Iron Deficiency Linked to Coronary Artery Disease Risk
Heart disease is the number one killer of men and women in the U.S. About 610,000 deaths yearly are attributed to some form of heart disease. If we can identify risk factors for cardiac disease, then we have an opportunity to save lives. A study published in Arteriosclerosis, Thrombosis and Vascular Biology suggests that there’s a link between levels of iron in the body and the risk of developing coronary artery disease (CAD).
Coronary artery disease is commonly a result of atherosclerosis or hardening of the arteries. This phenomenon is typically caused by plaque buildup in the lining of arteries. Coronary artery disease is a risk factor for angina and heart attacks. About 370,000 deaths yearly are attributed to CAD.
When people complain of fatigue or feeling run down, low iron level is often blamed (remember the cartoon with Popeye guzzled cans of spinach?) Though fatigue is not always a first sign, low levels of iron are of concern. The cause of anemia due to low iron levels needs to be determined. Unidentified bleeding, a serious health issue, needs to be ruled out. Low levels of iron mean that hemoglobin levels will fall short. Hemoglobin helps to transport oxygen levels through the body.
Men (age 19 and older) need about eight milligrams of iron daily while women (age 19 to 50) need about 18 milligrams of iron daily. Women over age 50 need about eight milligrams of iron daily. There are also specific needs for iron during pregnancy and lactation.
Dietary iron comes in two main forms – heme and nonheme. Plants and iron-fortified foods including beans, peas, seeds, nuts, vegetables (beets, dandelion, mustard greens, kale, leeks, spinach), and fortified grains contain nonheme whereas meat, eggs, seafood and poultry contain the heme form. Most of the three to four grams of elemental iron in the body is in hemoglobin. The rest of the iron is stored in the body. Serum ferritin levels can identify low levels of iron in the body.
The amount of nonheme absorbed during meals depends on other foods eaten at that time. Foods containing heme enhance absorption of nonheme iron. Foods containing vitamin C also enhance absorption of nonheme iron so it’s a good idea to eat fruits or vegetables high in vitamin C when consuming nonheme sources of food. Polyphenols and phytates can interfere with iron absorption too, so, for example, don’t take an iron supplement with tea.
You can also get iron from supplements. Different forms of iron in supplements contain differing amounts of elemental iron. Supplements offer ferrous sulfate, ferrous gluconate, ferric citrate and ferric sulfate. Experts suggest taking iron and calcium supplements at different times because calcium may interfere with iron (nonheme) absorption. Antacids can reduce the amount of acid in the stomach and lower iron absorption too.
Rates of iron deficiency vary by race and sociodemographic factors. Groups at risk of iron deficiency include pregnant women, infants and young children, women during heavy menstruation, frequent blood donors, people with cancer, and people with gastrointestinal disorders, and people with heart failure. If vegetarians or vegans are not “tracking” foods with iron in their daily diet, they may also be at risk of low iron levels. Iron deficiency can also occur after gastric bypass surgery.
Previous research in the journal Circulation suggested a link between coronary heart disease and iron levels but results weren’t consistent regarding benefits or downside of higher levels of iron. A 2013 study also suggested a possible benefit from maintaining levels of iron and reducing cardiovascular disease. This new study used a randomized approach to look at the link between iron and heart disease risk more definitively. The researchers looked at people’s individual genetic variations trying to eliminate any confounding (lifestyle, environmental) factors.
The study examined genetic data from 48,000 subjects. They focused on single nucleotide polymorphisms (SNPs) looking for either high or low iron status. SNPs are used to find genetic locations for certain diseases. The researchers then screened for the SNPs among 124,000 subjects.
They found clear evidence that higher levels of iron reduce the risk of developing coronary artery disease. That means there might be a therapeutic value in targeting specific iron levels to prevent CAD.
The researchers suggest that randomized trials to test iron supplements versus placebo are indicated to see if giving supplemental iron actually helps to prevent CAD. They suggest that similar to giving a person a statin to reduce cholesterol levels, giving supplemental iron if iron levels are diagnosed as low may help lower risk of a specific type of heart disease. This could be especially beneficial if there is family history of CAD or if someone has already had a heart attack.
It’s important to note that health risks can also occur from excessive iron intake. They can range from gastrointestinal upset and constipation to multi-system organ failure, coma and death, depending on blood serum levels.
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