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Frequently Asked Questions

Frequently Asked Questions - Nutrition 3 - Other Vitamins and Minerals

What about vitamin A?

Preformed vitamin A is not needed by the body, it can be synthesized by ingestion of carotene (often called provitamin A). Excess consumption of pre-formed Vitamin A can be dangerous. Good Carotene sources include: Green leafy vegetables, yellow fruits and vegetables.

What about vitamin D?

Preformed vitamin D is not needed by the body, it can be synthesized by exposure to sunshine of dehydrocholesterol present in the skin. Vitamin D created this way lasts in the body for many months such that it is possible to "top-up" one's vitamin D levels over the summer for the coming winter. Excess consumption of pre-formed Vitamin D can be dangerous. The Vitamin D in cow's milk is artificially added. In the UK margarine is fortified with vitamin D by law and some soya milks are also fortified.

What about calcium?

Green leafy vegetables such as kale are as good or better than milk as calcium sources. Other good sources include: White/Wholemeal bread, Taco Shells, Oats, Soyabeans, Tofu, Almonds, Brazil Nuts, Pistachios, Sunflower Seeds, Sesame Seeds, Flax Seed, Carob, Carrots, Cabbage, Garlic, Parsley Spirulina, Chives, Seaweed, Cauliflower, Okra, Cassava, Figs, Papaya, Rhubarb, Molasses...

The National Research Council itself (which set the RDA values in the first place), acknowledges that people have been able to maintain calcium balance on intakes as little as 200 - 400 gm/day. They recommended the 800 mg/day because of the excessively HIGH PROTEIN diet of most Americans (see NRC, Recommended Dietary Allowances, 9th Ed., 1980, p. 120-29)

Further information on Calcium:




Further information on Nutriton in general:


FAQ index

Should I worry about iron on a vegetarian/vegan diet?

To quote Vegetarian Times (August 1992, p. 60):

"Iron deficiency, unlike protein deficiency, sometimes is a real problem, but meat is not the answer. The American Dietetic Association said in 1988 that vegetarians don't have a higher incidence of iron deficiency than nonvegetarians.

If you are concerned about getting enough iron, avoid eating iron-rich foods along with substances that inhibit iron absorption: phyates (found in high-bran and unmilled cereals), polyphenols (such as tannins in tea) and calcium. Eat iron-rich foods along with foods containing vitamin C, which aids absorption. Good sources of iron include dried figs and prunes, dark-green leafy greens, legumes, certain whole grains such as quinoa and millet, blackstrap molasses, nuts and nutritional yeast. Acidic foods cooked in cast-iron pans are also good sources of the mineral."

How long should I wait between drinking tea and eating iron enriched foods?

from a member of ivu-sci:
I recall a lecture some years ago in which the speaker (a nutrition expert from Oxford Brookes University) recommended that vegetarians avoid drinking tea within one hour either side of a meal.
How strict one should be about this clearly depends on other factors such as the strength of the tea and total non-haem iron intake. (Non-haem iron is the sort available to veg*ns, the other sort is haem iron which is found only in meat and fish.)

Vitamin C enhances non-haem iron absorption, whilst phytate and polyphenols (including tannin found in tea and other beverages such as coffee and red wine) are major inhibitors of non-haem iron absorption. Thus, the iron absorbed from a meal containing non-haem iron may be doubled if the meal is taken with a glass of orange juice or reduced to one-third if taken with tea.

Reference:
Chapter 9 (Iron) of Essentials of Human Nutrition
Jim Mann & A Stewart Truswell (eds)
Oxford University Press, 1998.

Are there any supplements I could take to increase the amount of iron in my body?

from the UK:
 I find that Superdrugs own brand of Multivitamins plus Iron is really good. As well as providing 100% RDA of iron, it also provides Vitamins A, D, E, C, B1, B2, B6, B12, Niacin, Folic Acid, Biotin and Pantothenic Acid. It's only around £3.00 for 120 1-a-day tablets.

Which vegetables are rich in iron?

from members of ivu-sci::
Dried fruits, wholegrains (including wholemeal bread), nuts, green leafy vegetables, seeds and pulses (chickpeas, baked beans, lentils etc.)are rich sources of iron.
These foods are generally consumed in reasonable quantities so can provide a good proportion of daily iron requirements. Also of relevance are parsley, watercress, edible seaweeds and black molasses, although none of these are usually consumed in large quantities.
Iron is absorbed less well from plant based foods than from meat, as it is in the non-haem form, but it's absorption is improved by the presence of Vitamin C, malic acid and citric acid. Good Vitamin C sources are green leafy vegetables (including cauliflower), citrus fruits, mangoes, tomatoes and potatoes. Citrus fruit is also a source of citric acid, whilst malic acid is found in apples, plums and pumpkins (amongst other foods). Phytates (such as in nuts, grains and seeds) can reduce iron absorption, as can tannins (from tea). Generally, because of the high dietary intake of iron rich foods in a balanced vegan diet, these two negative factors are not usually a problem but iron deficiency can occur as a result of heavy menstruation.

Vegan Nutrition (Gill Langley, The Vegan Society, 1995) lists "dried fruits, whole grains (including wholemeal bread), nuts, green leafy vegetables, seeds and pulses" as rich plant food sources of iron. The absorption of iron is enhanced by the presence in the same meal of vitamin C (plentiful in fruits and vegetables), but can be reduced by tannins (from tea) and phytates (from nuts, grains and seeds). The use of iron cookware can also increase iron intake.

Further information on Iron: