January 27, 2014

252 Some Positive Nutrient Studies [27 January 2014]

Over the last few weeks I have explained why flawed nutrient intake studies can show little or no benefit. Rather than belabor the point further (and I could, discussing dosage, nutrient form, etc) this week I am listing some of the hundreds of studies that have shown benefit from nutrient supplementation. This is just a small sample:

• A UCLA study in 1990s, with 11,000 men over 10 years found that 800 mg daily vitamin C reduced cardiovascular mortality by 42%, adding an average 6 years to their life.
• The Physician’s Health Study II found that taking a multivitamin was associated with reduced risk of death, over 11 years, of 12% from cancer and 39% from heart attacks.
• Supplementation in Vitamins and Mineral Antioxidants Study found a 31% reduction in total cancer incidence in men taking a multivitamin.
• A 2013 study of 77,446 adults found an inverse relationship between dietary selenium and the risk of pancreatic cancer.
• A 2007 study of 81,184 people found low B6 intake associated with an increased risk of colorectal cancer.
• A 2012 study on 23,943 people found that taking an antioxidant multivitamin reduced the risk of death from cancer by 48% and from any cause by 42%.
• A 2009 German study found that vitamin D3 supplementation reduced the risk of falls by 27% (more on this next week)

Note that some of these are “observational studies” that discover a relationship but do not necessarily show cause and effect. But when random controlled prospective studies fail to show the expected results, the researchers should first look for possible causes before concluding that supplementation is useless.

“Are Multiple Vitamins and Minerals Really Worthless?” unpublished article by Dr. Zoltan P. Rona
Call to clinicians: Report vitamin D data by John Cannell, MD 20 Jan 2014

For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.

January 20, 2014

251 Nutrient Co-Factors [20 January 2014]

Last week I explained how the unique features of the dose-response relationship for nutrients can skew the results of nutrient intake studies towards showing no benefit. Another reason why nutrient studies often find little or no benefit is that adequate levels of cofactors are rarely ensured. Unlike drugs, nutrients work better together, and often don’t work at all without certain others. To accurately test the effect of a single nutrient on a particular process (eg bone-building), all the other nutrients required for that process must be adequately available. For example, to test the effect of calcium supplementation, all the other nutrients required for bone building must be available in adequate amounts: vitamin D, vitamin K2, magnesium, protein, and certain B vitamins. Without ensuring adequate levels of these co-factors, the study results will be meaningless and misleading.

Most nutrient studies are designed following the drug model which attempts to eliminate the effect of all other variables. But instead of eliminating the effect of cofactors by ensuring adequate levels, they are too often simply ignored. The results may be accurate for what is actually being tested – e.g. that calcium supplementation alone does not significantly increase bone formation, but to conclude that calcium is worthless would be erroneous. Instead, further studies are required to determine the optimum levels of each of the other co-factors.

The failure to consider cofactors, along with the location on the dose-response curve discussed last week, is likely responsible for the “equivocal and sometimes contradictory” vitamin D trials referred to in the Editorial “Enough is Enough: Stop Wasting Money on Vitamin and Mineral Supplements” (J Annals Int. Med, 17 Dec 2013). In one sense I agree with the authors of this editorial when they state “…further large prevention trials [of vitamins] are no longer justified.” Conducting more poorly-designed nutrient trials that are incapable of testing what they purport to be testing would not only be a waste of time and money but their erroneous conclusions may dissuade many from actions that might improve their health.

Source: Robert Heaney – Some Rules for Studies Evaluating Nutrient Effects

For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.

January 13, 2014

250 The Nutrient Dose-Response Curve [13 January 2013]

Last week I discussed a medical journal editorial which claimed that supplements don’t work and are just a waste of money. I ended by introducing the nutrient paradox – how it can be that nutrients, by definition essential for life, frequently show little benefit in supplement studies. This week I will examine some of the reasons for this paradox.

Robert P. Heaney, MD, a world-renowned endocrinologist specializing in bone, calcium & vitamin D physiology, published an article in June 2013 titled “Some Rules for Studies Evaluating Nutrient Effects” which explores some reasons for this paradox.

Heaney first looks at the dose-response relationship for nutrients which shows a sigmoid (S-shaped) curve when graphed. At low intakes there is no observable effect – there just isn’t enough to do the job. Then at higher intakes there is a strong response to increased dose. Finally at some level the curve flattens again and there is no additional benefit from taking more. Unlike drugs, any nutrient being studied will already occur at some level in the participants. The key is to know where on the curve the study population lies. In the case of the elderly physicians study mentioned last week, it’s likely that they were well-nourished with few deficiencies, so would be less likely to benefit from a multivitamin. This conclusion however cannot be transferred to other populations. The Women’s Health Initiative trial which found little to no benefit from calcium supplementation fell into a similar trap because the participants were already at or above the recommended level of calcium intake. Heaney asks, with apparent frustration, why this flawed study is still being quoted.

Heaney also explains that the middle section of the curve where increasing dose increases benefits is generally much narrower for nutrients than for drugs, meaning there is a smaller range of intake that will show a particular effect. Nutrient studies will not detect any benefit outside of this narrow range which is approximately 1 order of magnitude (10x difference from the lowest to highest) for nutrients, compared to 2 or even 3 orders of magnitude (100x to 1000x) for drugs.

And because the curve is not linear (a straight line), pooling data from studies with different doses, different participant base levels, and/or different durations (length of study) will produce confusing, misleading results. The first study mentioned last week was one of these.

For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.

January 6, 2014

249 Multivitamins – a Waste of Money? [6 Jan 2014]

Did you see any of the news headlines a few weeks ago like “Multivitamins a waste of money” or “Vitamin, mineral supplements offer no benefits”? These were newspaper reports of an editorial in the December 17 Annals of Internal Medicine which was commenting on three studies published in the same issue. The first was a review of 27 trials of single or paired vitamins which found no clear evidence of benefits on all-cause mortality, cardiovascular disease or cancer. The second was a large 12 year controlled study of elderly physicians which found no difference in cognitive decline between multivitamins and placebo. The third found no significant difference in recurring cardiovascular events (heart attack) with the use of a “high dose 28-component multivitamin”.

Based on these three studies, with vague reference to previous research with similar results, the editors concluded that effects – either beneficial or harmful – of multivitamins are too small to be detected with such small trials and, while conceding that there may be small benefits or harms in a small subgroup of the population, conclude that the “case is closed” and “…vitamins should not be used for chronic disease prevention.” The editors go beyond that, warning about certain harmful vitamins and even describing vitamin D studies (which have shown clear strong benefits in many different health areas) as equivocal and contradictory. What surprised me most though was their call to halt research: “…large prevention trials are no longer justified…” which scientists almost never do. Journalists (and their editors) with little science and no nutritional expertise then take these opinions (which is what an editorial really is) and run with them, concocting the misleading headlines, with accompanying articles, mentioned above.

This editorial raises so many important issues that it will require several columns for an adequate response. Next week I will discuss the nutrient paradox – how it can be that nutrients, by definition essential for life, frequently show little benefit in supplement studies. In later columns we’ll examine the three above-mentioned studies in more detail. Stay tuned! By the way I am still taking my vitamins.

For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.