The Top 5 Health Benefits Of Flaxseeds & How Nutritionists Use Them

If you've ever seen a field of flax, you'd probably never guess that at the base of these pretty, purple-flowered plants lie some of the world's most nutritious seeds.

Flax has been cultivated for thousands of years and, historically, has had multiple uses.

Its flowers can add color to bouquets, its fibers have long been used to make linen clothing, and its seeds can be ground into a nutritious powder. (Though it's technically possible to eat flaxseeds in their whole form, it's not the best idea. They're considered nearly impossible to digest.)

Ounce for ounce, flaxseeds are fairly expensive, especially when you compare them to other seeds—but since a serving is just 1 tablespoon, a bag is likely to last you a while.

Heart health is where flaxseeds display their greatest potential. They're one of the richest plant sources2 of the omega-3 ALA (alpha-linolenic acid), explains nutritionist Allison Gross, M.S., RDN, CDN. "Omega-3 fats have been shown to improve heart health by lowering bad cholesterol3 (LDL), raising good cholesterol4 (HDL), reducing the risk of heart arrhythmias5 (irregular heartbeat), and slowing arterial plaque buildup6, which in turn reduces the risk for heart attack and stroke," Gross notes.

Flaxseed may also offer benefits for women's health. "Some research shows that the phytoestrogens in flaxseeds, called lignans, are great for women's health because they may lower the risk of breast cancer8 in women and may even reduce tumor growth in breast cancer patients," says Gross. "This is because the lignans act as estrogen in the body."

The internet is teeming with information on flaxseeds' benefits for skin and hair—but does reality match the hype? Sort of. Though there are no human clinical trials on flaxseeds' impact on hair or skin, animal studies are promising.

"There are two small but good-quality animal studies that show benefits," says Maggie Moon, M.S., R.D., nutrition consultant and bestselling author of The MIND Diet. "A pilot study in horses found that six weeks of ground flaxseed supplementation helped heal cuts better and reduced inflammation9, all without negative side effects. And a monthlong study in dogs found that daily supplementation with flaxseed or sunflower seed temporarily improved skin and hair10 after about two weeks. When supplementation stopped, so did the benefits."

Flaxseed meal is loaded with gut-boosting fiber at almost 2 grams per tablespoon. Desiree Nielsen, R.D., the author of Eat More Plants, points out that the powder contains both soluble and insoluble fiber, each of which has benefits for digestive health.

Insoluble fiber is known for adding bulk to stool, allowing it to move through your digestive tract more quickly. Soluble fiber, on the other hand, softens stool so it's easier to pass.

Between their ample fiber content and their small dose of protein, flaxseeds have plenty to offer for weight management. A 2017 meta-analysis in Obesity Reviews found that people who regularly supplemented with flaxseed had significant reductions in body weight and waist circumference.

The answer to this one is a resounding…kind of. Because ground flaxseeds have been partially broken down, they're far easier for the body to digest—but this comes with some downsides.

"Keep in mind that because flaxseed meal has more surface area exposed, its healthy fats are being diminished since they're sensitive to oxygen and light," says Moon. She also points out that due to the grinding process, flaxseed meal contains less product per tablespoon. "You'll get more flaxseed from a tablespoon of whole flaxseed (10 grams) versus flaxseed meal (7 grams)."

Unlike pepitas or sunflower seeds, you wouldn't want to toss a handful of whole flaxseeds on a salad or into a trail mix. Again, they're largely indigestible, so you'd not only reap few health benefits from eating them this way, but you also might experience stomach upset. Stick to the ground variety for the best results.

Flaxseed oil is another form of flaxseeds available on the market. While it doesn't contain the fiber found in whole or ground flaxseeds, it does contain the beneficial omega-3 fatty acids. This form is best added to smoothies or salad dressings and is not suggested for cooking.

As for how much to eat, there's no perfect target of consumption—and you probably don't need to worry about putting too much into recipes. "Dietary consumption of flaxseeds is hard to overdo, so I wouldn't be too concerned about an upper limit," says Gross. The only caveat here is that, again, those who don't usually get a lot of dietary fiber will want to take it a tablespoon at a time.

When you buy ground flaxseed in the grocery store, you'll likely find it packaged in a bag and sitting on a shelf. But don't be fooled! The shelf of your home pantry isn't the best place to store the seeds once opened.

"Whole flaxseeds will stay fresh longer than flaxseed meal. Either way, store them in an airtight, dark, nonmetal container in the refrigerator or freezer. Your best bet is to buy them whole, store them in the freezer, and grind only what you'll consume at a time," says Moon.

Flaxseed isn't considered highly allergenic, but it's possible to have an allergy to any food. You'll know you're allergic if, after eating, you react with symptoms like hives, itching, or vomiting.

In general, most people should be able to eat flaxseeds regularly without issue, but some groups should exercise some caution.