Cannabis sativa L
. is an annual plant in the Cannabaceae family. It has been an important source of food, fiber, medicine and psychoactive/religious drug since prehistoric times [1
is mentioned as a medication in ancient Egyptian medical texts: Ramesseum III Papyrus (1700 B.C.), Eber's Papyrus (1600 B.C.), the Berlin Papyrus (1300 B.C.), and the Chester Beatty VI Papyrus (1300 B.C.) [1
Two main types of Cannabis Sativa L. must be distinguished, the drug and non-drug types. The first is also known as marijuana, hashish or Cannabis tincture and contains Δ9
-Tetrahydrocannabinol (THC) in concentrations between 1-20%, high enough to exhibit psychoactivity. The second type of Cannabis Sativa L
. is industrial hemp with THC concentrations < 0.3% so it has no psychoactive properties [3
Canada, Australia, Austria, China, Great Britain, France and Spain are among the most important agricultural producers of hempseed. In the United States, it is not legal to cultivate hempseed. This is primarily because many believe that by legalizing hemp they may lead to a legalization of marijuana [5
]. Other governments have accepted the distinction between the two types of Cannabis and, while continuing to penalize the growing of marijuana, have legalized the growing of industrial hemp [5
Hempseed possesses excellent nutritional value. It is very rich in essential fatty acids (EFAs) and other polyunsaturated fatty acids (PUFAs). It has almost as much protein as soybean and is also rich in Vitamin E and minerals such as phosphorus, potassium, sodium, magnesium, sulfur, calcium, iron, and zinc [6
]. The nutrient profile of hempseed is shown in Table . Hempseed oil contains all of the essential amino acids and also contains surprisingly high levels of the amino acid arginine, a metabolic precursor for the production of nitric oxide (NO), a molecule now recognized as a pivotal signaling messenger in the cardiovascular system that participates in the control of hemostasis, fibrinolysis, platelet and leukocyte interactions with the arterial wall, regulation of vascular tone, proliferation of vascular smooth muscle cells, and homeostasis of blood pressure [8
]. In a study that included 13 401 participants, 25 years and older from the Third National Health Nutrition and Examination Survey, an independent relationship was shown between the dietary intake of L-arginine and levels of C-Reactive protein [9
], a marker strongly correlated with the risk of cardiovascular disease (CVD) [10
]. The results of this populated-based study suggested that individuals may be able to decrease their risk for CVD by following a diet that is high in arginine-rich foods [9
]. Dietary hempseed is also particularly rich in the omega-6 fatty acid linoleic acid (LA) and also contains elevated concentrations of the omega-3 fatty acid α-linolenic acid (ALA). The LA:ALA ratio normally exists in hempseed at between 2:1 and 3:1 levels. This proportion has been proposed to be ideal for a healthy diet [11
]. Other rich sources of LA [12
] are listed in Table .
Nutrient profile of hempseed*.
Rich sources of the essential fatty acid linoleic acid*.
The long chain PUFA that is found in the body ultimately originates from the diet and through elongation and desaturation of their dietary precursors, ALA and LA. Both families of fatty acids, n-3 and n-6, share and compete for the same enzymes (Δ6
-desaturase, and elongases) in their biosynthetic pathways. The Δ6
-desaturase enzyme is the rate-limiting step [9
]. Following its metabolism, LA can be converted into arachidonic acid whereas ALA will be converted into the long chain fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Figure ). A high LA intake interferes with the desaturation and elongation of ALA [14
]. Therefore, theorically, a lower ratio of omega-6/omega-3 fatty acids is more advantageous in reducing the risk of many of the chronic diseases of high prevalence in Western societies. The ratio of ω-6 to ω-3 fatty acids ranges from 20-30:1 in Western societies instead of the traditional (historic) range of 1-2:1 on which human beings evolved [15
]. This is thought to be closely associated with chronic diseases like coronary artery disease, hypertension, diabetes, arthritis, osteoporosis, inflammatory and autoimmune disorders and cancer.
Figure 1 Biochemical pathway for linolenic acid and α-linolenic acid transformation. ALA = α-linolenic acid; ARA = arachidonic acid; DGLA = dihomo γ-linolenic acid; DHA = docosahexaenoic acid; DPA = docosapentaenoic acid; EPA = eicosapentaenoic (more ...)
Hempseed is also a rich and unusual source of the polyunsaturated fatty acid gamma linolenic acid (GLA) (18:3n6) to the body. Additionally, another important biological metabolite of ALA and LA, stearidonic acid (18:4n3; SDA) is also present in hempseed oil (Figure ). Both can inhibit inflammatory responses [16
Recently, many studies have demonstrated that dietary interventions can play a central role in the primary and secondary prevention of several diseases. The PUFAs derived from fish, EPA and DHA, have been extensively studied. Based on the close relation between the pathways that metabolize ALA and LA, and the capacity of both to be converted into long chain fatty acids, plant sources of ALA (i.e. flaxseed, canola and others) have begun to attract more scientific attention for their potential to improve our health. However, because of legal regulations, lack of knowledge and some confusion about the differences between fiber hemp and marijuana, the growth of hempseed research has been slower than expected. In view of its long history of dietary usage, it is surprising that research on the effects of dietary hempseed in animal and humans has been limited. Furthermore, because of its expected nutritional value and the hypothetical benefits of LA and ALA against a variety of health disorders, a better understanding of the appropriate doses and presentation (oil, seed, etc) of hempseed should represent useful health-related information. It is important to point out that dietary hempseed as an energy containing food item introduces changes in the fatty acid composition of the diet and will inevitably replace other dietary components under an isocaloric condition. Previously some [18
] but not all authors [19
] have found differences in body weight after the administration of 30 ml/d of hempseed oil for four to eight weeks in humans. Finally, an identification of the target patient population (age, clinical condition, co-morbidities, etc) that may benefit the most from a supplementation of hempseed in the diet would also be important information.