The problem with mass marketers is that they often don’t keep up with science when it comes to the formulation of vitamin/mineral supplements.  This can pose a danger to you.   You need to know that certain nutrients, like iron, are not for everyone and should only be taken when tests show they are needed.

Iron Supplementation Not for Everyone.
It is now an established fact that free radicals generated by supplemental iron increase cancer and heart disease risk. Published studies show that elevation in markers of iron intake increase risk (by more than fivefold) of common degenerative diseases including heart attack and cancer. 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17

Despite this conclusive research very few commercial supplement companies have removed iron from their multivitamin formulas and public perception is often still that supplemental iron is beneficial.

Tiny Amounts of Antioxidants
Miniscule quantities of antioxidants in many multi vitamin/mineral formulas do little to protect against free radicals.  At the same time these formulas may include large amounts of iron (and sometimes copper) that are known free radical generators.

Excessive Amounts of Vitamin A
Many inexpensive poorly formulated multi/vitamin/mineral formulas containexcessive amounts of preformed vitamin A and inadequate amounts of vitamin D. One popular formula provided 25,000 IU of preformed vitamin A and only 400 IU of vitamin D.  The problem with this potency ratio is that in the presence of excess preformed vitamin A, the beneficial effects of vitamin D can be neutralized.18 Consumption of excess preformed vitamin A, as found in commercial multivitamins and modern cod liver oil, may cause bone toxicity in those with inadequate vitamin D status. One study showed that women with the highest intake of preformed vitamin A had 2.1 times more hip fractures.19, 20 A meta-analysis found that people who took preformed vitamin A supplements had a 16% increase in overall mortality,21 perhaps through antagonism of vitamin D.

This is not an issue with beta-carotene, as it converts to vitamin A in the body only on demand.

How Can You Identify a Safe Multivitamin Formula?
Do not take low-potency multivitamin formulas spiked with high amounts of iron and copper. Take a supplement with very little preformed vitamin A but lots of vitamin D.  Supplement with even higher amounts of vitamin D.

Added Protection
Take omega-3 fatty acids, antioxidants, Vitamin E with gamma tocopherol (which is critical to balance the effects of alpha tocopherol in the body) and vitamin K (which works with vitamin D to keep calcium in bones where it belongs).

References:
1. Salonen JT, Nyyssonen K, Korpela H, Tuomilehto J, Seppanen R, Salonen R. High stored iron levels are associated with excess risk of myocardial infarction in eastern Finnish men. Circulation. 1992 Sep;86(3):803-811.

2. Wells BJ, Mainous AG 3rd, King DE, Gill JM, Carek PJ, Geesey ME. The combined effect of transferrin saturation and low density lipoprotein on mortality. Fam Med. 2004 May;36(5):324-9.

3. Klipstein-Grobusch K, Grobbee DE, den Breeijen JH, Boeing H, Hofman A, Witteman JC. Dietary iron and risk of myocardial infarction in the Rotterdam Study. Am J Epidemiol. 1999 Mar 1;149(5):421-8

4. van der A DL, Peeters PH, Grobbee DE, Marx JJ, van der Schouw YT. Dietary haem iron and coronary heart disease in women. Eur Heart J. 2005 Feb;26(3):257-62.

5. Tuomainen TP, Punnonen K, Nyyssönen K, Salonen JT. Association between body iron stores and the risk of acute myocardial infarction in men. Circulation. 1998 Apr 21;97(15):1461-6.

6. Tzonou A, Lagiou P, Trichopoulou A, Tsoutsos V, Trichopoulos D. Dietary iron and coronary heart disease risk: a study from Greece. Am J Epidemiol. 1998 Jan 15;147(2):161-6.

7. Alissa EM, Ahmed WH, Al-Ama N, Ferns GA. Relationship between indices of iron status and coronary risk factors including diabetes and the metabolic syndrome in Saudi subjects without overt coronary disease. J Trace Elem Med Biol. 2007 21(4):242-54.

8. Pierre F, Tache S, Petit CR, Van der Meer R, Corpet DE. Meat and cancer: haemoglobin and haemin in a low-calcium diet promote colorectal carcinogenesis at the aberrant crypt stage in rats. Carcinogenesis. 2003 Oct;24(10):1683-90.

9. Stevens RG, Graubard BI, Micozzi MS, Neriishi K, Blumberg BS. Moderate elevation of body iron level and increased risk of cancer occurrence and death. Int J Cancer. 1994 Feb 1;56(3):364-9.

10. Mainous AG 3rd, Gill JM, Everett CJ. Transferrin saturation, dietary iron intake, and risk of cancer. Ann Fam Med. 2005 Mar-Apr;3(2):131-7.

11. Nelson RL. Iron and colorectal cancer risk: human studies. Nutr Rev. 2001 May;59(5):140-8.

12. Moyo VM, Makunike R, Gangaidzo IT, et al. African iron overload and hepatocellular carcinoma. Eur J Haematol. 1998 60:28–34.

13. Thompson KJ, Shoham S, Connor JR. Iron and neurodegenerative disorders. Brain Res Bull. 2001 55:155–64.

14. Sian-Hülsmann J, Mandel S, Youdim MB, Riederer P. The relevance of iron in the pathogenesis of Parkinson's disease. J Neurochem. 2011 Sep;118(6):939-57.

15. Jeong SY, Rathore KI, Schulz K, Ponka P, Arosio P, David S. Dysregulation of iron homeostasis in the CNS contributes to disease progression in a mouse model of amyotrophic lateral sclerosis. J Neurosci. 2009 Jan 21;29(3):610-9.

16. Weinberg ED. Iron loading: a risk factor for osteoporosis. BioMetals. 2006 19:633–5.

17. Richer S, Rudy D, Statkute L, Karofty K, Frankowski J. Serum iron, transferrin saturation, ferritin, and dietary data in age-related macular degeneration. Am J Ther. 2002 Jan-Feb;9(1):25-

18. Rohde CM, Manatt M, Clagett-Dame M, DeLuca HF. Vitamin A antagonizes the action of vitamin D in rats. J Nutr. 1999 Dec;129(12):2246-50.

19. Johansson S, Melhus H. Vitamin A antagonizes calcium response to vitamin D in man. J Bone Miner Res. 2001 Oct;16(10):1899-905.

20. Melhus H, Michaëlsson K, Kindmark A, et al. Excessive dietary intake of vitamin A is associated with reduced bone mineral density and increased risk for hip fracture. Ann Intern Med. 1998 Nov 15;129(10):770-8.

21. Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA. 2007 Feb 28;297(8):842-57.