What Foods Have Lignins? Clarifying Sources and Benefits of Lignans

Did you know that flaxseed contains up to 800 times more lignans than other plant sources, but the term is often confused with a different compound called lignin? Understanding what foods have lignins, and the bioactive lignans they contain, is key to boosting your intake of these beneficial plant-based compounds.

Quick Summary

Learn the difference between lignin and lignans, and explore the top dietary sources of beneficial plant lignans, including seeds, whole grains, vegetables, and legumes for better health.

Key Points

• Clarifying the Terminology: The common term "lignins" often refers to the bioactive phytoestrogens called lignans, which have different functions from the insoluble fiber lignin.

• Flaxseed is King: Flaxseed is the richest known dietary source of beneficial plant lignans, containing concentrations significantly higher than other foods.

• Seeds are Potent Sources: After flaxseed, sesame seeds and other seeds like sunflower seeds are exceptionally high sources of lignans.

• Diverse Food Groups Provide Lignans: Whole grains, vegetables (especially cruciferous types), legumes, and berries all contribute valuable amounts of lignans to a healthy diet.

• Benefits are from Lignans: The associated health benefits, including antioxidant effects, hormonal balance, and cardiovascular support, are attributed to the lignans, not the lignin fiber.

• Absorption Requires Preparation: For maximum absorption, flaxseed must be ground before consumption, as whole seeds pass through the digestive system largely intact.

Lignins vs. Lignans: Clarifying a Common Confusion

When people ask what foods have lignins, they are most often thinking of the beneficial phytoestrogens, which are actually called lignans. While the names are similar, and they are structurally related, they are distinct compounds with different nutritional roles.

Lignins: The Insoluble Fiber

Lignins are large, insoluble polymers that form an important part of a plant's cell walls, strengthening the plant's structure and aiding in water transport. Nutritionally, lignins are components of insoluble dietary fiber, which is crucial for digestive health. Unlike lignans, lignins are not absorbed by the body but rather add bulk to stool, helping to promote regular bowel movements. Some of the best food sources of lignins are the fibrous parts of plants, such as the bran layer of cereals.

Lignans: The Bioactive Phytoestrogens

Lignans are much smaller phenolic compounds found in a variety of plants. When ingested, intestinal bacteria convert these plant lignan precursors into absorbable compounds known as mammalian lignans (enterodiol and enterolactone). These enterolignans can have weak estrogen-like effects and act as antioxidants, which have been associated with potential health benefits, including heart health and a lower risk of certain cancers.

Top Dietary Sources of Beneficial Plant Lignans

If you're seeking the health benefits associated with these phytoestrogens, focus on foods rich in lignans. The following list details the best food categories to incorporate into your diet.

Seeds: The Richest Sources

By far the most concentrated sources of lignans are seeds, with flaxseed leading the pack by a wide margin.

• Flaxseed: Unquestionably the richest source, containing 75 to 800 times more lignans than other plant sources. For the body to absorb its lignans, flaxseed must be ground before consumption.
• Sesame Seeds: Another excellent source, with a significantly higher concentration than most other foods, though notably less than flaxseed.
• Sunflower Seeds: Offer a good, moderate amount of lignans.
• Chia Seeds: A small but valuable source.

Whole Grains: A Staple for Lignans

Including whole grains in your daily diet is an effective way to increase your lignan intake, as the compounds are concentrated in the bran.

• Rye: One of the most lignan-rich whole grains.
• Barley: A versatile whole grain that provides a solid dose of lignans.
• Oats: Excellent for a healthy, lignan-rich breakfast.
• Wheat (Whole Grain): Contains lignans, particularly in the bran.
• Buckwheat: Another whole grain option with a notable lignan profile.

Vegetables: Crucial Cruciferous and Others

Many vegetables, especially those in the cruciferous family, contribute to your overall lignan consumption.

• Broccoli: Contains appreciable amounts of lignans.
• Brussels Sprouts: A hearty cruciferous vegetable with lignans.
• Cabbage: A good source, particularly white cabbage.
• Kale: Leafy green cruciferous vegetable containing lignans.
• Asparagus: A source of several different types of lignans.
• Carrots: Provide a moderate amount of lignans.
• Garlic: Known to contain lignans.

Legumes: Lignans from Beans and Soy

Legumes and soy products are a solid, reliable source of lignans.

• Soybeans/Soy Products (Tofu, Soy Milk): Well-documented sources of phytoestrogens, including lignans.
• Lentils: Offer a healthy dose of lignans alongside their other nutritional benefits.

Fruits and Berries: Sweet Sources

Many fruits and berries contain lignans, adding a sweet and delicious way to increase your intake.

• Berries: Berries like strawberries, cranberries, raspberries, and blackcurrants are good sources.
• Apricots: Contains lignans.
• Peaches: Provides a source of lignans.
• Kiwi Fruit: Contains a smaller amount of lignans.

