Research Tips

May 5, 2009
If the label of a food or dietary supplement indicates 100% of the "Daily Value" for vitamin A, then one serving of the product contains about 200% of the daily intake currently recommended by the Institute of Medicine. Since high vitamin A intake may promote bone loss and birth defects, revision of labeling regulations is long overdue.
Nutr Rev. 2007 Oct;65(10):425-38.

May 11, 2009
Less than 2 milligrams of vitamin B-6 is all that is needed to meet an adult’s daily needs; only 200 milligrams consumed daily can cause nerve damage over time. Check that your dietary supplement does not contain toxic levels of this essential nutrient.
Ned Tijdschr Geneeskd. 2005 Nov 12;149(46):2545-6.

July 14, 2009
Adequate calcium is good for bone health, but it is possible to get too much. The Institute of Medicine considers 2500 mg/day to be the upper limit. Indiscriminate use of calcium- fortified foods plus supplements can easily go over that limit.
ODS Dietary Supplement Fact Sheet: Calcium

July 24, 2009
Vitamin B-6 is needed to make blood, keep the nervous and immune systems functioning properly, and regulate blood glucose levels. But, high doses of this vitamin can damage nerves - especially those in the arms, hands, legs and feet.
Institute of Medicine DRI Chapter on Vitamin B-6

August 6, 2009
It is important to consume adequate amounts of all essential nutrients. However, because excessive intake of some nutrients can be harmful, a “Tolerable Upper Intake Level” has been established for many nutrients. These values represent the maximum daily amount of a nutrient thought to not cause harm.
Establishing Upper Intake Levels for Nutrients

September 5, 2009
Vitamin B-6 is required in tiny amounts measured in thousandths of a gram. Many foods contain vitamin B-6, so it is unlikely to be too low unless your diet is extremely limited in variety or total food consumed. B-6 supplements in high doses, however, can cause nerve damage.
Ned Tijdschr Geneeskd. 2005 Nov 12;149(46):2545-6.

October 13, 2009
Fiber can help to prevent constipation. Excessively high fiber intake, however, can interfere with essential mineral absorption and can even cause constipation if inadequate fluids are consumed.
Nutr Rev. 2002 May;60(5 Pt 1):127-34.

December 22, 2009
High-fat meals may increase the risk of a heart attack for several hours because arteries narrow and blood flow slows. Enjoy the higher fat holiday foods, but in moderation.
Am J Cardiol. 1997 Feb 1;79(3):350-354

April 8, 2010
The theory that heart disease is caused by too much iron in the body has been refuted by a number of studies. Too much iron is mainly a concern for those with the genetic condition called hemochromatosis.
Can J Cardiovasc Nurs. 2009;19(1):26-32.

August 10, 2010
Foods and food components that show potential for preventing cancer are not necessarily beneficial during the treatment of cancer. A review of clinical trials reported that supplementation with vitamins C and E and beta carotene should not be used during chemotherapy.
J Natl Cancer Inst. 2008 Jun 4;100(11):773-83.

August 24, 2010
Too much of a good thing can be bad. This applies to nutrients and even exercise. “Tolerable Upper Intake Levels” have been established for many nutrients to help people know how much is too much.
Proc Nutr Soc. 2003 May;62(2):413-20.