Human health

Animal source foods are advantageous for populations with elevated needs

Benefiting populations with elevated needs

The global food security challenge is less about providing sufficient food quantities and calories than about ensuring an adequate supply of essential nutrients, including quality protein and various minerals and vitamins. Meat, dairy, eggs, fish, and seafood offer convenient and comprehensive nutrient packages that support both healthy growth and aging. For pregnant and lactating women, infants, and young children, they provide nutrients that are essential for proper development, such as iron, vitamin A, zinc, and calcium. In older adults, they help combat undernutrition, functional impairment, cognitive decline, and sarcopenia. Adequate protein intake, especially from animal sources, becomes more critical with age. Additionally, animal source foods are valuable for individuals with metabolic health issues. While meat consumption is often associated with better mental health, its avoidance parallels a higher risk of certain mental disorders. Furthermore, intervention trials demonstrate that incorporating animal source foods into diets can prevent deficiencies, support growth, development, and overall health in various population groups.

This subsection addresses the following five questions:

What is the global food security challenge and how do animal source foods fit in?
Which vulnerable populations benefit from animal source foods, and how?
How are animal source foods associated with nutritional adequacy?
What is the relationship between animal source foods and mental health?
What do intervention studies tell us about the nutritional contributions of animal source foods?

What is the global food security challenge and how do animal source foods fit in?

Many populations, including in high-income countries, struggle to meet recommendations for several priority nutrients. Animal source foods contribute to the solution by enhancing nutrient sufficiency beyond staple foods and biofortification. Eggs and milk are accessible options for low-resource populations and contribute to healthy growth. Despite an increase in ASF intake among children and adolescents globally, Sub-Saharan Africa still faces disproportional deficiencies in key nutrients that are particularly bioavailable in ASFs, such as iron, zinc, iodine, and vitamin B12.

Which vulnerable populations benefit from animal source foods, and how?

Special attention is needed for pregnant and lactating women, infants, children, adolescents, and older adults due to their susceptibility to suboptimal micronutrient levels. Strict vegetarian diets can lead to severe consequences, as evidenced by clinical case reports for both young individuals and adults. Proper nutrition during early childhood is crucial for lifelong health, and complementary foods should include nutrient-rich options like meat, poultry, fish, or eggs. In older adults, animal source foods play a vital role in healthy aging, addressing undernutrition, cognitive decline, functional impairment, and sarcopenia. People with metabolic health issues also benefit from sufficient intake of animal source foods. Given the associated health care costs, the societal impact of addressing these nutritional needs is substantial.

Further reading (summary of the scientific literature):

Pregnant and lactating women and young populations

Pregnant and lactating women, infants, children, and adolescents deserve particular attention as they often suffer from suboptimal micronutrient levels [see elsewhere]. In case nutrient adequacy is not met, consequences can be severe for individuals on (strict) vegetarian diets, as documented by clinical case reports for both (very) young individuals [see elsewhere for a literature overview] and adults [Hines 1966; Carmel 1982; Milea et al. 2000; Brocadello et al. 2007; De Rosa et al. 2012; Noh et al. 2013; Førland & Lindberg 2015; Hsu et al. 2015; Nimmagadda et al. 2018; Bachmeyer et al. 2019].

Because appropriate feeding in early childhood is critical for health throughout the course of life, 'complementary foods should be rich in nutrients and given in adequate amounts [so that] young children should receive a variety of foods including meat, poultry, fish or eggs as often as possible' [WHO 2011]. In young children, the top food sources of commonly lacking micronutrients in low- and middle-income countries are all animal sourced: iron (chicken liver), vitamin A (ruminant liver), zinc (ruminant meat or small dried fish), folate (chicken liver), vitamin B12 (ruminant liver), and calcium (small fish) [Beal et al. 2021; White et al. 2021]. For example, compared with ruminant liver, children 6–23 months would need more than 100 times the portion size of pulses to achieve a similar level of adequacy of these critical micronutrients [Beal et al. 2021; White et al. 2021].

Older adults and healthy aging

In older adults, the role of animal source foods in healthy aging is of particular importance and more research is needed to weigh potential benefits against harms [Kouvari et al. 2016]. Recent studies indicate that a higher intake of animal source foods contributes to addressing the wide prevalence of undernutrition [Borkent et al. 2020], functional impairment [Yuan et al. 2020; Miyazaki et al. 2023], cognitive decline [Gao et al. 2022; Anderson & Alpass et al. 2024], and sarcopenia [Rondanelli et al. 2015], and may parallel lower mortality [Meroño et al. 2021; Kurata et al. 2023]. In a Japanese cohort, the consumption of milk in middle age has been associated with a lower prevalence of frailty later in life for men (but not for women) [Hong et al. 2024]. Fish consumption is associated with a lower risk of cognitive impairment and decline in a dose-response manner [Godos et al. 2024]. Frequent consumption of eggs has been related to a lower risk of Alzheimer’s dementia, possibly based on a higher intake of choline [Pan et al. 2024].

