Almond

Scientific Name(s): Prunus dulcis (P. Mill) D.A. Webb, Family: Rosaceae. Synonyms: Amygdalus communis L., Amygdalus dulcis P. Mill, Prunus amygdalus Batsch, Prunus communis (L.) Arcang., Prunus dulcis (Mill.) D.A. Webb var. amara (DC.) Buchheim

Common Name(s): Almond milk , almond oil ; amygdale amara , amygdalin , bitermandel , bitter almond , ku wei bian tao , laetrile , oil of almonds , sweet almond , vitamin B17 , volatile almond oil

Clinical Overview

Uses of Almond

Almonds are used as a dietary source of protein, unsaturated fats, minerals, micronutrients, phytochemicals, alpha-tocopheral, and fiber, as well as in confectioneries. It also has been examined for its lipid-altering effects. The almond derivative laetrile/amygdalin has been used as an alternative cancer treatment, but there is a lack of clinical evidence to support this use. Laetrile is banned by the U.S. Food and Drug Administration (FDA) and in Europe for use in cancer therapy.

Almond Dosing

Trials of almond dietary supplementation or laetrile in adults have used 50 to 75 g/day of sweet almonds.

Contraindications

Allergy to almonds or its products.

Pregnancy/Lactation

Consumption of bitter almond or laetrile is not recommended in pregnant or breast-feeding women because of insufficient data and a theoretical risk of birth defects. Consumption of sweet almond generally is recognized as safe when used as food. Avoid dosages above those found in food because the safety is unproven.

Almond Interactions

None well documented.

Almond Adverse Reactions

Allergies. Adverse reactions similar to those of cyanide poisoning have been reported.

Toxicology

Cyanide poisoning and death have resulted from laetrile and bitter almond consumption.

Botany

The almond, apricot, cherry, peach, and plum are members of the Rosaceae (rose) family. The almond is distinct because its seed is edible, while the outer pulp is hard, inedible, and juiceless. The genus Prunus (plum), to which the almond tree belongs, is synonymous with Amygdalus in the U.S. Department of Agriculture's PLANTS Database , but the literature remains confusing and often categorizes the sweet and bitter almond in different genera. 1

The plant, a moderate-sized tree, was probably introduced to the United States from eastern Europe or western Asia. The United States, especially California, is the world's major producer of almonds. 2 Many varieties of the plant differ in the flower color and form, and in the size of the fruit or shell. Varieties with entirely pink flowers produce sweet almonds; those with flowers that are almost white at the tip of the petals and are red/pink at the base produce bitter almonds. When fully ripe, the green outer covering of the fruit dries and splits, and the almond shell (endocarp) drops out. The almond seed is rounded at one end and pointed at the other, with a yellow, fibrous outer covering. 1

History

References to the almond are found in Greek mythology, the Bible, and in Shakespeare's writings. In the Middle Ages, almonds already were commercially important. 3

Amygdalin was isolated by French chemists in 1830, and reports of its use as an anticancer agent date back to 1845 in Russia. In the United States, records show laetrile was used as a cancer treatment in the 1920s and was patented in the 1950s as a supposedly nontoxic form of amygdalin. 4

The FDA has banned the sale of laetrile as a medicinal product; however, it remains available and is promoted in Mexico where it often is produced. 4 Sweet almond is historically described as Mistura Amygdalae, Pulvis Amygdalae Compositus, and Almond Oil in the British Herbal Pharmacopoeia .

Chemistry

The fundamental difference between bitter and sweet almond is the presence of amygdalin. Sweet almond does not contain amygdalin and can be eaten safely. 5 Amygdalin also exists in the seeds of apricots, cherries, and plums. 6

Amygdalin is hydrolyzed to yield glucose, benzaldehyde, and hydrocyanic acid. The production of cyanide defines cyanogenic glycosides. Enzymatic release of cyanide can occur in the presence of beta-glucuronidase, an enzyme found in the seeds and in the human intestine. 6 When the cyanide component is removed, the resulting oil is referred to as bitter almond oil and consists mostly of benzaldehyde. This oil is toxic when consumed in large amounts.

The term laetrile often is used interchangeably with amygdalin, but they are not the same chemical entity. Laetrile is a neologism, conflating the terms laevorotatory and mandelonitrile, and is used to describe a semisynthetic derivative of amygdalin. 7 Most laetrile from Mexico is made from crushed apricot seeds and is a mixture of amygdalin and neoamygdalin, which are mandelonitrile gentiobiosides. Other laetrile products of varying composition are commercially available. 7 , 8 , 9

Other chemical compounds in the almond include 3 major components: betulinic acids, oleanic, and ursolic, which have shown anti-HIV, anti-inflammatory, and in vitro antiproliferative activities. 10 , 11 , 12 , 13 Other acids (corosolic and maslinic) have been identified as aldehydes. 10 Antioxidant flavonoids quercetin, isorhamnetin, quercitrin, kaempferol, and morin have been isolated. 11 , 12 , 14 Prunasin, another cyanogenic compound, is found only in the vegetative parts of the almond plant. 15

Almond Uses and Pharmacology

Despite promising in vitro experiments, the use of amygdalin as a cancer treatment has not been validated by any clinical trials.

The National Cancer Institute sponsored phase 1 and phase 2 clinical trials in the 1980s but found no evidence to support the use of laetrile in the treatment of cancer. 4 Interest in the effectiveness of laetrile/amygdalin in treating cancer continues. A Cochrane protocol for a meta-analysis of all relevant clinical trials exists, but the results are pending. 7

Laetrile is banned by the FDA and in Europe for use in cancer therapy. 7 , 16

Almond nuts are a source of protein, unsaturated fats, minerals, micronutrients, phytochemicals, alpha-tocopherol, and dietary fiber. 2 , 17 , 18 , 19 , 20

Almond supplementation has been investigated by several researchers, all finding favorable lipid-altering effects. Diets rich in almonds show increased high-density lipoprotein (HDL) and reduced low-density lipoprotein (LDL), total cholesterol:HDL ratio, and LDL oxidation. Therefore, risk for coronary heart disease is reduced. 18 , 19 , 21 Additionally, no increases in body weight were observed after 6 months of almond supplementation, 20 but insulin sensitivity was not improved in patients with type 2 diabetes. 17

Almonds are considered a good source of tocopherol to meet the recommended daily allowance for vitamin E, now increased to 15 mg/day. 22

The protein component is primarily composed of amadin, which confers the antigenicity of the nut in IgE-mediated allergy. 2

Almond-based diets are possibly deficient in selenium, riboflavin, and pantothenic and folic acids. 23 Published case reports have shown that infants fed almond milk exhibited hypoalbuminemia and consequent peripheral edema as well as deficiencies in calcium and iron. 24

Almond oil has been used with phenol to treat rectal prolapse in infants 25 and as a carrier of other essential oils in massage therapy.

Dosage

There is no widely accepted standard for laetrile/amygdalin dosing because of the potential for toxicity. 4

Trials of almond dietary supplementation in adults have used 50 to 75 g/day of sweet almonds. 19 , 20 , 21

Pregnancy/Lactation

Consumption of bitter almond or laetrile is not recommended in pregnant or breast-feeding women because of insufficient data and a theoretical risk of birth defects.

Cyanide has not been reported as a direct cause of birth defects in humans. Birth defects, harmful effects on the reproductive system, and skeletal abnormalities have been reported in mice fed on water containing sodium cyanide and in hamsters given oral laetrile. 5 , 26

Children born to mothers exposed to cyanide and thiocyanate during pregnancy have exhibited thyroid disease. 26

Interactions

Almond consumption may possibly enhance the drowsiness caused by benzodiazepines, barbiturates, and narcotics. 5

Coadministration of high-dose vitamin C and almonds may result in symptoms of cyanide toxicity. 4

Toxic reactions were observed in mice fed almond oil and alcohol. 5

Adverse Reactions

Allergies to nuts are common in the United States, affecting an estimated 0.5% of the population. 2 , 27 Adverse reactions similar to those of cyanide poisoning have been reported. 4

Toxicology

Cyanide poisoning and death have resulted from laetrile and bitter almond consumption. 5 , 6 A minimum lethal dose of cyanide is estimated at 50 mg (or 0.5 mg/kg body weight). 6 Oral amygdalin/laetrile is considered 40 times more toxic than the intravenous form because of its conversion to hydrogen cyanide by enzymes in the intestine. 4 , 6 However, sweet almond seeds do not contain amygdalin and can be eaten safely. 5

Symptoms of cyanide poisoning (eg, coma, cyanosis, dizziness, headache, hypotension, nausea, neuropathies, ptosis, vomiting) may be potentiated by eating foods containing beta-glucosidase (eg, bean sprouts, carrots, celery, peaches) or by taking high doses of vitamin C. 4

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