It's ironic but true. Even though more than two thirds of Americans over the age of 20 are overweight or obese and this percentage is on the rise, at the same time many of us are undernourished. The USDA reports that a large number of adults in the US are not obtaining sufficient amounts of seven vital nutrients: calcium, magnesium, potassium, fiber, Vitamin C, Vitamin A, and Vitamin E. The good news, though, is that you don't have to spend money on fancy supplements. Here are "7 for 7" -- 7 easily obtainable, inexpensive foods that are great sources for these 7 missing dietary components.

1. Spinach: Calcium, magnesium, potassium, fiber, Vitamin C, Vitamin A, and Vitamin E ... oh my!

Leafy greens are great for your health, and spinach is packed with nutritional goodies. In fact, one cup of cooked spinach offers up a substantial amount of all seven nutrients that are commonly lacking, including close to 400 percent of your daily requirement of Vitamin A and 24 percent of the calcium you need (a nice amount of the latter for one single serving of a vegan-friendly food). It is best lightly steamed or sautéed, to reduce its oxalic acid.  

2. Beans: Calcium, potassium, magnesium, and fiber

"Beans, beans, the musical fruit ..." the kids at my school used to love to chant. And legumes such as soybeans (organic, non-GMO, if possible) and small white beans are indeed something to sing about, with abundant calcium, potassium, magnesium, and fiber. To reduce their "toot," soak your beans 8 hours or overnight before cooking, if possible. The soaking water will absorb some of the complex sugars that lead to gassiness. (I pour it onto my houseplants, which seem to digest it better than my human guests can.)

3. Buckwheat: Magnesium, potassium, and fiber

Buckwheat, despite its name, is not a form of wheat. In fact, it isn't a grain at all, but rather the seed of a flowering plant related to rhubarb, making it gluten-free and safe for people with celiac disease. What buckwheat does contain is a huge helping of magnesium -- 1 cup offers a whopping 98 percent of the required dietary allowance. It also provides 17 grams (68 percent of your RDA) of fiber, as well as 22 percent of your potassium requirements.

4. Cantaloupe: Potassium, Vitamin A, Vitamin C, and fiber

More than a colorful, refreshing appetizer -- or dessert -- cantaloupe has a high level of nutrition in proportion to its low calorie count and ease of preparation. Look to this orange-fleshed melon to replenish your stores of potassium, Vitamin A, and Vitamin C.

5. Sweet Potato: Vitamin A and C, potassium, and fiber

No need to pretty up sweet potatoes with marshmallows, canned pineapple, or even the traditional cup or two of brown sugar. This super veggie not only is full of nutrients (Vitamin A and C plus potassium) and fiber, it's also naturally sweet. Just scrub and bake, then cool for a minute or two on your tile countertop before digging in -- no added ingredients required for a delicious, creamy side dish.                                                                              

6. Low-Fat Dairy: Calcium and potassium

Low-fat dairy products, especially nonfat or low-fat yogurt and low-fat milk, are a readily available, abundant source of both calcium and potassium. Consume as is or mix them into sauces and other preparations.

7. Nuts and Seeds: Magnesium and Vitamin E

Nuts and seeds make a tasty garnish or in-between-meal food that satisfies your need for a crunch. They're not just empty calories, either, but instead supply healthy amounts of magnesium and Vitamin E. Their main drawback? A high proportion of (unsaturated) fat, so munch in moderation.

Laura Firszt writes for networx.com.