6 Surprising Nutritional Powerhouses

Think citrus fruits are the leading source of vitamin C? These sleeper hits of the nutrition world will make you reconsider your next bite.

1. Red Pepper
If you want to boost your vitamin C by stocking up on citrus fruits, you're on the right track: A medium orange has 70 mg of vitamin C, just 5 g shy of your daily quota. But - surprise! - 1/2 cup of red pepper boasts even more: 95 mg.

Bonus: 1/2 cup cooked broccoli has 51 mg of Vitamin C, more than two-thirds your daily quota.

Related: Healthy-Eating Lessons to Steal from Vegetarians

2. Artichoke
A diet high in fiber helps you maintain a healthy weight and lowers your risk of diabetes and heart disease. Women under 50 should eat 25 grams of fiber a day, and those over 50 should get 21 grams. A cup of instant oatmeal has 4 g, and 1/2 cup of beans can pack more than 7 g. But artichokes have them beat: A medium one packs 10.3 g of the good stuff.

Bonus: Lesser-known fiber superstars are raspberries (8 g per cup) and pears (5.5 g for a medium one).

3. Extra Firm Tofu
Think you need to be a carnivore to get enough protein? Think again. A serving of deli-style turkey breast has 5.6 g of protein - about 1/8 of the 46 grams adult women need daily. But a serving of extra-firm tofu has a whopping 9 g.

Bonus: 1/2 cup of kidney beans has 6.7 g protein and 1/2 cup of cooked quinoa has about 4 g.

Related: 15 Tasty Ways to Eat More Whole Grains

4. Salmon
Vitamin D can be tough to get from food, but that doesn't mean you can't find it in the grocery store. A cup of vitamin D-fortified orange juice has 154 IUs (the international unit by which the sunshine vitamin is measured), or 39 percent of the DV. (Many health experts advise getting more than recommended amounts.) But 3 ounces of salmon has nearly triple that amount: 447 IUs, or 112 percent of the DV.

Bonus: Eggs are another source of vitamin D, with 41 IUs each. Just don't toss the yolks - that's the part containing the vitamin.

5. Sardines
Dairy foods like milk and yogurt are popular go-to sources of calcium. And for good reason: 8 ounces of plain, low-fat yogurt has 415 mg, or 42 percent of the DV, while a cup of nonfat milk has 299 mg (30 percent of DV). But dairy isn't the only source of this bone-strengthening mineral. Three ounces of sardines canned in oil (with bones) packs 325 mg of calcium (more than a cup of milk!).

Bonus: 1 cup of raw, chopped kale has 100 mg of calcium and 1/4 cup of almonds has 96 mg.

Related: Snack Time! 7 Guilt-Free Foods You Should Munch

6. White Potato
If you've ever had a painful leg cramp, someone may have suggested eating a banana to boost your potassium levels. (The recommended dietary intake is 4.7 g per day, and low amounts of the mineral can lead to muscle cramping). But bananas aren't the only potassium-rich food in the produce aisle. A medium banana has 422 mg, but a medium white potato has more than double: 897 mg!

Bonus: 1 cup of carrot juice has 689 mg. Drink up!

-By Marnie Soman

More from Good Housekeeping:
15 Slimming Superfoods You Should Be Eating
The Truth Behind 9 Popular Vitamins and Supplements
12 Ways to Cut Calories Without Sacrificing Flavor