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Food is supposed to do more than simply satisfy your hunger; it is supposed to provide your body with the nutrients it needs to function. Good food does this, but as most people in this country continue to be overfed and undernourished, and as we find that the chronic diseases that bedevil society have their origins in poor health and nutrition, it seems that good food is getting harder to come by. However, there are many steps that can be taken to improve the nutritional content of the produce you grow to feed your family. These steps do not occur at just one point in your “food chain.” From plot to pot, here are some ways to provide a nutritional boost to your plate.
Building healthy soils
Nutritious foods begin with healthy soils for a couple of reasons. Many antioxidants that humans want to consume are produced by plants in greater amounts if they are growing in nurturing conditions. If a plant is struggling to survive, it is using its energy to provide for its basic needs and will not be producing as much of the anthocyanins, lycopene, lutein, and numerous other protective phytonutrients that benefit both the plant itself and us. People also require minerals for health; these need to be present in the soil in order to be taken up by plants and thus be made available to humans.
So what makes a healthy soil? Soil microbes play a critical part. They are a biological component that works with the physical components of soil to create overall soil health.
Carbon compounds in their many stages of composition (and decomposition) are also essential. Carbon is the core building block of plant life and also of soil biology. Dan Kittredge of the Bionutrient Food Association (an organization whose objective is to increase quality in the food supply) advocates not only providing soils with minerals, microbes, and carbon sources, but also aiding them in maintaining the necessary levels of air and water.
Providing and maintaining each of these soil components become so interrelated that it can be hard to separate one from the other – humic substances increase a soil’s water-holding capacity, which encourages plants to grow well, which causes them to send exudates into the soil, which causes the soil microbes to proliferate, which further increases the soil’s water-holding capacity and mineral levels, and on and on.
Plants are an integral part of the soil ecosystem. Remember that various plants should be continually growing in your soil, whether cash crops or cover crops.
Selecting healthy plants
Now it’s time to plant. Let’s start with some basic information. Cucumbers, summer squash and zucchini, green beans, and fresh peas have little nutrition. They do have some; all fresh produce at least has some vitamin C. But when matched against a number of other fruits and vegetables that are simply loaded with nutrition, they have relatively little by comparison.
On the other hand, garlic, red cabbage, red pepper, kale, and beets have loads of nutrition. So an initial thought might be to adjust your planting selections with the intention of altering your menu. This does not guarantee that you will eat any healthier, as you could simply decide not to eat these “strange and foreign vegetables” in the end. However, if children are more apt to try eating different vegetables when they are involved in the cooking of them, maybe parents would be equally willing if they grew them.
But if you love cucumbers, don’t remove them from your diet or garden. Rather, be mindful about how you consume them. Instead of making cucumber salad with three cups of cucumber, maybe you can start to eat more green salads with a “healthy” topping of cucumber instead.
It is not always a question of produce selection. In many cases, increased nutrition can be achieved (more painlessly) by variety selection. For example, purple carrots contain anthocyanins, which orange carrots lack, in addition to high amounts of beta and alpha carotene. The Purple Peruvian potato has anthocyanins as well, and because of this, it is much more nutritious than white-fleshed and white-skinned potatoes. This is one of the basics in food nutrition: the deeper and darker the color of a vegetable (or fruit), the more nutrition it will have, and the purples, reds, and greens (the darker the better in each case) are superior to yellows and whites. So select sweet corn that is blue, red, or at least a deep yellow in color. Grow those tomatoes that are deep red, purple, or even described as black or brown. Choose the purple carrots and potatoes.
A second rule for increased nutrition is that, in general, the smaller a specific fruit or vegetable is, the more nutritious it is. A currant or cherry tomato has more nutrition than a beefsteak-style, large tomato. A pearl onion has more nutrition than one of those one-pounders.
The reason size matters is that many nutritional components (the antioxidant type) are concentrated in the skin and outer layers of produce, so the more skin you eat, the better. To approach this another way, for a set volume of a food, such as tomatoes, you need to maximize the amount of skin you are going to eat. Two cups of diced tomato from large tomatoes is going to include much less skin than two cups of sliced cherry tomatoes.
This is somewhat related to the third principle, which is that the more open the structure of a vegetable is, the more nutrition it should have due to exposure to the sun, which stimulates the production of phytochemicals. Phytochemicals mean nutrition for you. Selecting for exposure to the sun should lead you to looseleaf heads or leaf lettuce as opposed to tight heads of lettuce, and looseleaf radicchio instead of a firm head of radicchio.
Certain varieties of many kinds of crops are also genetically disposed to being more nutritious than other varieties. The Ovation strawberry has two times more antioxidants than most other strawberry varieties. Packman broccoli is extra nutritious, as is Jersey Knight asparagus. Reading variety descriptions can help to identify these powerhouses.
Additionally, Dan Kittredge recommends selecting any variety specifically mentioned as being valued for its flavor. Flavor comes from nutrition, so any time flavor is mentioned, the variety intrinsically has a greater potential to produce nutritious food. It is important to note that the nutrition a plant is described as having is its genetic potential. If a growing plant is showing signs of nutrient deficiency, the potential of the crop is now limited, and it will not be as nutritious as it could have been.
Cultivation techniques also impact the nutritional levels of plants. Many practices here overlap with maintaining healthy soils.
Plants (and soils) need water and air, so maintaining moisture levels in the soil is important, of course. This may take the form of planting into raised rows or beds so that moisture drains properly from the root zone. It could include mulching the soil (or planting a cover crop) to hold in moisture and to protect the soil surface from weathering.
Note that too much water is as much of a problem as too little. It forces air out of the soil, and produce from plants that have been receiving more than the ideal amount of water do not have as intense a flavor; the taste is “watered down,” and good flavor goes a long way toward encouraging willing consumption. Good cultivation practices also mean not working the soil when it is too wet, which will lead to the destruction of soil pores used by both air and water.
As mentioned above, sunlight touching plant surfaces stimulates the plant into producing protective compounds that add to their nutritional content. This is why an apple on a sunny portion of a tree will be more nutritious than one grown in a shady portion. So while apples, pears, peppers, and tomatoes may need some protection from the sun via their plant’s leaves, growing underneath too dense a canopy would mean too little sunlight and therefore a loss of nutrition. Likewise, it is possible for a crop to spend too much time underneath a shade cloth, reducing its nutritional performance.
Before we get to post-harvest handling, a word on harvesting itself. Not only are many fruits and vegetables at the peak of flavor when they are at the peak of ripeness, but this is also when they are at the peak of nutrition. Some crops, such as tomatoes, apples, and peaches, give you a little leeway and continue to ripen after harvesting. However, berries, cherries, and grapes do not ripen after harvest. So if you are harvesting for immediate family use, allow your foods to be as ripe as possible.
While on the subject of ripeness, make sure that if you grow winter squash, you learn how to test for their ripeness accurately so that you only harvest them when they are fully ripe. Though the difference may not be as stark as with ripe and not-fully-ripe strawberries, for example, a fully mature butternut squash is more flavorful and also more nutritious than one that was harvested too early.
At this point, you may be asking yourself about the difference between green bell peppers and those of other colors. A green bell pepper is immature (there are some peppers whose immature color is a white or purple, but shades of green are most prevalent). Does that mean that once it has ripened and is fully mature (typically red, orange, or yellow), it, too, is more nutritious? Yes, it most certainly does. In fact, the red bell pepper is one of the most antioxidant-rich vegetables there is; the green pepper is nowhere in the running.
Anyone who raises produce for sale is familiar with this concept. The way you harvest and handle your crops has a huge impact on their appearance and, therefore, sell-ability.
But harvesting impacts nutrient levels at the same time. A harvested crop is not a dead crop. It is alive and “breathing,” or respiring. This means it is consuming oxygen and producing carbon dioxide. The process breaks down carbohydrates and organic acids in the plant to release energy, and compounds that affect nutritional value are lost. Respiration is slowed by lower temperatures. That’s a key reason why cooling off crops as quickly as possible is so important for nutrient retention.
Harvest early in the morning so that your crops have been naturally cooled by the night air. Do not let harvested crops sit in the sun. You must get your produce into the cooler as quickly as possible.
But before that, there is washing to consider. If you have picked a cool crop and it really isn’t that dirty, just get it right into the refrigerator. If it is dirty, clean it and drain it thoroughly, as excess moisture creates the perfect environment for decay; just don’t forget about it and leave it out too long.
