Iron: too much and you’re at risk for liver disease; too little and you’re anemic. As much as 18% of Americans use a supplement containing iron, but a new study published in both the Journal of the American Heart Association and PLoS Medicine made connections between naturally occurring iron levels and more than 900 health conditions.
With more than half a million individuals’ genetic data making it possible, the study focused only on naturally occurring iron levels (as opposed to iron levels impacted by supplementation). Genetic variation leads to different levels of naturally occurring iron among individuals, just like genetic variation leads to blonde and brunette hair or short and tall people.
Interestingly, naturally higher iron levels were associated with potential benefits and potential risks that seemed, at least in part, contradictory.
Potential Benefits of More Naturally Occurring Iron
People with genetic variants leading to naturally higher iron levels were also (on average) associated with having a lower risk of high cholesterol levels. Too much cholesterol and it’ll build up in the arteries and increase the risk of blocking blood flow. More here
Additionally, naturally higher iron levels were associated with a reduced risk of clogged arteries, like what can happen with excessive cholesterol levels in the blood, which can lead to health conditions like stroke, deep vein thrombosis, and atherosclerosis.
Potential Health Risks Associated with More Naturally Occurring Iron
The study also found that higher naturally occurring iron levels were linked to higher risk of blood clots as a result of slow blood flow. More on poor circulation here
Higher naturally occurring iron levels was also found to be associated with higher risk of bacterial skin infection.
Making Sense of the Results
In a very unsatisfying conclusion, lead study author Dr. Dipender Gill essentially said that there is still a lot scientists don’t understand about how iron levels influence the relationship between cholesterol levels, circulation, and blood flow-related health conditions like stroke, deep vein thrombosis, and atherosclerosis.
It’s likely that the same genetic variation responsible for different levels of naturally occurring iron influences individual risk for conditions like high cholesterol, poor circulation, or stroke. Perhaps in future studies, Gill and the research team will control for different factors (age, sex, BMI, etc) to see what health differences make higher naturally occurring levels of iron beneficial versus potentially harmful.
As a component of hemoglobin, iron helps carry oxygen around to the body’s tissues like the wheels of a taxi carrying humans from point A to point B. In addition to being oxygen’s preferred form of transportation, iron provides support for:
- Growth and development
- Normal cellular functioning
- Hormone production
- Connective tissue production
So yeah, iron is pretty important. But the name of the game when it comes to iron intake is balance. Too much? Liver damage. Too little? Anemia.
Recommended Dietary Allowances (RDAs) for iron intake vary based on age and, for women, pregnancy status (PSA: these recommendations were developed by the Food and Nutrition Board (FNB) at the Institute of Medicine (IOM) of the National Academies (formerly National Academy of Sciences)).
You can get iron from all sorts of dietary sources. Plants like nuts, beans, and vegetables along with iron-fortified foods contain nonheme iron, while meat, seafood, and poultry contain both nonheme and heme iron, which is more biologically available, or bioavailable, for absorption during digestion. Think of it like this: an amount of iron in a piece of steak is more “valuable” to you than the same amount of iron in your spinach salad. Heme iron gives you more bang for your buck. That being said, vegetarians and vegans need to eat a lot more to get enough iron for good health.
Iron Supplements: Synthetic and Whole Food
The average iron supplement provides 18 mg of iron. However, multivitamins for women most always contain iron while multivitamins intended for men and for seniors often do not. Iron-only synthetic supplements typically deliver more than the RDA, as much as 360% (65 mg).
Whole food iron supplements usually contain a percentage of iron that’s closer to the RDA, closer to 10%. Ingredients in natural supplements based on whole foods are arguably more bioavailable than synthetic supplements because they imitate how those ingredients are found in nature. So the 10% of iron in a whole food supplement will be absorbed in the body at a higher rate than the 360% in the synthetic supplement. Natural supplements that deliver a nutrient in its “natural habitat” – a whole food matrix. This delivery method is more aligned with what the body needs. Although, ultimately a whole food source of iron is the superior choice to any sort of supplementation.
What other questions do you have about iron? Let me know at ScienceKara@gmail.com
*Courtesy of the National Institutes of Health Office of Dietary Supplements