Anaemia is a disease which mainly presents as an abnormally low level of red blood cells or haemoglobin, which is necessary to transport oxygen throughout the body.
“Anaemia is not considered a natural consequence of the aging process,” said the study authors.
“[In the elderly, it] may be the result of nutritional deficiencies of key nutrients, such as iron, folate, and vitamin B-12. [Animal] products, particularly fish and meat, are excellent sources of vitamin B-and iron (haeme iron), [which is crucial for haemoglobin production.
“The current study in Japanese elderly [suggests] that higher animal protein, specifically the high protein content of fish, may be associated with a lower prevalence of anaemia.”
The study was conducted on over 6,000 subjects over the age of 65 in Japan across nine years, using data from the National Health and Nutritional Survey in Japan (NHNS). The subjects’ dietary habits and blood were analysed, and anaemia was defined according to the World Health Organisation definition as hemoglobin concentrations of less than 13.0 g/dL in males and 12.0 g/dL in females.
“[Both anaemic male and female subjects] tended to significantly consume less fish compared with non-anaemic subjects, [and the same] was found for meat consumption in males” stated the study.
In males, this was a median value of 86g of fish per day in anaemics versus 100g per day in non- anaemics, and 38.6g of meat per day in anaemics versus 49.8g per day in non-anaemics. Anaemic females consumed 73.5g of fish per day versus the 83.5g consumed by non-anaemics, but both groups took 30g of meat a day.
“This study indicated that fish intake was associated with lower anaemia risk, independent of dietary energy intake and major lifestyle confounders in Japanese elderly,” said the authors.
Two possible explanations offered were that animal protein can help with the reduction of skeletal muscle mass (previously suggested to heighten anaemia risk) loss, and with supporting the formation of red blood cells.
“[Higher] animal protein, specifically the high protein content of fish intake appeared to be related to preservation of skeletal muscle mass,” said the study.
“Sufficient animal protein intake may [also] have a positive effect on red blood cell formation and reduces the risk of malnutrition and anaemia.”
Other tests conducted on individual nutrients such as vitamin B12, iron and folate did not reveal significant associations with anaemia, leaving the fish and meat consumption in the subjects’ diets as the main association.
“[The] lower risk of anaemia is likely explained [by] the intake of animal protein, specifically the high protein content of fish.”
Different types of anaemia
In addition, the study looked at both microcytic anaemia, which occurs in the case of iron deficiency, and macrocytic anaemia, which occurs in vitamin B12 or folate deficiency.
“Microcytic and macrocytic anaemia [rates] did not differ between the anaemic and non-anaemic group,” said the authors.
“Fish contains significant amounts of animal protein [but not so much of] these anaemia-related nutrients. Therefore, it is possible that not vitamins but animal protein intake may be related to lower anaemia risk, and animal protein intakes [are] helpful in preventing anaemia in elderly populations.”
Meat could have a more significant role
That said, the authors stated that meat could actually play a larger role than observed in this study, as it is consumed far less in Japan as compared to fish.
“In Western countries, the major sources of animal products are meat and poultry, whereas Asian populations, particularly the Japanese elderly, tend to consume more fish but less meat,” they said.
“Meat intake was much lower compared with that in Western countries, therefore, meat intake was not significantly associated with lower anaemia risk.”
Citing a previous Brazillian study conducted in 2013, they said that meat had been found to be the more significant deterrent of anaemia, whereas a 2011 United States study reported that women with anaemia had consumed less red meat.
Study: Fish and meat intakes and prevalence of anemia among the Japanese elderly.
Authors: Imai, E. et. al.
Source: Asia Pacific Journal of Clinical Nutrition