Micronutrient Misconceptions: Sodium and Iron

By Ben Connelly

When it comes to micronutrients, the operative question is, “how much?” Too much of a good thing can become a bad thing. While vitamins and minerals are vital to health, some can be harmful in high enough quantities. (Other will not harm you but will not provide any extra benefit.)

For marathoners, who need higher quantities of many micronutrients than nonathletes, this question of “how much” can seem tricky. A few rules of thumb help:

  1. It is hard to overdose on most vitamins and minerals from food sources. You need to take supplements to overdose.
  2. Do not take supplements unless you have a need (a deficiency, or an inability to get enough of a micronutrient from food). You may need Vitamin D supplements if you do not get much sunlight.
  3. Look out for extreme exceptions (usually uncommon foods or uncommon quantities of specific foods). Brazil nuts are considered superfoods, in part for their high selenium content. But if you eat 100 Brazil nuts at once, you could overdose on selenium. 

Outside rare cases, you do not have to worry about eating too much of certain vitamins and minerals. With that said, let us dive into two specific micronutrients that many have misconceptions about: iron and sodium.


I know runners who suffered from anemia. I know non-anemic runners who struggled with low iron. Many readers may as well. Runners in this category should absolutely take iron supplements. Some of them have conditions that hinder the absorption of iron from food. 

But many other runners have high levels of iron already. (More commonly men than women.) They do not need supplements. In fact, taking iron supplements might be harmful to their health and training. 

Certain tests can help determine your iron needs. My rule of thumb: do not take iron supplements unless prescribed them by a medical professional. Especially if you already eat a diet high in iron. At the same time, you do not need to worry about getting too much iron from food. It is very hard, or even practically impossible, to do so. You can eat all the spinach and red meat that you want.

For more information: https://runnersconnect.net/ferritin-levels-runners/


Many people fear salt. “Salt is bad for you,” is a common refrain. 

But this is misguided. All sodium is not created equal. Extremely high levels of sodium in processed foods have been linked to high blood pressure. But table salt has not. 

Actually, most runners are more likely to suffer from low levels of sodium than high levels. Sodium is an electrolyte. During and after long runs in the heat, you need to take in sodium. Most sports drinks and some gels contain sodium. You can also eat salty foods. 

In fact, salt is critical for avoiding hyponatremia (overhydration). Hydration is about more than just avoiding dehydration and overhydration, it is about balancing water intake with sodium (and potassium) intake. During a marathon, you will need to drink water and take in sodium in order to avoid both bad outcomes. During training, you will also need to consume plenty of water and salt in order to maximize recovery.

For more information: http://www.jeffgalloway.com/learn/hyponatremia/


Moderation is key for both diet and exercise. Training too much can have just as much downside as training too little. Same with eating. 

The best way to get the right amount of any micronutrient is to eat a nutritious diet (i.e., rich in nutrients), and only supplement if you have a genuine need. (Genetic tests can help you determine such a need. See the link at the end.) If you do have a deficiency, take supplements. 

Try to eat a relatively unprocessed diet. Highly-processed foods are problematic for many reasons. But if you want to avoid high blood pressure, you should avoid processed foods with high sodium content. 

Unprocessed foods are often very low in sodium. If you eat a very unprocessed diet, you should add sodium to your diet with table salt. In fact, the best strategy to balance your needs is to eat a relatively unprocessed diet, and then add table salt. 

When it comes to iron, sodium, or any micronutrient, you want to determine your own personal needs. If you are anemic and have high blood pressure, you want more iron and less sodium. If you have high iron and low blood pressure, you do not need extra iron and you should eat more salt. 

To determine your own nutritional needs, you can take genetic tests, or talk to a doctor or licensed medical professional. 

I also recommend checking out this link: https://www.foundmyfitness.com/genetics



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