The statement "you are what you eat" is actually a biologically correct concept akin to bioaccumulation, in which the nutrients at the bottom of a food chain carry through organism after organism, increasing in concentration as they reach the top of the chain.
It should be unchallenged that increased nutritional content in foods or feeds would pass through to the eater, or else all of nutritional research on supplements and even the science of feeding livestock would be a waste.
Therefore when science shows forages and foods that come from soils rich in life and a wide variety of nutrients, we can assume they provide higher nutrient value to the consumer. A little logical extrapolation suggests improvements in human health are possible from creating healthier soils and eating the livestock products that come from it.
Soils and agronomy researcher Jill Clapperton of Montana has shown that soil nutrients created by healthier soils and cover crops pass through to grain crops. In one study she described recently, various cover crops showed an affinity to put more of some nutrients and less of others. For example, a cover crop of pea, hairy vetch and oats produced high levels of manganese, phosphorus, zinc, magnesium and sulfur in a follow-up crop of hard red spring wheat. In comparison, a cover crop of crimson clover, chicory and oats produced strong levels of phosphorus, magnesium and potassium. A cover crop of faba bean, peas and oats produced in the wheat the highest overall levels of everything except iron. A mix of lentils and phacelia, however, produced the highest iron content in the follow-up wheat crop.
Advantages from building healthier soil can be seen in data from 2016 on Gabe Brown's farm in North Dakota. That shows regenerative farming and high-stock-density grazing together dramatically increase the basic elements of nitrogen, phosphorus and potassium, as well as water-extractable organic carbon. See the chart with this table, but an example of this difference is that no-till with low plant diversity produced 30 kilograms per hectare of nitrogen, no-till with medium plant diversity and high synthetic fertilizer produced 41 kilograms per hectare of nitrogen, and no-till with high plant diversity and livestock grazing produced 315 kilograms per hectare of nitrogen.
Pasture quality affects wool quality, explained Australian soil scientist Christine Jones, who explained how her work soon after graduating from college began her education about pass-through nature of soil nutrients. She explained her first full-time job after graduation involved research into the wool parameters that affect processing performance. Unless wool fibers have an even diameter all the way along their length — and high tensile strength — they break easily and are difficult to spin into yarn. She learned that wool quality is influenced by pasture quality, which in turn is affected by soil quality.
Conversely, the damage to soil from conventional farming is shown in data from an ongoing study in the United Kingdom. The nutrient value of four different food types has declined significantly as soils worldwide have become increasingly damaged since 1941. McCance and Widdowson's The Composition of Foods, shows calcium dropped 46% in vegetables, 16% in fruit, 29% in meats, but increased 4% in dairy. Iron dropped 27% in vegetables, 24% in fruit, 50% in meats and 83% in dairy.
Soil scientist William Albrecht was a big advocate of soil health as a precursor to human health. He made a study of US Army acceptance and rejection of troops for World War II based on health of the soil, wherein 70% of young men from areas with good soil were selected for service, versus 70% rejected in some of the southern states "where the soils are more exhausted of their fertility." This was in a time when close to 90% of people lived on the farm and ate food raised on their own farm. Albrecht also noted that the 5% of human body makeup from minerals in the soil has vast effect on the other 95% of the body.
In beef cattle, we are slowly acquiring more knowledge about how grain-finished versus grass-finished makes subtle but possibly important differences in fatty acid makeup of the meat, which in turn appears to have significant effect on human health issues such as inflammatory reactions. Even if you care to argue the human health value of these differences, the data shows where the cattle are concerned, clearly that what goes in affects what comes out.
Another example of soil nutrient pass-through is explained in a research paper on nutrient profiles in grass-fed beef published in Nutrition Journal in 2010. "Carotenoids are a family of compounds that are synthesized by higher plants as natural plant pigments. Xanthophylls, carotene and lycopene are responsible for yellow, orange and red coloring, respectively. Ruminants on high forage rations pass a portion of the ingested carotenoids into the milk and body fat in a manner that has yet to be fully elucidated," the researchers wrote.
A simple look at vitamin E feeding studies shows significant increases in muscle and fat content of vitamin E in fed-steer carcasses after slaughter when they are fed vitamin E versus those not fed vitamin E.
In the June 2017 issue of Beef Producer we showed how arbuscular mycorrhiza fungi (AMF) is one of the key components in creating healthier soil and therefore healthier plants, and how that condition is built by grazing management to allow full plant recovery and deep rooting, and by multi-species cover crops with no tillage and complete soil coverage. We also described how these multiple plants species, as well as the deepest-rooted plants, trade carbon compounds for nutrients mined by AMF and their associated bacteria and other organisms. This is the method by which nitrogen, phosphorus and potassium all become available from what's already in the soil, as well as the trace minerals and many beneficial compounds such as phytonutrients, which are chemicals plants use to help protect themselves from germs, insects and other threats. In turn, they have health benefits for animals consuming the plants.
Some nutrients, phosphorus being a prime example, are quickly bound in the soil to other nutrients and without regular applications as added fertility, will be insufficient in plants under contemporary agricultural practices. With healthy soil containing plenty of AMF and associated bacterial colonies, however, there never seems to be a shortage of phosphorus.
By this type knowledge it appears we are moving toward understanding the relationship between vibrant and varied soil life and nutrient density of forages and feedstuffs, and then nutrient density of beef and other products from grazing animals.