Health - Iron - Anamnesis

A lack of this vital nutrient is one of the world's leading causes of disability – but exactly when it becomes a problem, and the best way to treat it, remains unclear.

When Megan Ryan first noticed her fatigue, she assumed it was normal. After all, she was a single parent to a three-year-old. She also worked full-time. Almost every day, when she picked her son up from daycare, she'd fall asleep with him during his afternoon nap. She didn't think much about it. "I just thought, 'Oh, this is motherhood'," says Ryan, who lives in upstate New York, US. At a routine medical check-up in June 2023, her doctor asked if she felt exhausted. Blood test results showed that Ryan had iron deficiency anaemia.

Looking back, there had been other signs. Despite regularly working out, Ryan had suddenly started to feel winded on routine hikes. She had also had iron deficiency before, during pregnancy. That time, her midwife suspected it after Ryan mentioned that her only pregnancy craving was ice – a classic sign of pica, which is, in turn, a symptom of iron deficiency. 

Iron deficiency is the most common micronutrient deficiency in the world today, affecting roughly one in three people. It is especially prevalent among children as well as women of reproductive age, including pregnant women.

The condition can cause a wide range of consequences. When a pregnant woman doesn't have adequate iron stores, for example, it can affect the foetus' brain development and there is also a higher risk of low birth weight, preterm birth, dying during pregnancy and stillbirth. For babies and toddlers, not having enough iron can affect long-term development, with studies finding that children are at risk of exhibiting behavioural issues – they are less happy and contented, and tend to be more socially inhibited. It can also influence children's motor skills, and cognitive ability even years after a deficiency has been corrected. In adults, iron deficiency is one of the world's leading causes of disability. In rare cases, it can be life-threatening.

A widespread issue

"It's a major global problem," says Michael Zimmermann, professor of human nutrition at the University of Oxford in the UK and a long-time researcher of micronutrient deficiencies. "It's very common. It's not going away very fast. And it is associated with a lot of disability."

Most scientists agree that iron deficiency is a common condition. But other questions persist, such as how exactly to define iron deficiency, or how likely it is, in the absence of other symptoms, to raise the risk of poor health outcomes. So, when should, and shouldn't, someone supplement their iron? 

What isn't disputed is that some groups are more susceptible to iron deficiency than others.

In women, for example, iron-deficiency anaemia – where the body does not have enough iron to make sufficient red blood cells – is a leading cause of disability worldwide. One study of first-time US blood donors found that iron levels were low in 12% of women, but in less than 3% of men, reflecting the impact made by regular blood loss through menstruation. Then there's the impact of pregnancy, which diverts nutrition to the foetus, meaning that women in this group are particularly at risk. One study found that 46% of UK women had anaemia at some point during pregnancy – though not all cases stemmed from iron deficiency.

Endurance athletics, vegetarianism or veganism and frequent blood donation can all put both men and women at increased risk. People with certain health conditions might also be prone to lower iron levels. Kidney disease and coeliac disease can decrease iron absorption, for example.

A critical time

But children are among the most vulnerable group to iron deficiency because the mineral is so important for their development.

"What's the most rapid period of growth in our entire lifespan? Infancy," says Mark Corkins, chair of the Committee on Nutrition at the American Academy of Pediatrics (AAP). "You triple your birth weight by a year of age. You double your length." As our bodies grow, they need more blood. And red blood cells are built – in part – on iron. Without that necessary iron, says Corkins, you risk not able to produce enough red blood cells to deliver oxygen to your growing tissues, including the brain.

Iron deficiency is especially common in children from lower income countries. "In studies I've done in Africa, 70% of babies between six and 12 months of age have clear iron-deficiency anaemia," says Zimmermann.

Even in wealthier countries, which have better overall nutrition and which are more likely to fortify certain food products with iron, this deficiency persists. Up to 4% of toddlers in the US, for example, have iron-deficiency anaemia, while some 15% have iron deficiency.

Just because someone is iron deficient does not necessarily mean they will have anaemia. "Iron deficiency can be considered a stage prior to anaemia," says clinical haemotologist Sant-Rayn Pasricha, the head of the Melbourne School of Population and Global Health who specialises in iron deficiency and related conditions.

The severity of the deficiency plays a key role, Pasricha explains. When someone gets low on iron, their body begins to form red blood cells differently, he says. They get smaller and, eventually, the amount of oxygen-carrying haemoglobin in that person's blood drops below a healthy level. "That's when we reach iron deficiency anaemia," Pasricha says.

Iron deficiency and anaemia are generally diagnosed with a blood test – usually one that examines levels of ferritin, a protein that helps store iron, or haemoglobin.

The post on health and wellbeing continues..

- Author: Amanda Ruggeri, BBC