Low intake of protein is of particular concern in older populations [Langsetmo et al. 2020; Borkent et al. 2023], whereby the intake of animal protein over plant protein seems favourable to combat sarcopenia [Campbell et al. 2023]. A vegan diet should not be recommended without protein supplementation as it may lead to lower muscle mass and a higher risk for loss of physical function due to sarcopenia [Domić et al. 2022]. For more on the importance of protein quality when comparing animal source foods with plants, see elsewhere. The Irish Food Safety Authority specifically recommends animal source foods and, to a lesser extent, legumes and nuts to supply older adults with sufficient high-quality protein [FSA Ireland 2021]. Avoiding animal source foods increases the risk of inadequate protein intake, as strategies to improve the anabolic properties of plant-based foods are often not feasible for older adults [Domić et al. 2022].

In addition, elderly are more reliant on the few dietary sources of vitamin D (oily fish, eggs, liver, butter, meat), since their capacity to form 7-dehydrocholesterol in the skin is decreasing with advancing age [Bender 2002]. They especially benefit from high-quality protein supply [Bauer et al. 2013; Paddon-Jones et al. 2015; Medonça et al. 2020], which is more complicated when using plants only [Berrazaga et al. 2019]. Aging populations also become more vulnerable to B12 deficiency [Green et al. 2017]. Moreover, it is known that higher levels of total cholesterol and iron serve as biomarkers for longevity in Swedish centenarians [Murata et al. 2023].

The metabolically unhealthy

Finally, the metabolically unhealthy are an important target population group that would benefit from sufficient intake of animal source foods. They suffer from inflammatory conditions and perturbed endocrine responses (in particular hyperinsulinemia), which can at least be partially mediated via higher protein bioavailability [cf. Wolfe et al. 2008]. In Ireland, for instance, >80% of older adults are abdominally obese, while >50% are at high risk of cardiometabolic disease [FSA Ireland 2021]. The societal impact is gigantic, also because of the very high costs related to the treatment of such diseases.

How are animal source foods associated with nutritional adequacy?

Very low intake of animal source foods among vulnerable populations is often linked to decreased nutrient intake and compromised health. In contrast, various studies highlight the associations between the consumption of animal source foods and improved nutrient intake and health outcomes in different groups with elevated needs. Higher meat consumption can be linked to reduced anaemia among elderly, as well as decreased stunting in young children. Dairy consumption is, for instance, associated with an improved status of B-vitamin and vitamin-D biomarkers in older adults. Intake of fish is linked to improved nutritional outcomes, including a better vitamin D status in maternal diets and children's diets. Egg consumption is associated with higher intake of various nutrients, including choline. It is important to underline, however, that such associational data is not necessarily proof of causal relationships.

What is the relationship between animal source foods and mental health?

Many studies have indicated an inverse association between meat intake and mental health issues, although the causal direction is uncertain. Two potential explanations arise: 1) vegetarianism might serve as a cover for underlying mental disorders and eating pathologies, 2) poor mental health could result from nutrient deficiencies or low cholesterol levels. For example, low prenatal meat consumption has been linked to an increased risk of substance abuse in adolescence, potentially linked to vitamin B12 malnutrition. Some studies have found higher rates of depressive episodes among vegetarians compared to meat consumers. While (semi-)vegetarian women might demonstrate positive factors like physical activity and lower body mass indices, they could also report more menstrual problems and poorer mental health. The complex nature of the relationship is underscored by findings that semi-vegetarians with strong orthorexic tendencies tend to exhibit more depressive symptoms than both omnivores and vegetarians. In the elderly population, very low meat consumption has been connected to a higher incidence of dementia and Alzheimer's disease. Overall, the intricate interplay between meat consumption, vegetarianism, and mental health necessitates further comprehensive investigation to elucidate the underlying mechanisms and relationships.

What do intervention studies tell us about the nutritional contributions of animal source foods?

Intervention trials have shown that the incorporation of animal source foods in the diet can enhance nutritional resilience across different life stages, especially when the baseline intake is low. Their administration can help to improve the physical, behavioural, and cognitive outcomes of children, mitigate deficiencies in young females, enhance muscle synthesis in young men, and tackle poor bone health and sarcopenia in older adults. In Kenia, the administration of meat improved the performance of school children. Seafood, rich in long-chain omega-3 fatty acids, protein, and many other nutrients, contributes to improved responses in risk factors for chronic disease and has potential to reduce inflammation. Dairy products have demonstrated various health benefits, including improved vitamin K2 status, enhanced cognitive outcomes in school children in Ghana, and better bone health in various young and adult population groups. In rural Ecuador, it has been shown that eggs contribute to a reduction in stunting and improved plasma levels of essential nutrients like choline and DHA in infants.

Share this page on: