Hemp Foods and THC Levels:
A Scientific Assessment
by Franjo Grotenhermen, M.D., Michael Karus, and Daike Lohmeyer
About the publisher
Table of Contents
3 Basis for Determination of THC Limits
3.2 Biological Basis
3.2.1 Acute perceptible and psychotropic effects
3.2.2 Non-perceptible and chronic physical effects
3.2.3 Factors reducing the biological efficacy of THC
3.2.4 Summary and conclusion on biological effects
4 THC Limits for Food
4.1 Consumption Habits
4.2 Existing THC Limits for Food
4.3 Derivation of THC Limits
Excursus I: THC and Alcohol in food
2.1 Extrapolation of different routes of administration to oral ingestion
2.2 Extrapolation of animal data to man
2.2.1 Interspecies comparison based on body weight
2.2.2 Interspecies comparison based on body surface
2.2.3 Interspecies comparison based on pharmacokinetics
2.2.4 Interspecies comparison based on precise toxicological data
2.3 Methodical basis for the determination of thresholds
3 Pharmacology and pharmacokinetics
3.1 Resorption and plasma level
Excursus II: THC in cosmetics and dermatics
3.2 Transport and metabolism
Excursus III: Detection of THC after ingestion of hemp-containing food
3.3 Influence of physical factors on THC content
3.4 Mode of action
3.5 Development of tolerance
3.6 THC effects and total toxicity
4 THC thresholds for psychotropic effects
5 Discussion of physical effects
5.1 Genetic material and cell metabolism
5.1.1 Cell studies
5.1.2 Studies with Cannabis users
5.2.1 Birth complications
5.2.2 Birth defects
5.2.3 Pregnancy outcome
5.2.4 Brain development
5.3 Hormonal system and reproduction
5.3.1 Sex hormones
5.3.3 Thyroid hormones
5.3.4 Glucose metabolism
5.4 Immune system
5.4.1 Cell-mediated immunity
5.4.2 Humoral immunity
5.4.3 AIDS infection
Since the early 1990s, countries around the world, particularly in Europe, have rediscovered hemp (Cannabis sativa) as a versatile, renewable raw material. The initial focus has been on fibers of high quality, for which a multitude of new technical applications have been developed, e.g. in the automotive industry. More recently, interest has also grown in the use of hemp seeds (botanical: achene-nut or little nut). Hemp seeds have been used for millennia for nutritional purposes but, in recent decades, knowledge of their nutritional value and taste has fallen into oblivion.
Currently, a large number of food items primarily made from hemp seeds are on the market in Europe, the U.S., Canada, and Australia. They include hemp oil, hemp breads and pastries, hemp pasta, hemp granola bars, hemp chocolate and hemp ice cream with hulled hemp seeds, hemp beer, cider blended with hemp flavored soda water, and hemp pastilles, to mention just a few. The following hempseed-based raw materials are used:
Two main factors support the use of hemp seeds and oil in food:
1. Hemp oil is particularly rich in polyunsaturated fatty acids, of which it contains approximately 90%. Of specific importance among them are the so-called essential fatty acids (EFAs), linoleic acid (50-70%) and alpha linolenic acid (15-25%). The latter particularly is found in only few vegetable oils. Due to its well-balanced fatty acid composition, hemp oil ranks with the edible oils of highest nutritive value. Fifteen to 20 grams of hemp oil are sufficient to supply a person's daily requirement of essential fatty acids. Integrated into the daily diet, hemp oil provides protection against several metabolic diseases and arteriosclerotic vascular diseases, which current studies attribute, at least partly, to excessive consumption of unsaturated and trans-fatty acids. Hemp oil, with its alpha-linolenic acid content, has effects comparable to fish oil and can therefore be used to prevent and treat cardiovascular diseases and chronic inflammations. Furthermore, hemp is one of the very few oliferous plants whose seeds contain gamma linolenic acid (GLA) (2-4%). A deficiency of gamma linolenic acid, which a healthy body produces from linoleic acid, can result in severe metabolic diseases. In these cases, intake of gamma linolenic acid may alleviate various diseases, including neurodermitis, premenstrual syndrome, rheumatoid arthritis, and diabetic neuropathy.
2. Hemp seeds and oils offer a new flavor which may be used in manifold forms by the food industry. Experts refer to the hemp seed, especially when hulled and roasted, as a "new nut flavor," for which large food enterprises show increasing interest.
This recent increase in the use of hemp seed products for nutrition, and the fact that small quantities of THC may enter into the food during processing, calls for the expeditious establishment of a legal framework, specifically a standard for the permissible residual content of THC. THC - delta-9-tetrahydrocannabinol - is the most relevant psychoactive ingredient of hemp. It is responsible for the intoxication produced by drug products, such as marijuana and hashish. It is also employed medically in the treatment of organically caused spasticity, pain, loss of appetite, and other symptoms. THC has been used for medicinal purposes in the U.S. since 1986 and is available in Germany since early 1998.
The meat of hemp seed itself does not contain any THC. It is primarily found in the flowers and involucres surrounding the seeds and, to a lesser extent, in the leaves. During seed processing, residuals of the flowers may enter hemp foods, particularly the oil. This applies in principle also to hemp varieties with a low THC content - so-called industrial hemp - the cultivation of which is permitted and subsidized in the European Union (EU). The amount of THC present in food products varies with plant variety, the effectiveness of seed cleaning and, possibly, the removal of hulls.
Generally, the THC content of hemp food is so low that pharmacological or even psychotropic effects can be excluded with certainty, even if large quantities of food are consumed. Toxicologically relevant concentrations of THC have been found in hemp oil only in a few isolated cases. The oil in question was of Swiss origin. It had been pressed from improperly cleaned seeds of high-THC varieties that are legal to grow in Switzerland. Due to these occurrences, the Swiss government introduced legal limits for THC in oil and other foods made from hemp seeds in 1996. As the manufacturers of hemp foods in Europe and North America became aware of the issue, they took measures to limit the THC content of their foods and complied with the Swiss limits. Consequently, in 1997 and 1998, no cases became known in which significant THC concentrations were found in hemp food.
So far, Switzerland is the only country worldwide where THC limits for food have been adopted. Canada passed a THC limit for hempen raw materials and semi-finished products this year. A limit for food is being prepared. Authorities in other European countries, the U.S., and Australia are urged to adopt binding THC limits. Two main reasons call for action:
- The consumer must be able to expect no-or only insignificant-quantities of THC when consuming food based on hemp seeds. Not only psychotropic effects should be excluded with certainty, but also undesired physical short-term and long-term effects.
- The specter of contamination by THC combined with the current unclear legal situation regarding THC limits obstructs the increased use of hemp in food. Only when this matter is settled will hemp seeds and hemp oil achieve the distribution they deserve based on their nutritional value and flavor.
As THC limits in hemp food are being considered by the authorities in Europe, North America and Australia, it has become apparent that a rational and scientifically founded basis for such limits is still lacking. This study was prepared by nova Institute in order to create such a basis. It is based exclusively upon pharmacological and nutritional research and applies commonly used safety margins. The study concludes with a list of recommended THC limits for various groups of hemp foods. All intermediate steps leading to these limits are presented understandably and made transparent.
The study consists of two parts. Part I summarizes the derivation of THC limits for food, as recommended by nova Institute. Part II presents a more detailed discussion of the pharmacological and toxicological evidence, as well as methodological issues related to the establishment of such values.
Our recommended limits suggest that it is possible to establish THC limits that guarantee the protection of the consumer while, at the same time, allow industry to employ hemp seeds for the production of nutritive and tasty hemp foods.
We hope that this study will provide comprehensive assistance to institutions around the world concerned with food, health, and consumer protection in the establishment of their own recommended limits for THC in hemp foods.
We would like to thank sincerely the various small- and medium-sized enterprises and institutions in Europe, the U.S., Canada, and Australia, who rendered this study possible through their kind support (for a list, see Chapter 5).
Finally we would like to thank Karen Brems, Marianne Kestler and Dr. Gero Leson for the translation of the study from German into English or, respectively, for their kind assistance in the translation and review of the text.
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This page last updated on 16 April 1999.