Lignan Content Comparison in Common Foods

Food Source	Total Lignan Content (approx.)	Primary Lignans	Notes
Flaxseed	75–800 mg per 100g	Secoisolariciresinol Diglucoside (SDG)	Must be ground to absorb lignans.
Sesame Seeds	Up to 30 mg per 100g	Sesamin, Sesamolin	Excellent source, second only to flaxseed.
Rye (Whole Grain)	Up to 1891 µg per 100g dry weight	Pinoresinol, Syringaresinol	Also contains secoisolariciresinol and matairesinol.
Oats (Whole Grain)	Up to 859 µg per 100g wet basis	Pinoresinol, Syringaresinol	A good source for breakfast cereal.
Buckwheat (Whole Grain)	Up to 867 µg per 100g wet basis	Lariciresinol, Pinoresinol, Secoisolariciresinol	Another nutritious whole-grain option.
Broccoli	1325 µg per 100g wet weight	Varied, includes matairesinol, secoisolariciresinol, lariciresinol, pinoresinol	High vegetable source, part of the cruciferous family.
Cranberries	136 µg per 100g	Secoisolariciresinol	Good source of lignans among fruits.

*Values vary by cultivar, processing, and growing conditions. Table data is based on selected studies cited in search results.

Why Consume Lignans? Health Benefits

The health benefits of lignans are linked to their role as antioxidants and phytoestrogens after being converted by gut bacteria. Some potential benefits include:

• Antioxidant Effects: Lignans act as potent antioxidants, helping to protect cells from damage caused by free radicals. This can help to mitigate oxidative stress and reduce the risk of chronic diseases.
• Hormonal Balance: The phytoestrogen nature of lignans allows them to weakly bind to estrogen receptors in the body. This can help to balance hormonal activity, especially during menopause, potentially reducing symptoms like hot flashes. In cases of excess estrogen, they can also have a balancing, weaker effect.
• Cardiovascular Health: Studies have suggested that diets rich in lignans, particularly from sources like flaxseed, may help improve cholesterol levels and reduce the risk of cardiovascular disease. Lignans can help to reduce total cholesterol and LDL ('bad') cholesterol by binding to bile acids.
• Potential Cancer Risk Reduction: The antioxidative and hormone-balancing properties of lignans have been associated with a potential reduced risk of certain hormone-sensitive cancers, including breast, uterine, and prostate cancers.

Conclusion: Embracing a Lignan-Rich Diet

While the term 'lignins' refers to insoluble plant fiber that benefits digestion, the bioactive, health-promoting compounds most people are interested in are called 'lignans.' The best way to increase your intake of these beneficial phytoestrogens is by incorporating a diverse range of plant-based foods into your diet. By focusing on rich sources like ground flaxseed and sesame seeds, alongside whole grains, a variety of vegetables, legumes, and berries, you can reap the antioxidant and hormone-modulating benefits. A balanced diet featuring these foods provides a holistic approach to wellness, offering not only lignans but also a spectrum of other essential nutrients and fiber crucial for overall health. To truly boost your lignan intake, consider adding a tablespoon or two of freshly ground flaxseed to your meals each day. Linus Pauling Institute

Frequently Asked Questions

What is the primary difference between lignans and lignins?

Lignans are small phenolic compounds with weak estrogen-like and antioxidant properties, converted by gut bacteria for absorption. Lignins, on the other hand, are large, insoluble polymers that function as a form of dietary fiber and are not absorbed by the body.

Why are flaxseeds such an exceptionally rich source of lignans?

Flaxseeds contain a high concentration of the lignan precursor secoisolariciresinol diglucoside (SDG), providing anywhere from 75 to 800 times more lignans than most other plant sources.

Are lignans from food absorbed directly by the body?

No, dietary lignan precursors must first be converted into absorbable mammalian lignans (enterodiol and enterolactone) by intestinal bacteria. This process is essential for their bioavailability.

Does eating whole or ground flaxseeds make a difference for lignan intake?

Yes, eating ground flaxseeds is highly recommended. The lignans are located inside the fibrous seed, and grinding breaks down this tough outer layer, allowing for proper absorption by your digestive system.

What are some good vegetable sources of lignans?

Many vegetables contain lignans, with particularly notable sources including cruciferous vegetables like broccoli, cabbage, Brussels sprouts, and kale, as well as carrots and asparagus.

Do oils from lignan-rich seeds like flax and sesame contain lignans?

No, lignans are not present in the oil fraction of seeds. Therefore, flaxseed oil or sesame oil typically does not contain lignans unless ground seeds have been added back into the product.

Are there health benefits to consuming lignin, the insoluble fiber?

Yes, while different from lignans, lignin is a form of insoluble fiber that plays a vital role in digestive health by adding bulk to stool, promoting regularity, and preventing constipation.