Rapeseed and canola oil

[Guest guest]

Hi and everyone,

I never knew what rapeseed was till I moved to Germany where the fields bloom

in early summer with beautiful yellow carpets of rapeseed. Maybe this partially

explains the high incidents of thyroid problems in my area.

MA

------------------------------------------------------------------------ZZXX

[Guest guest]

Hi Everyone,

When doing some searches for copper deficiency studies I have repeatedly run

across animal studies on rapeseed meal. Rapeseed (Brassua napus) is used as

animal feed and people have found that the animals don't grow well on it.

Because it is a cheap source of protein and fat research efforts have been

spent trying to overcome this problem.

Studies show that animals fed rapeseed meal experience goiters and sometimes

have thyroid weight increased 3-4 times and it is considered a goitrogen.

Also animals experience serious liver and heart damage from rapeseed. The

damaging ingredient in rapeseed is though to be erucic acid.

Other studies have shown that iodine supplementation helps but does not

reverse the problem, while iodine plus copper nearly correct the problem.

Another study showed that the negative effects can be reversed by zinc

supplementation. Apparently rapeseed can cause iodine, copper, and zinc

deficiencies.

Rapeseed is used as a human food source also, and the oil is known as canola

oil. Because of the low cost rapeseed meal and oil is used in many food

products. Because of its proven ability to cause iodine, copper, and zinc

deficiencies, I think it's best to avoid canola oil and look for rapeseed as

an ingredient in foods. Many animals such as cows, chickens, and pigs are fed

rapeseed. Whether eating the meat, eggs, or milk of these animals will cause

effects is unknown.

Here are three studies if you're interested:

Title

Effect of varying glucosinolate and iodine intake via rapeseed meal diets on

serum thyroid hormone level and total iodine in the thyroid in growing pigs.

Author

Sch¨one F; Jahreis G; Lange R; Seffner W; Groppel B; Hennig A; L¨udke H

Address

Karl-Marx-University Leipzig, School of Animal Production and Veterinary

Medicine, Department of Animal Nutrition-Chemistry, Jena, Germany.

Source

Endocrinol Exp, 24(4):415-27 1990 Dec

Abstract

In a trial with 50 fattening pigs (20 kg initial body weight), the effect of

untreated rapeseed meal (RSM) (148 mmol glucosinolates and aglucones per kg

dry matter) on the thyroid was compared with RSM treated with Cu2+ (9.5 mmol

glucosinolates and aglucones per kg dry matter) and soybean meal (SBM). The

diets containing 8% RSM were supplemented with 0.0625-1.0 and the SBM diet

(control) with 0.125 mg iodine kg-1 (I). In comparison with SBM fed control,

RSM treatment with Cu2+ resulted in a complete normalization of feed intake

and growth. Only untreated RSM without I supplementation depressed performance

and resulted in symptoms of I deficiency, but the thyroid and liver weight

were also increased and the serum T4 content was significantly reduced in

animals which were given RSM not supplemented with I, but treated with Cu2+.

In young pigs (4 weeks) a plateau of the serum T4 content was achieved from

0.5 mg I kg-1 of the RSM diet onwards. In contrast, when the concentration of

goitrogens was reduced by the treatment with Cu2+, the serum T4 level was

increased significantly in groups fed with 0.125 mg I kg-1 diet and more. In

older pigs (15 weeks) neither the content of goitrogens nor the I dosage

affected the serum T4 level. On the other hand, the I content in the thyroid

was a good indicator of the different goitrogenicity of the diet in the case

of a low I supply. The present investigations show that pig diets with RSM

(greater than 10 mmol glucosinolates and aglucones kg-1) should contain at

least 0.5 mg I kg-1, but 0.1 mg supplementary I per kg is sufficient in diets

without or with a low content (less than 1 mmol glucosinolates and aglucones

per kg-1) of antithyroid compounds.

Title

Rapeseed induced liver haemorrhage, reticulolysis and biochemical changes in

laying hens: the effects of feeding high and low glucosinolate meals.

Author

Martland MF; EJ; Fenwick GR

Source

Res Vet Sci, 36(3):298-309 1984 May

Abstract

Rapeseed meal hepatosis was produced by feeding high and low glucosinolate

meals as a source of protein (about 200 g kg-1 diet) but could not be

distinguished histologically from fatty liver-haemorrhagic syndrome which

occurred in birds on the control diet. Both types of meal increased

haemorrhage, reticulolysis and lymphoproliferation in the liver, reduced the

packed cell volume and caused thyroid enlargement. Haemorrhages emanated from

ruptured intrahepatic portal veins, capillaries and sinusoids and were

associated with degenerative changes in vessel walls. Haemorrhage and

reticulin scores were correlated. Parenchymal necrosis occurred only around

large haematomas and caused increased aspartate transaminase activity in the

plasma. Both meals also caused hyperglycaemia and reduced the plasma

triglyceride content. Only the high glucosinolate meal decreased egg

production, caused liver enlargement and reduced the plasma urate level. The

addition of myrosinase enhanced its effects on egg production and packed cell

volume but did not increase its hepatotoxicity.

Title

Heart pathology in rats fed partially hydrogenated fish oil, rapeseed oil or

peanut oil for 30 weeks.

Author

Svaar H; Langmark FT

Source

Acta Pathol Microbiol Scand [A], 88(3):179-87 1980 May

Abstract

132 male Sprague-Dawley rats were given diets for 30 weeks including rapeseed

oil with 41.4% erucic acid, partially hydrogenated fish oil with 15.1%

docosenoic acids, or peanut oil with no docosenoic acids. Four diets were

isocaloric and contained respectively 21% rapeseed oil (8.7% w/w erucic acid),

10.5% rapeseed oil and 10.5% peanut oil (4.4% w/w erucic acid), 21% partially

hydrogenated fish oil (3.2% w/w docosenoic acids) and 21% peanut oil. The

fifth diet contained 4.3% peanut oil. The relative heart weights increased in

rats fed rapeseed oil and partially hydrogenated fish oil, and abnormally

enlarged hearts were found in 32% of the rats fed 21% rapeseed oil and in 5%

of those fed 10.5% rapeseed oil. Heart lesions consisting of focal or

confluent destruction of muscle cells were seen in all groups. The incidence

was 96% and the average severity grade 2.5 when 21% rapeseed oil was given,

and 61% and 1.3 respectively when 10.5% rapeseed oil was given. Minor heart

lesions were found in 14% of the rats fed 21% partially hydrogenated fish oil,

in 39% of those fed 21% peanut oil and in 12% when 4.3% peanut oil was given.

It is concluded that partially hydrogenated fish oil is markedly less

cardiopathogenic than high erucic rapeseed oil. The heart lesions that were

found do not differ in incidence, severity or morphology from those found when

peanut oil was given, or from those reported when other control fats and oils

are given to rats for prolonged feeding periods.

------------------------------------------------------------------------