Nuts have a lot going for them. They're nutritious, portable and delicious. It’s no wonder they're such popular snacks, especially among those who eat for better health. Because they are naturally gluten- and grain-free, they can be snack for those with common food allergies — though not someone with a nut allergy, of course.

A serving of nuts a day has been linked to longer life and a lower risk of long-term weight gain. Eating nuts instead of carbs aids in controlling diabetes because of the nuts' protein and good fat content along with low carbohydrate content. In fact, a more recent study published in the journal BMJ Nutrition, Prevention & Health, researchers suggest that simply by substituting a half serving of nuts for unhealthy foods — think processed meats, French fries and potato chips — is a simple strategy to ward off the gradual weight gain that often accompanies the aging process. (They looked at the eating habits of 175,000 men and women over 20 years, so no small potatoes.) Nuts may also be good for your heart, says the Mayo Clinic, because they are thought to lower LDL cholesterol levels — that's the "bad" kind.

Those benefits and more are why nuts are also included on many healthiest foods lists.

Generally speaking, nuts are a great source of protein, healthy fats, and a moderate source of carbohydrates. But each has its own benefits as well. Here are some of the most popular nuts on the market and the nutritional values of each.

Raw almonds in a bowl Almonds are a great source of protein especially for those looking for meat-free ways to get their daily dose. (Photo: vanillaechoes/Shutterstock)

Almonds: Almonds are one of the most popular nuts for good reason. They're mild in taste, a more frugal nut choice and easy to find. For those who need a peanut-free nut butter option, almond is the most popular and is widely available. Almonds are higher in protein and fiber in comparison to other nuts, and have been found in preliminary studies to be a heart-healthy snack.

1 ounce of almonds will give you the following percentage of daily nutrient needs:

  • 12 percent of protein
  • 14 percent of fiber
  • 17 percent vitamin B2
  • 19 percent of magnesium
  • 32 percent of manganese
  • 37 percent of vitamin E

Walnuts: Walnuts are another popular nut and are often added to granola, baked goods or fruit salads. Interestingly, the phenols of the walnuts are mostly in the skin of the walnuts. Phenols are believed to have an anticancer effect, so keeping the skin on walnuts may be beneficial. They are also a great source of vitamin E and omega-3 fatty acids.

1 ounce of walnuts will give you the following percentage of daily nutrient needs:

  • 8 percent of fiber
  • 9 percent of protein
  • 10 percent phosphorus
  • 11 percent of magnesium
  • 22 percent of copper
  • 48 percent of manganese

Hazelnuts (also known as filberts): These are a personal favorite because they're full of flavor and grown locally in Oregon. Of the tree nuts, hazelnuts have the highest amount of folate per serving, making them an excellent nut to consume during pregnancy. For older adults, eating hazelnuts daily can increase vitamin E and magnesium levels while also decreasing LDL and total HDL cholesterol.

1 ounce of hazelnuts will give you the following percentage of daily nutrient needs:

  • 8 percent of vitamin B6
  • 8 percent of protein
  • 12 percent of thiamin
  • 12 percent of magnesium
  • 21 percent of vitamin E
  • 24 percent of copper
  • 87 percent of manganese

pistachios It may seem counterintuitive, but pistachios can help you lose weight. (Photo: Handmade Pictures/Shutterstock)

Pistachios: These lovely nuts owe their bright green color to their chlorophyll content, and they're delicious eaten shelled and in a variety of desserts. When buying in shell, look for ones that aren't closed all the way. Not only will the ones with shells slightly parted be easier to open, but the closed shells also indicate immature nuts.

1 ounce of pistachios will give you the following percentage of daily nutrient needs:

  • 12 percent of protein
  • 12 percent of fiber
  • 14 percent of phosphorus
  • 16 percent thiamin
  • 18 percent of vitamin B6
  • 18 percent of manganese

Pecans: A wonderfully sweet nut, pecans are used in many traditional Southern desserts with delicious results. Growing up, pecan pie was my favorite Thanksgiving dessert. Pecans have a richer taste due to a higher fat content, which is why they're so dessert-worthy.

1 ounce of pecans will give you the following percentage of daily nutrient needs:

  • 5 percent of protein
  • 8 percent of magnesium
  • 8 percent of phosphorus
  • 11 percent of fiber
  • 12 percent of thiamin
  • 63 percent of manganese

Editor's note: This article has been updated since it was originally published in June 2014.

What's so healthy about nuts?
Take a look at the nutritional benefits of 5 popular tree nuts, and you'll realize nuts are a great snack!