How do you know that any given vitamin supplement (I'm thinking multivitamins, but it can really apply to any) is actually having a beneficial effect? In other words, how can you know if you are getting your money's worth? And how do you know if you really need vitamin supplementation, especially if you already eat a variety of clean, healthy foods?

First, let's tackle why you should take them:

Excessive-processing and refining of foods (i.e. refining wheat flour removes folic acid).

Modern Agricultural Practices (depletion of nutrients in the soil due to intensive farming, poor crop rotation periods, Genetic modification, chemical re-fertilization i.e. only NPK which basically reduces the nutritional quality to humans - as well as leaving potentially harmful toxic residues). The use of pesticides is shocking with well documented evidence of popular foods being contaminated.

Storage Methods: Much of the 'fresh' fruit and veg in our supermarkets have been in cold storage for six to nine months, during which time the nutrient content can fall dramatically. Studies show that the nutrient value of these foods can fall dramatically. In a recent study held in Florida, a randomly selected orange contained 70mg of vitamin C, another just a trace.

Cooking Methods: It is a fact that heating foods will destroy or reduce a large proportion of the nutrient content in a food (especially antioxidants).

A study looking at nutritional values of foods over a 50 year period dating back to 1940 was performed recently (Thomas D. Mineral depletion in foods over the period 1940 to 1991. The Nutrition Practitioner. 2001;2.1:27-29. ). Using data from the McCance and Widdowson British Food Journals (the standard reference): "The Chemical Composition of Foods" published periodically by the Medical Research Council. The researcher showed that, compared to 50 years ago, on average:

27 varieties of vegetables contain 46% less calcium

17 varieties of fruit contain 16% less calcium

10 cuts of meat contain 41% less calcium

Milk contains 4% less calcium

Cheddar cheese contains 11% less calcium

These are just a few examples. There are equally worrying figures for other important minerals such as potassium, phosphorous, magnesium and iron (Thomas D. Mineral depletion in foods over the period 1940 to 1991. The Nutrition Practitioner. 2001;2.1:27-29. )

Other things we can't escape:

Stress
Radiation from the sun
Air pollution
Toxic chemicals in water

The respected Journal of the American Medical Association recently reversed its original position on vitamins and now actively recommends taking a daily multi-vitamin.

There is so much research supporting taking a multi-vitamin, where do we begin? Here are just a few recent studies:

Antioxidants Appear to Protect Against Type 2 Diabetes
Montonen J, Knekt P, Jarvinen R, Reunanen A. Dietary anti oxidant intake and risk of type 2 diabetes. Diabetes Care. 2004 Feb;27(2):362-6.

They affect the elderly:

Antioxidants and Physical Performance in the Elderly
Cesari M, Pahor M, Bartali B et al. Antioxidants and physical performance in elderly persons: the Invecchiare in Chianti (InCHIANTI) study. Am J Clin Nutr 2004;79:289-94.

The young:

Asthma Prevalence in Youth Linked to Serum Antioxidant Levels
Rubin RN, Navon L, Cassano PA Relationship of serum antioxidants to asthma prevalence in youth. Am J Respir Crit Care Med. 2004 Feb 1;169(3):393-8.

Women:

Folate Intake may be Linked to Ovarian Cancer
Larsson SC, Giovannucci E, Wolk A Dietary folate intake and incidence of ovarian cancer: the Swedish Mammography Cohort. J Natl Cancer Inst. 2004 Mar 3;96(5):396-402.

Men:

Folate Intake Related to Stroke Risk in Men
He K, Merchant A, Rimm EB, Rosner BA, Stampfer MJ, Willett WC, Ascherio A Folate, vitamin B6, and B12 intakes in relation to risk of stroke among men. Stroke. 2004 Jan;35(1):169-74. Epub 2003 Dec 11

In this study, it was determined that the second largest cause of death in the U.S. in 2000 was poor diet and physicial inactivity (400,000 deaths):

Mokdad AH, Marks JS, Stroup DF, Gerberding JL Actual causes of death in the United States, 2000. JAMA. 2004 Mar 10;291(10):1238-45.

The USDA surveyed 21,500 Americans in 1982 to find that not a SINGLE ONE obtained 100% of the USRDA of ten key nutrients ... and the USRDA is not even the amount for optimal health, it is the minimum to avoid certain specific diseases! In some cases, much more than the USRDA may be needed for optimal health.

(USDA National Food Consumption Survey, Guthrie and Crocetti, 1982)


So, I think that establishes the need for a multi-vitamin. I know many doctors who have successfully managed chronic illnesses ranging from fibromyalgia, multiple sclerosis, to arthritis and other causes with simple, nutritional supplementation. If they can reduce or eliminate symtpoms from these debilitating diseases with multi-vitamin supplementation, imagine what we DON'T know about how they may play a role in preventing the onset of certain conditions!

As for quality, you have good cause to be concerned.

The majority of multi-vitamins are woefully inadequate. In a recent study at Yale New Haven Hospital, many were made with the wrong ratios of nutrients altogether. Of the 257 vitamin products tested, only 49 were judged to be adequate.

In his Comparative Guide to Nutritional Supplements, Lyle MacWilliams surveyed I believe it was 8 different doctors renowned for their nutrition knowledge and came up with a "blended standard" or average recommendation for daily supplemental intake. He then investigated 1,000 supplements - only 500 made it into his book, and if I remember correctly, only 5 scored in the 90th percentile or higher (meaning only nine came within 90% of reaching the optimal amounts recommended by the panel of nutritionists and doctors).

