The 18 mg figure is correct as stated for its intended population. The NIH Office of Dietary Supplements lists the recommended amount as 8 mg for adult men 19 to 50 years and 18 mg for adult women 19 to 50 years, and notes that vegetarians who do not eat meat, poultry or seafood need almost twice as much because the body does not absorb nonheme iron in plant foods as well as heme iron in animal foods.

Harvard's Nutrition Source gives the same RDA values and attributes the higher requirement in women to menstrual blood loss.

Pomegranate is a poor iron source. USDA-derived data puts raw pomegranate at about 0.3 mg of iron per 100 g, roughly 4 percent of the daily value . At 0.3 mg per 100 g, 18 mg would require 6,000 g, which is exactly the 6 kg the post states. Other USDA-derived entries give slightly different values, for example 0.52 mg per 174 g cup for pomegranate arils , which works out to roughly 0.3 mg per 100 g as well, and one USDA seasonal produce listing rounds iron in a 100 g pomegranate to 0 mg . So the 6 kg arithmetic is sound on USDA numbers.

Liver iron is high but the 225 g figure appears slightly optimistic. USDA data for raw lamb liver gives 2.1 mg of iron per 28 g serving , which is about 7.5 mg per 100 g, and another listing of lamb liver shows about 7.04 mg of iron per 100 g . A separate composition entry for goat or sheep liver reports 6.6 mg of iron per 100 g . At 6.6 to 7.5 mg per 100 g, 225 g delivers roughly 15 to 17 mg, not 18 mg. To reach 18 mg of raw goat liver you would need roughly 240 to 275 g. Cooked liver, which loses water, is more iron dense per 100 g, so a cooked 225 g portion could reach or exceed 18 mg. The post does not state raw or cooked.

On absorption, the 5x figure is a simplification of a range, not a constant. Heme iron from animal foods absorbs at roughly 15 to 35 percent efficiency and is largely unaffected by other dietary factors, while non-heme iron from plants absorbs at only 2 to 20 percent and is strongly influenced by vitamin C, phytates, polyphenols and calcium eaten in the same meal.

The same ranges are reported in the literature overview, which notes overall iron absorption averages about 6 percent for men and 13 percent for women, that heme absorption ranges from 15 to 35 percent and is not significantly affected by diet, and that heme iron found in meat, poultry and fish has the highest bioavailability compared with the 2 to 20 percent absorption of non-heme iron.

A peer-reviewed review states that heme iron is absorbed with better efficiency than non-heme iron, that non-heme iron accounts for up to 90 percent of dietary iron and is affected by dietary factors and body iron status, and that heme iron is less affected by dietary factors. Depending on which point in each range you pick, the heme to non-heme ratio can be anywhere from roughly 2x to roughly 10x. Five is inside that span but is not a fixed or established multiplier.