Food Attack ! Liver

The liver of mammals, fowl, and fish are commonly eaten as food by humans.

Animal livers are rich in iron and Vitamin A.  However, very high doses of vitamin A have the potential to be toxic and can cause hypervitaminosis A, a dangerous disorder.  In 1913, Antarctic explores Douglas Mawson and Xavier Mertz were both poisoned, the latter fatally, from eating husky liver.  Inuit will not eat the liver of polar bears or seals as they contain so much vitamin A as to be poisonous to humans.

Poisoning is less likely from consuming oil-based vitamin A products and liver than from consuming water-based and solid preparations.

As vitamin A is fat-soluble, disposing of any excesses taken in through diet is much harder than with water-soluble vitamin B and C.  Vitamin A toxicity may lead to nausea, jaundice, irritability, anorexia , vomiting, blurry vision, headaches, hairloss, muscle and abdominal pain and weakness, drowsiness, and altered mental status.

In general, acute toxicity occurs at doses of 25,000IU/kg of body weight, with chronic toxicity at 4,000IU/kg of body weight daily for  6 – 15 months.  In people with renal failure, 4000 IU/kg can cause substantial damage.  Children can reach toxic levels at 1,500 IU/kg of body weight.

In addition, excessive alcohol intake can increase toxicity.

Unrelated to its vitamin content, the liver of the pufferfish,, which  is consumed in Japanese cuisine as fugu, , contains the highest concentration of neurotoxin which characterizes the species.  As a result, it is generally not eaten, and indeed consumption is forbidden by Japanese law.

Vitamin A content of various animal liver :

Liver of,	IU / 100g
foie gras	3,333
chicken	13,328
pig	17,997
lamb	24,945
cow	31,714

note : An IU ( International Unit ) equals to 0.3 μg of retinol or 0.6 μg of β-carotene

Recommended Dietary Allowance by USDA :

Life Stage Group	RDA	Upper Limit
	μg/day	μg/day
Infants
0–6 months	400	600
7–12 months	500	600
Children
1–3 years	300	600
4–8 years	400	900
Males
9–13 years	600	1700
14–18 years	900	2800
19 - >70 years	900	3000
Females
9–13 years	600	1700
14–18 years	700	2800
19 - >70 years	700	3000
Pregnancy
<19 years	750	2800
19 - >50 years	770	3000
Lactation
<19 years	1200	2800
19 - >50 years	1300	3000

Source :

Wikipedia

USDA Nutrient Data Laboratory

USDA National Agricultural Library