Nutrient density (ND) refers to the amount of nutrition in food relative calories. Nutrition defined.
Test two carrots for vitamins, minerals, etc. and one is bound to have more nutrition than the other – one is likely have greater nutrient density. Another way to think about it is that one of those carrots, has more carrot in it! The variation can be tremendous. So what controls this, and how do you know what you’re eating?
A more appropriate way to think about it might be that one carrots has less carrot in it. I say that because our produce is trending towards less nutrition. For eons I had heard what sounded like an easily dismissed old-timer’s lament, “you have to eat five apples today to get the nutrition you used to get from one apple a generation ago”. That is oversimplified, but it turns out that it is often true.
The USDA has been tracking the nutrient density of 43 crops for 60 years and the trends do not look good. There are declines all over the place. As I understand it, there are two main factors: the genetic potential of each variety of produce and the realization of that potential. The good news is that we have a lot of control over both. 2 factors seem to play important roles in nutrient density:
- Plant breeding / variety selection
- Cultural practices
Here are some generalities:
- Heirloom varieties tend to have higher ND. (This doesn’t mean that we can’t create new breeds with high ND in mind).
- Foods that have been grown organically tend to have higher ND.
- Particular cultural practices can help plants live up to their genetic potential regardless of variety. These are practices we should all be supporting. More on that below.
Varieties and Breeding:
Breeders generally select for high yields, often for color, time to maturity, storage, resistance to bruising, pest, disease and drought tolerance, uniformity, ability to be harvested mechanically… pretty much anything you can think of other than nutrition. Breeding specifically for one trait often has unintended consequences for other traits like nutrition. Particularly as varieties have been selected for high yields, the roots have not been able to keep up with the tops with respect to absorbing enough nutrition from the soil. We may be able to breed a tomato plant that will yield 30 pounds, but those 30 pounds may only have the nutrition of 20 pounds of the heirlooms from which they descended. If we were to specifically test for nutrition in breeding programs, we could easily create new varieties with increasing nutrient density. Look around for heirloom varieties. They tend to have lower yields, thus more nutrition packed into a smaller package. The lower yields explain the higher prices, but perhaps they’re not really higher if you consider how much more of the standard varieties one needs to consume to get comparable nutrition.
Another important variable is cultural practices. If a particular mineral is missing from a field, it can’t end up in your food. So, a full compliment of soil minerals is critical to fostering nutrient density.
- Depending on geography, a given area may have never had certain minerals to begin with.
- Poor cultural practices and years of harvesting without remineralizing can deplete a soil.
- Furthermore, the relative ratios of minerals greatly influences their availability to plants.
A key then to good plant nutrition and high nutrient density is both mineralization and remineralization to achieve particular mineral ratios. This is referred to as the Base Cation Saturation Ratio (BCSR) theory. Many soil labs do this type of testing an offer recommendations. It’s science, but not rocket science. There’s no reason why every farm can’t maximize the genetic potential if its crops regardless of the varieties they choose to grow. This applies not only to produce, but to the pastures that raise meat as well.
At the farmers’ market, start asking farmers if they are growing their produce for nutrient density. Even if you don’t fully understand the answer, the question may prompt some investigation on their end. How many times do you think the produce manage at Whole Foods needs to get that question before they start paying attention? Agriculture is a massively polluting industry. Your food choices can overhaul agricultural practices on a national level. You’re going to eat anyway. May as well change the world in the process!