Psyllium husks (aka Ispaghula) are parts of the seeds from the plant Plantago that is native to India. Psyllium is also cultivated in other parts of the world incl. some European countries, especially countries of the former Soviet Union.
Psyllium husks are an excellent source of dietary fibre. They contain a combination of neutral and acid polysaccharides containing galacturonic acid, with a 70/30 ratio of soluble/insoluble fibre. (Ref. 1)
Dietary fibres are believed to have a whole number of health-boosting benefits - they may even help with obesity, diabetes, cancer, and cardiovascular disease. (Ref. 2)
Psyllium husks have been shown to be useful both for constipation and diarrhea - thanks to their capacity to have either gut-stimulatory or gut-inhibitory effects. (Ref. 3)
It is also interesting to note that psylliums husk can be beneficial for the management of irritable bowel syndrome (IBS). (Ref. 4) IBS is often present in people with chronic fatigue syndrome and fibromyalgia. So, we assume that if the husks can alleviate IBS symptoms, some other conditions can be alleviated to a certain degree, too.
Further studies suggest that psyllium can help with symptoms of the metabolic syndrome as well.
Metabolic syndrome is described as a set of biochemical and physical parameters which include increased central adiposity (accumulation of fat around the waist), adverse changes in blood pressure, lipid profile, and insulin sensitivity. These parameters are linked to a greater risk of developing diabetes and heart disease. One study suggested that psyllium supplementation can improve fat distribution and lipid profile. (Ref. 1)