Flax (Linum usitatissimum) is one of the oldest cultivated crops, dating back thousands of years to ancient Egypt and Mesopotamia. Originally grown for its fiber, which is used to make linen, flax also gained prominence for its nutrient-rich seeds, known as flaxseeds or linseeds. Native to the Mediterranean region, flax is now cultivated in temperate climates worldwide, with Canada, Russia, and China leading global production. While flax fiber remains valuable for textiles, flaxseeds have become a popular dietary component due to their nutritional content and health benefits.
Plant information about Flax
Flaxseeds are small, golden-yellow-light brown seeds consumed whole, ground, or oil. Known for its mild, nutty flavor, flax complements many foods and is an easy addition to many diets. They are commonly added to cereals, smoothies, and baked goods and are frequently used as a vegan egg substitute in recipes. Flaxseed oil is pressed from the seeds and used in culinary and health applications. For centuries, flaxseed has been utilized in various aspects of daily life, including as a drying oil in painting and varnishing and for medical purposes such as managing respiratory disorders, constipation, abdominal discomfort, urinary tract infections, and skin inflammation. The seeds typically yield 35–45% oil, composed of approximately 9–10% saturated fatty acids (palmitic and stearic acids), about 20% monounsaturated fatty acids (primarily oleic acid), and over 70% α-linolenic acid. Flaxseed contains 20–30% protein, with dietary fiber content reaching up to 28%.
The composition of flaxseed oil varies depending on factors like seed cultivar, growing location, environmental conditions, and analytical methods. Known for its impressive health benefits, flaxseed oil is one of the richest plant-based sources of polyunsaturated omega-3 fatty acids, particularly linoleic and α-linolenic acids. These fatty acids undergo metabolic conversion through desaturation and elongation into 20-carbon derivatives, contributing to their nutritional significance.
Is flax oil suitable for edible applications?
The direct use of unprocessed flax oil in the human diet is constrained due to its instability. Flax oil, rich in alpha-linolenic acid (ALA), is prone to oxidation and polymerization, which, while beneficial for industrial purposes, limit its suitability as a substitute for oils like canola or corn. To address these limitations, researchers have focused on modifying the fatty acid composition of oils such as soybean and canola to enhance their ALA content, aiming to replicate flax oil’s health benefits and replace fish oils in diets. Efforts to improve the stability of flax oil for food applications led to the development of cultivars with significantly reduced ALA levels (1–3%). These low-ALA flax variants, referred to as "Solin" by the Flax Council of Canada, are suitable for edible oil production but offer fewer health benefits due to the reduced ALA content. Additionally, flax oil presents opportunities for use in products like margarine and cocoa butter replacements, though these applications further diminish its nutritional value.
Is flaxseed consumption always beneficial?
Flaxseed offers numerous bioactive components like alpha-linolenic acid (ALA), lignans, and fiber, available in various forms such as whole seeds, ground flaxseed, flaxseed oil, and flax milk. Flax milk, a newer addition, combines finely milled flaxseed with water, offering a lactose-free, cholesterol-free alternative to dairy and other plant-based milks, suitable for individuals with soy, nut, or gluten allergies. Despite its benefits, flaxseed faces challenges regarding flavor and stability. Its high ALA content is prone to oxidation, leading to rancidity and bitterness. However, its natural antioxidants, like secoisolariciresinol diglucoside (SDG), can minimize these effects. Flaxseed into baked goods, like muffins and breads, preserves ALA even at high baking temperatures and disguises bitterness through flavoring such as cinnamon or banana. Flaxseed processing influences its stability and bioavailability. Milling enhances nutrient absorption but exposes ALA to oxidation, mitigated by cooler storage. Although flaxseed contains compounds like phytic acid and cyanogenic glycosides, studies suggest these do not adversely affect human health at typical dietary levels. Advances in plant breeding and food processing may further address these concerns.
Nutritional Value of Flax
According to the USDA, a 100-gram serving of whole flaxseeds provides approximately:
- Water: 7.0 g
- Energy: 534 kcal
- Protein: 18.3 g
- Carbohydrates: 28.9 g
- Total fat: 42.2 g
- Dietary fiber: 27.3 g
- Sugars: 1.6 g
- Calcium: 255 mg
- Iron: 5.7 mg
- Magnesium: 392 mg
- Phosphorus: 642 mg
- Potassium: 813 mg
- Sodium: 30 mg
- Zinc: 4.3 mg
- Vitamin B6: 0.6 mg (30% RDI)
- Folate: 87 µg (22% RDI)
Flaxseeds are notably high in dietary fiber, plant-based omega-3 fatty acids, and essential minerals, making them a nutrient-dense food. Their high fiber and healthy fat content provide significant health benefits, particularly for heart and digestive health.
Health Benefits of Flax
Rich in fiber, omega-3 fatty acids, and lignans (plant compounds with antioxidant properties), flaxseeds have numerous positive effects on overall health.
Support for Heart Health: Flaxseeds are particularly known for their alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid linked to improved heart health. ALA may help reduce the risk of heart disease by lowering blood pressure and reducing inflammation. Additionally, the fiber and lignans in flaxseeds may contribute to heart health by helping to lower cholesterol levels and improve blood vessel function.
Promotion of Digestive Health: Flaxseeds' high fiber content, including soluble and insoluble fiber, promotes digestive health by supporting regular bowel movements and enhancing gut function. Soluble fiber in flax absorbs water, forming a gel-like substance that can aid digestion, while insoluble fiber adds bulk, which may help prevent constipation. This combination supports a healthy digestive system and may positively influence gut bacteria.
Support for Skin and Hair Health: Flaxseed oil, rich in ALA and other omega-3 fatty acids, is often used to promote healthy skin and hair. These essential fats contribute to skin hydration, elasticity, and overall resilience. Additionally, omega-3s may help reduce inflammation in the skin, making flaxseed oil beneficial for those with dry or sensitive skin.
Regulation of Blood Sugar Levels: Flaxseeds may help regulate blood sugar due to their high fiber content, which slows the absorption of glucose into the bloodstream. This effect may benefit individuals managing diabetes or those seeking stable blood sugar levels. The lignans and antioxidants in flax also contribute to metabolic health, making flax a valuable addition to a balanced diet.
Potential Cancer-Preventive Properties: Flaxseeds are one of the richest sources of lignans with antioxidant and estrogen-like properties. These compounds may help reduce the risk of hormone-related cancers, such as breast and prostate cancer. While more research is needed, preliminary studies suggest that flax may contribute to a lower risk of certain types of cancer due to its high lignan content.
References
https://www.mdpi.com/2227-7382/11/4/37
https://pmc.ncbi.nlm.nih.gov/articles/PMC6630319/
https://fdc.nal.usda.gov/fdc-app.html#/food-details/1100610/nutrients