An important thing to remember is that if you are harvesting a crop that isn’t already cool, let it soak in water for a time, whether it is dirty or not. View this not as a cleaning step but rather as a cooling-off step, as the water will bring down its temperature much more quickly than simply refrigerating it will.
Ideal post-harvest handling means more than just rapid cooling; other steps can be taken, especially when the harvest is for personal consumption and not for sale. Remove the tops from root crops such as carrots and beets. Leaving them on during storage increases respiration and nutrient loss. In some cases, just using the produce as soon as possible (no storage at all) is the best way to prevent the loss of nutrition. Spinach that has been stored for one week will have lost half of its antioxidants, and lettuce should not be stored for extended periods either. However, proper post-harvest handling and storage in closed plastic bags with pinprick-size holes to allow for respiration will help to maintain quality for as long as possible.
Preparing “health food”
We are now at the final link in the chain, and it is time to prepare your produce to eat.
Fast Food: Different elements come into play for nutrient retention when we talk about food preparation. The first is how quickly produce is used after harvesting. For some crops, this is a critically important issue, and for others, not so much. Remember the respiration rate we talked about earlier? This is where it becomes very important.
As you might expect, some crops have high respiration rates and some have low ones. A low rate means that the crop can be harvested and held; it is a good storage crop that will not have lost much of its nutrient content before you consume it. Cabbages, beets, and carrots are this sort of vegetable. Even cauliflower can be stored for roughly a week with negligible nutrient loss.
Vegetables that have a high respiration rate lose much of their stored nutrients promptly and are best eaten very fresh. Broccoli and Brussels sprouts, two vegetables with some of the highest antioxidant levels, are very prone to losing nutrition and sweetness in storage, due to respiration. Asparagus is much the same.
Skin Is In (and More): How food is prepared, above and beyond the cooking method, can influence its ultimate nutritional content as well.
As discussed above, vegetables and fruits have their greatest nutrition in and below their skin or peel. This holds true for foods you would never think of peeling or can’t peel (celery and strawberries, for example), as well as ones that often are peeled. The latter group is large and includes apples, carrots, cucumbers, peaches, pears, potatoes, etc. Potatoes, for example, have 50% of their antioxidant content in their skin. Whenever possible, you should leave the skin on your foods.
Another example of the importance of preparation relates to garlic. Garlic is by far the most effective cancer-fighting component of your diet, thanks chiefly to its allicin content. However, whether or not you reap its substantial benefits depends largely on how you prepare it for cooking – this is a question of time, as explained in the inset box below.
No details in food preparation and its impact on nutrition are more fascinating than those surrounding garlic and its allicin levels.
Allicin is a phytochemical (specifically, a thiosulfinate) and garlic’s most active ingredient, earning it the distinction of being the food which is by far the strongest inhibitor of tumor cell growth. Amazingly, an intact clove of garlic doesn’t contain any allicin! Rather, it contains alliin (an amino acid derivative) and alliinase (an enzyme). These compounds are stored separately, compartmentalized within garlic. When garlic is minced, crushed, or chewed, the elements mingle and create the allicin.
However, alliinase is heat sensitive. If you were to mince garlic and then apply heat to it by immediately placing it into a hot pot or pan, the allicin-producing reaction would fail to take place, and you would lose a lot of potential nutrition.
To preserve the cancer-fighting ability of your garlic, then, it is necessary to mince or crush it (the finer the better, as the more the garlic cells are broken down, the more the alliin and alliinase will mingle and the more allicin will be produced). Then allow it to sit for 10 minutes before you put it in a heated environment. Note that if you are using garlic in a cold dish, you don’t have to worry about the 10-minute preparation interval.
You don’t have to consume garlic raw – once the allicin is formed, it is relatively heat stable. But don’t expose the enzyme alliinase to heat before it has had time to do its job.
No food you can eat has greater cancer-fighting capabilities than garlic – but only when properly prepared.
Freezing, which is often a preparation step on the road to a finished dish, has nutritional effects of its own. Some foods lose so much nutrition when they are frozen that this method of preservation should be avoided. Broccoli, carrots, cauliflower, and Brussels sprouts are good examples. On the other hand, blueberries and raspberries possess almost as much nutrition when frozen as when fresh. You can conserve more nutrients when you freeze items as quickly as possible (both in terms of how soon you freeze them after harvesting and how rapidly the food actually freezes).
