Despite looking and feeling well, thousands of Britons may be living with silent iron deficiency, as new research uncovers a hidden health gap affecting especially women of menstruating age.
Study: Ironically unwell: anaemia and iron deficiency among health-aware adults in the UK. Image Credit: Motortion Films/Shutterstock.com
Despite appearing healthy, thousands of UK adults unknowingly live with anemia and iron deficiency. A large UK-based study in Frontiers in Nutrition of over 33,000 health-conscious adults has found that 6% had anemia, with iron deficiency being the leading cause. The findings reveal that many cases go undetected due to a lack of symptoms, especially in women of menstruating age.
Background
Anemia is a health condition characterized by reduced red blood cell (RBC) count or hemoglobin concentration in the blood. It affects over 1.9 billion people worldwide, with women and young children being significantly more susceptible than men.
Anemia can develop for a variety of reasons, such as reduced production of RBCs, increased breakdown of RBCs, or loss of blood. Both absolute iron deficiency (insufficient iron stores) and functional iron deficiency (insufficient supply of iron for RBC production despite adequate stores) significantly contribute to the pathophysiology of anemia.
Iron plays a vital role in many physiological processes, including DNA synthesis and repair, and the functional regulation of enzymes, neurotransmitters, and mitochondria. The most common symptoms of iron deficiency include fatigue, hair loss, weight gain, muscle and joint pain, and heart palpitations.
Iron deficiency in people with anemia is associated with reduced physical and cognitive performance. During pregnancy, iron-deficient anemia can increase the risk of preterm labor and low birth weight.
As anemia and iron deficiency have become major public health concerns worldwide, the World Health Organization (WHO) has set a target to halve the incidence of anemia in females of reproductive age by 2030. This is likely to be challenging, however, as the incidence of anemia has remained relatively unchanged over the past three decades.
Although the prevalence of anemia and iron deficiency is higher in countries with low socioeconomic status, a high treatment burden related to these conditions has been observed within healthcare systems in high-income countries.
The current study aimed to determine the prevalence of anemia and iron deficiency in the UK adult population undergoing private health checks. It is important to note that this cohort represents health-aware individuals and does not necessarily represent the general UK population.
The study included a total of 33,029 apparently healthy individuals who underwent private health checks for general well-being assessment or for a specific health concern. Blood samples collected from the participants were analyzed to detect anemia and iron and vitamin deficiencies.
Study findings
The overall prevalence of anemia was estimated at 6% in the study population, with females having significantly higher prevalence than males. The highest prevalence of anemia was observed in females of menstruating age (18 to 50 years) and those aged over 70 years. This prevalence is similar to estimates from the Global Burden of Disease 2021 data, which reported a prevalence of 6.5% in the UK general population.
Severity varied across individuals, with the study reporting that about 78%, 21%, and 1% of the participants with anemia had mild, moderate, and severe anemia, respectively. The most commonly reported symptoms were fatigue, bloating, low mood, anxiety, and joint pain. However, more than 50% of participants reported no symptoms. Headaches were also noted as a common symptom among some anemic individuals.
The prevalence of absolute iron deficiency was estimated to be 17% in the study population, with females still having higher prevalence than males. In particular, nearly one in three females (31.6%) showed signs of absolute iron deficiency, with prevalence exceeding 35% in females aged 18-49.
Like anemia, the prevalence of absolute iron deficiency was highest among females of menstruating age. In contrast, absolute iron deficiency was observed in just 2.9% of males, emphasizing the gender disparity.
The symptoms of absolute iron deficiency were similar to those reported for anemia. About 52% of participants reported no symptoms.
The study found a high overall prevalence of functional iron deficiency (41%) among participants across all age groups and genders. However, this deficiency was more common among females than males. Although functional iron deficiency is not commonly screened in general populations, the study indicates an unexpectedly high prevalence and potential clinical relevance.
The authors stressed that further research is needed to clarify the clinical importance of functional iron deficiency, especially in health-aware but asymptomatic populations. At present, its role in clinical decision-making remains uncertain.
The study also identified the incidence of vitamin B12 and folate deficiencies in the study population. The overall prevalence of vitamin B12 deficiency was 1%, and folate deficiency was 3.6%, with a higher prevalence of possible deficiency observed in both cases.
In addition, the study found that a notable proportion of participants were classified as having “possible deficiency,” suggesting subclinical insufficiencies may be more widespread. The prevalence of folate deficiency was the highest among males and females aged over 30 years.
The research also included a separate analysis of the prevalence of iron and vitamin deficiencies among the anemic participants to identify potential causes of anemia. The analysis identified absolute iron deficiency as the primary cause, followed by functional iron deficiency. However, the study also found that approximately 11.5% of anemic individuals had no identifiable iron, vitamin B12, or folate deficiency, suggesting other contributing factors.
Conclusion
Prevalence of anemia was estimated at 6% in this health-aware UK cohort, according to the study. According to the WHO, prevalence of anemia higher than 5% is regarded as a mild public health. The majority of anemia cases identified in the study were mild in intensity. However, existing evidence indicates that even mild anemia can increase the risk of postoperative mortality and morbidity in patients undergoing major non-cardiac surgery.
Absolute or functional iron deficiency accounted for the majority of cases, and overall, iron or vitamin deficiencies were identified in nearly 74% of participants with anemia, indicating that iron deficiency is the major cause of anemia in apparently healthy adults.
The current study reports significantly higher prevalence of anemia and iron deficiency among females of menstruating age compared to males. Iron deficiency was more commonly identified in females who report regular menstruation or experience heavy menstrual bleeding.
Heavy menstrual bleeding is considered a significant risk factor for anemia or iron deficiency in females of menstruating age. Despite the widespread understanding that menstruating females are at higher risk of iron deficiency and anemia, screening programs for these conditions are largely lacking worldwide.
Notably, the current study reports that about 57% of participants with anemia and 52% with absolute iron deficiency do not experience any symptoms. Without the individuals undergoing private health tests, their anemia and iron deficiency may have gone unreported. The study findings highlight the significance of screening asymptomatic but at-risk populations to identify unnoticed anemia and iron deficiency.
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