Here are some guidelines to find a quality multi-vitamin:

1. Third-party quality controls. The US FDA does have a standard for quality assurance. The problem is that supplement manufacturers don't have to adhere to them! However, those that do, MUST follow the standard in order to make claims. Therefore, look for products that follow PHARMACEUTICAL GRADE General Manufacturing Practices (GMP) - some follow GMP but use food grade, which is much lower quality.

http://www.fda.gov/cder/gmp/

2. Third-party dissolution standards. The vitamin may contain materials, but are they processed adequately for your body to digest them? The U.S. Pharmacopeia issues standards, and the bottle should disclose whether or not this USP standard is followed:

http://www.usp.org/

3. Third-party quality testers. While it does cost money, consider subscribing to a service like:

http://www.consumerlabs.com/

They regularly test products and members are allowed to review the results. Look for companies that consistently have in the bottle what is claimed on the label.

4. Potency guarantee - the manufacturer should back their product with a money-back, potency guarantee.

Those are a few items. I do sell supplements myself - my passion is to educate and empower others to make the same healthy choices I have made in my life. For that reason, I wanted to make sure to provide you with objective, referenced information and not include anything specific to my company.

I hope this helps!

Jeremy

Wow, Jeremy! Did anyone ever tell you you talk to much? ;) :D

You've definitely presented a strong argument with an abundance of evidence for taking a multi. I do have some followup questions, however.

1. How can I know if, even given how I eat, I am lacking in one or more vitamins? Does it even matter to make such a determination? I'm not looking to make up for this or that. I am, however, concerned that perhaps I do get enough of some vitamins and that a HQ multi will not lead to overdosing. Isn't it true that too much of some vitamins can lead to deficiencies in others?

2. Is there any benefit to liquid vs. solid multis? I used to take a liquid multi several years ago that mixed well in orange juice.

3. I looked for the McWilliams book couldn't find it. What do you suggest for finding a good multi? I know you're biased, but would it be just as good to get one from USANA? I don't really want to spend hours researching which multi is best for me.

Thanks again for taking so much time to provide such useful information!

Justin

Justin, I do talk too much. I have been told that many times! However, I try to give too much information rather than too little, so people can benefit from going off to do their own research.

My answers to your questions:

1. I am not aware of any tests that will tell you exactly what you are lacking. The majority of studies indicate that even elite athletes with great nutrition plans still benefit from taking additional vitamins. It is not entirely correct that too much of one vitamin creates deficiencies, but vitamins do compete for "receptors".

For example, if Vit 1 and Vit 2 have the same receptor and you intake the improper ratio, then Vit 1 will prevent Vit 2 from being absorbed. Nature seems to have a knack for always combining vitamins in the appropriate amounts - i.e. if a whole food is rich with Vit 1 then it has extra Vit 2 to compensate for the reduced absorption, etc. Having said that, well-manufactured multis take this into account. They don't just base the dose on "100% of the USRDA" but rather on the appropriate intereactions. Since you are only taking it once or twice per day, you also benefit from meals in between where you are getting additional nutrients from the natural sources, so competition isn't as much of an issue.

As for overdosing, this, too, is accounted for with a quality multi. Just as an example, several of the top multis contain no iron. Supplemental iron in large doses is toxic. On the other hand, Vitamin A has many health benefits. Too much Vitamin A can be toxic. Beta carotene, however, has not been shown to be toxic in large amounts, and the body naturally converts this to Vitamin A. Anything it doesn't need gets converted to other anti-oxidants or passes through your system unharmed. Therefore, a good multi may contain Vitamin A as beta carotene rather than straight Vitamin A, to make sure there are not issues for potential toxicity.

Good multis will have higher doses of the non-toxic substances and carefully selected doses of the ones that could potentially be toxic.

Fortunately, most vitamins and minerals have been studied in great detail. The majority of the issues with overdose and toxicity comes not from the combination of the supplement + natural food, but from taking too many supplements. For example, taking an iron supplement plus a multi with iron, or taking a multi with Vitamin E, taking straight vitamin E, then consuming a product with sythetically added Vitamin E. So if you cover your baseline with a good multi, then get straight protein powders instead of the ones that have vitamin sprays in them to look more impressive by listing 100% of this or 50% of that on the label, then you shouldn't encounter problems.

2. Liquid vitamins actually may be less beneficial. Many vitamins are not stable in water. Water contains molecules that are polarized, meaning they have a slightly charge on either end. This tends to allow them to react to certain substances (which is why so much dissolves in water). Many vitamins are water-soluble and actually break down in water. Most liquid multis that I have investigated use hype to convince the reader that their super-duper propietary method assures maximum absorption (based on their own, hidden, in-house studies). There are a few products that may absorb better in liquid form, such as Vitamin E. That is why you often find this as a liquid in gel caps, but the majority of vitamins and minerals are best taken in pill form. The USP has more information on this.

3. You can find the guide at Amazon.com. There is also this site: http://www.comparativeguide.com/ that contains the information.

I wish I had the guide with me to tell you the top five. Usana, Pharmanex, and Rexall Sundown are three of the top rated ones, if I remember correctly.

As for taking the Usana, that is my obvious choice, I endorse it without batting an eye because I have so many clients who have giving me nothing but positive testimonials - it's what I take, my wife takes, my children take, my mother takes, my grandmother takes (she formerly took Shaklee for 20 years). However, once again, this is an endorsement coming from someone who also sells the product, so while I feel it is the best product there (as does my mentor, Ian King, who introduced me to the product and business) I do encourage others reading this to their own research and due diligence to find what they feel is right for them.

Jeremy