good insurance policy against low iron/anemia but you may need more/less depending on your mileage, gender, how much iron you naturally take in via your diet, and other factors such as celiac disease (interferes with iron metabolism).
If you are interested to learn more about the science behind low ferritin and iron deficiency anemia, check out John’s article at Running Writings here. It is excellent, as is all the writing that he does. It’s everything you need to know, plus some! And, his articles present targeted information for runners (as opposed to information targeted more to the general population).
I also recommend a vitamin D supplement in the winter, especially if you live in a northern climate. Your body makes vitamin D when direct sunlight converts a chemical in your skin into an active form of the vitamin (calciferol). There are a lot of studies out there that point to the fact that over half of us (some studies quote much higher percentages! 60%, 80%) are vitamin D deficient. Our bodies can’t absorb calcium without vitamin D, so if you’re deficient, you’re at greater risk for stress reactions and stress fractures.
There have been some studies that link vitamin D with increased performance as well. For example, the 2009 Journal of Clinical Endocrinology & Metabolism concluded that adolescents with higher levels of vitamin D could jump higher, quicker, and with greater power than those with lower vitamin D levels. A 2008 review in Molecular Aspects of Medicine showed that vitamin D increased the size of fast-twitch muscles and muscular strength. We long distance runners aren’t as concerned with our fast-twitch muscles, but studies like this have to make you wonder what benefits distance runners could enjoy with vitamin D levels in the normal range.
I just had my blood tested, and I was shocked to find that I was on the lower end of the recommended range despite taking a daily vitamin D supplement. I was at 33 ng/mL, and my clinic stated the normal range as 30ng/mL – 80ng/mL. The Vitamin D Council suggests a higher range of 40 to 80 ng/mL with a target of 50 ng/mL.
I take a 1000 IU (international units) supplement daily and regularly train over my lunch hours, so I’m surprised that I’m as low as I was. The recommended daily amount of vitamin D is 600 IU for ages 1 to 70 years, and 800 IU for people over 70 years (per the Mayo Clinic’s website).
You’ve convinced me. But, what brand should I buy?
I don’t have a recommendation for a particular supplement brand to use. Supplements are not regulated by the FDA, and it’s hard to know who to trust. When I was training professionally, I used Nutrilite vitamins as they were NSF certified and I could be certain they didn’t contain other substances other than what was on the label. I really love their products (check out my review here), but I just can’t justify their $70/month price tag as a non-professional. I actually took a combination of their Double X multi-vitamin, fruits and veggies, and fish oil – all of which retailed at over $150/month.
I remember one conversation I had with a group of NYC Marathon Professional Woman’s Division racers about supplements, drug testing, etc. One woman said that she only used the Wal-Mart generic brand of vitamins and supplements. Her rationale? Wal-Mart was probably too cheap to put anything else into the supplement (other than what they had to). I remember walking the hallway back to my hotel room and suddently thought, “But what if they are too cheap to put what they’re actually supposed to put into the vitamin, though?”. I really wish that some governing body would start regulating supplements. I think it’s outrageous that the industry isn’t.