Health-promoting phytonutrients are higher in grass-fed meat and milk.

The controversy regarding animal products and human health and environmental concerns has not yet subsided, despite recent evidence which on the one hand shows that the relationship with cardiovascular disease, cancer and diabetes is largely inconclusive, and on the other hand environmental damage can be managed by production system management, such as regenerative management techniques. While it is recognised that milk and meat provide many essential nutrients including bioavailable protein, zinc, iron, selenium, calcium and vitamin B₁₂, less is known about other health-promoting phytonutrients such as terpenoids, phenols, carotenoids and anti-oxidants.

Several phytochemicals are found in milk and meat of cattle that graze a diverse array of plants on pastureand are often present in quantities comparable to those found in plant foods known to have anti-inflammatory, anti-carcinogenic and cardio-protective effects. As milk and meat are often not considered as sources of phytochemicals, their presence has remained largely under-appreciated in discussions of nutritional differences between concentrate-based (TMR, feedlot etc) and pasture-based dairy and meat. The literature is rather limited and mainly focused on the ω-3 fatty acids and CLA. Limited studies though, do suggest that grazing cattle on plant-species diverse pastures (mixed species) concentrate a wider variety and higher amounts of phytochemicals in milk and meat compared to grazing monoculture pastures, while phytochemicals are further reduced or absent in milk and meat of concentrate-fed cattle. In terms of mixed species which simulate natural rangeland, one suspects that the co-evolution of plants and herbivores has led to plants and crops being more productive when grazed in accordance with agro-ecological principles. Thus, the increased phytochemical richness of productive vegetation should probably have potential to improve the health of cattle and also humans. Some studies do suggest increased anti-oxidant activity in milk and meat of pasture-fed compared to concentrate-fed cattle, while there is also limited evidence that pasture-fed milk and meat consumption may have anti-inflammatory and improved lipoprotein profiles in humans. However, current knowledge does not allow for direct linking of cattle production practices to human health.

The authors cited recommended that future research should systematically assess linkages between the phytochemical richness of cattle diets, the nutrient density of animal products, and the subsequent effects on human metabolic health. Addressing this research gap will require greater collaborative efforts between agriculture and medicine.