Flaxseed (Linum usitatissimum L.) is a nutritional powerhouse rich in alpha-linolenic acid (omega-3 fatty acid), lignans (especially secoisolariciresinol diglucoside), and dietary fiber. These bioactive components possess anti-oxidant, anti-inflammatory, and lipid-modulating properties, suggesting potential health benefits for humans and animals. This review explores the effects of flaxseed consumption or its isolated bioactive ingredients on various health conditions. We delve into existing research on the potential impact of flaxseed on cardiovascular health, cancer, gut health, brain function, and hormonal balance in menopausal women. The review highlights the unique composition of flaxseed, including its high content of alpha-linolenic acid (over 70% of total oil), protein (20–30%), and dietary fibre (28%). Flaxseed also has the highest lignan concentration among plant sources. This distinct chemical profile positions flaxseed as a promising candidate for exploring its preventive and functional properties. The review emphasises the well-established safety of flaxseed under proper storage and processing conditions.