Iron deficiency anemia among older adults weakens muscles, doubles the risk of death

SÃO CARLOS, Brazil — Taking iron supplements not only benefits people with anemia, but it may also prevent a life-threatening loss of muscle mass among older people.

A team from the Federal University of São Carlos in Brazil and University College London reports that suffering anemia and weak muscles at the same time can significantly increase the risk of death among older adults. The study shows this combination increases an older man’s risk of dying by 64 percent and by an astounding 117 percent among older women.

Anemia, which is a condition where people lack enough healthy red blood cells, contributes to a 58-percent higher chance of dying among men. Meanwhile, loss of muscle strength (dynapenia) is an even bigger risk factor for women, increasing mortality risk by 68 percent. However, study authors stress that the two conditions together pose even greater risks, particularly for elderly women.

“In the case of women, the risk of dying is doubled when the two conditions are combined. That’s a very significant increase, and so these factors should be monitored clinically. When patients go to the doctor, the cause of any anemia should be identified quickly and treated. It’s also important to discover the reason for any muscular weakness and prescribe resistance exercise,” says first study author Mariane Marques Luiz, a PhD candidate in physiotherapy at UFSCar, in a media release.

What’s the importance of iron in the blood?

The team analyzed data pertaining to 5,310 English people over the age of 50, provided by the English Longitudinal Study of Aging (ELSA). Scientists tracked all of those participants for a full decade. Marques Luiz explains that the study concluded overall mortality risk was higher among participants with anemia and dynapenia regardless of various other independent factors such as exercise habits, age, smoking habits, memory performance, marital status, difficulties with instrumental activities of daily living (IADL), heart disease, lung disease, and cancer.

“We analyzed all causes of death, and the results showed that a combination of anemia and dynapenia increases the all-cause mortality risk. Having both anemia and dynapenia is a significant risk for older people regardless of these problems,” the researcher explains.

Among the entire analyzed group, 84 percent were free of both anemia and dynapenia. However, 10.7 percent had dynapenia, 3.8 percent had anemia, and 1.5 percent had both. Over the course of the 10-year tracking period, 984 deaths occurred. Nearly two in three (63.7%) had neither anemia nor dynapenia, 22.8 percent had dynapenia, 7.5 percent had anemia, and six percent had both.

Prior research reveals that anemia is a risk factor for weakened muscle strength because iron captures oxygen found in red blood cells. Thus, less oxygen is able to reach the body’s tissues when a person is dealing with anemia. This leads to weakened muscles due to impaired oxygenation.

Scientists refer to poor oxygenation as hypoxia, and it can impact not only muscles but all bodily organs and systems.

“Hypoxia can cause a number of alterations in the organism, such as peripheral arterial vasodilation and reduced capillary formation. It can also trigger myocardial dysfunction and inadequately activate the [renin-angiotensin-aldosterone] hormone system that controls blood pressure, among other things,” notes corresponding study author Tiago da Silva Alexandre, a professor of gerontology at UFSCar.

All of the consequences connected to hypoxia consequently increase the risk of both cardiovascular disease and overall mortality.

“When older people have anemia, they’re more likely to have dynapenia, and when they have both conditions together, the problem is even more complex, because in addition to the hemoglobin and iron deficiency [characteristic of iron-deficiency anemia], low production of red blood cells and iron has an adverse effect on the musculoskeletal system,” Prof. Alexandre continues.

Why do these conditions affect men and women differently?

Study authors also focused on investigating if anemia and dynapenia affect men and women differently. The results certainly suggest that both conditions are more common in women, and more dangerous as well.

“First of all, there’s a mathematical question. Anemia is slightly more prevalent in women than men. It’s worth noting that the cutoff points to define anemia in each sex are different,” Prof. Alexandre says.

However, women also appear more likely in general to suffer the impact of anemia on their skeletal muscles.

“This difference may occur because men generally have more muscle mass than women, so that when men have anemia, the musculoskeletal system is less affected. That’s only one of the possible explanations,” Alexandre says.

The study finds dynapenia in and of itself is a mortality risk for women, but anemia is not.

“Women typically lose muscle mass as they age, and it may be the case that anemia adds to this loss,” Alexandre adds.

While men tend to have more muscle mass than women, generally speaking, males also lose muscle faster as they grow older.

“However, because women generally have less muscle mass, their strength may decline over time, and this affects mortality. Dynapenia is a sign that something is wrong with the health of an older person,” Prof. Alexandre concludes.

The study is published in the journal Archives of Gerontology and Geriatrics.

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