In Hot Water: Lastly, deciding how you will ultimately cook (or not cook) your food is your final opportunity to get the most nutrition out of it. In addition to avoiding nutrient loss, if you play your cards right, you will be able to increase nutrient availability as well.
Some foods, such as arugula and kale, are most nutritious when eaten raw. Many foods, however, benefit from light cooking, such as sautéing, because the heat makes some nutrients (such as lycopene and carotenoids) more bioavailable (it converts them to a form more accessible to the body). This group includes asparagus, beets, carrots, and tomatoes. Many foods also benefit from being cooked with fat, since fat-soluble vitamins (A, D, E, K) are more bioavailable in its presence. Boiling is consistently the worst way to prepare vegetables in terms of nutrient loss, and is especially harmful to arugula, beets, broccoli, carrots, and cauliflower.
Now that you have all of this information, it is time to get active and creative. Trade a low-nutrition tomato variety for a high-nutrition one. Make your favorite recipes “potato-skin friendly.” Look for cooking options that will allow you to swap high-nutrition food in. For example, if you want onion on your sandwich, you would benefit greatly from using red or yellow (cooking) onions that are much more nutritious than sweet white onions—but you must sauté or caramelize them first to remove their assertive heat. This is doubly beneficial, as this method of cooking may itself increase the amount of the antioxidant quercetin in the onions.
Knowledge is power – in this case, the power to improve the nutrition in your food.
Many nutritious foods do not have mild flavors, but aggressive ones. Others have reputations of plain unpalatability. Though most people begin to crave nutritious produce as their diets (and tastes) evolve, it may help to use some “tricks” to make foods more acceptable in the beginning.The recommendations below can help with many “offenders,” from arugula and kale to beets and their greens to Brussels sprouts:
• Garlic, horseradish, and mustard (stoneground or Dijon): These additions have powerful yet desirable flavors that can help to mask other tastes, replacing one aggressive flavor with another.
• Dried fruits and honey (or other natural sweetener): These can take the edge off bold tastes and provide a touch of sweetness, and only a little is needed for them to have an effect.
• Citrus zests (lemon, lime, orange): Zests give a pleasant tang to food, often adding a whole new dimension to a vegetable dish.
• Toasted nuts or nut butters (you pick the nut): Whether whole or “buttered,” only a small amount is required for the richness and full flavor of nuts to become prominent and counteract bitterness.
• Herbs and spices: Herbs like basil, thyme, and summer savory, and spice mixtures like curries and masalas contribute heavily to the flavor of dishes; the spices, in particular, are often the dominant note. Include healthy vegetables, but let another flavor take the lead on occasion.
• Avoid boiling vegetables: Boiling tends to remove both nutrients and flavor (and even texture) from produce; roasting vegetables, especially with a touch of olive oil and salt, can do the opposite.
• Partner up the strong with the mild: Combining the familiar, mild, or perhaps even mundane with the especially healthy and harrowing is a great way to make some dishes healthy and more acceptable to all in the family. Irish potatoes, noodles, and cheese are frequently used as helpers in this way.
• Just a little advanced help: It may sound silly, but chefs say that making vegetables bite-size, particularly when feeding children, can garner dishes greater acceptance; the vegetable is remembered not as “a lot of chewing” but rather as being just right. This is probably a good place to mention guarding against undercooking and overcooking vegetables as well. Texture counts.
An earlier version of this article, titled “Growing for Nutrition,” appeared in the September 2020 issue of Acres U.S.A. (www.acresusa.com).
Photos courtesy of Leah Smith.
About the Author
Leah Smith is a freelance writer and home and market gardener. She works on her family’s farm in mid-Michigan called Nodding Thistle (certified organic 1984-2009, principally by Organic Growers of Michigan). Leah has learned a great deal of information about plant variety selection and food preparation for increased nutrition from the work of Jo Robinson and her book Eating on the Wild Side. A graduate of Michigan State University, she can be reached at [email protected]
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Published in the Price-Pottenger Journal of Health and Healing
Spring 2021 | Volume 45, Number 1
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