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Vitamin Supplements May Increase Risk of Disease

Vitamin Supplements May Increase Risk of Disease

Many people pop a morning multivitamin as a very personal form of "health insurance." We figure that just in case our diet isn't adequately providing for our nutritional needs, we'll take a multivitamin to be safe. Some of us take it a step further, adding specific vitamins in the belief that "more is better," hoping to avoid certain diseases in the future. And whether we do or don't add a vitamin pill to our morning routine, many of us wouldn't hesitate to drink down a beverage which has been fortified with large doses of vitamins and minerals. We hardly notice that we may already be consuming excess doses of vitamins in the form of fortified cereals or products made from fortified flour. Unfortunately, adding extra amounts of micronutrients isn't as healthy or as safe as we might believe. Research is showing us that diseases like obesity, heart attack or stroke, and some cancers may be linked to over supplementation.

Excess Vitamin Intake Linked to Obesity

Dubbed "the vitamin paradox," researchers are finding that obesity rates are linked to excess vitamin intake, particularly excess B vitamins. The authors of a study published in the World Journal of Diabetes in 2015 state, "Given that there is a correlation between high vitamin intake and the increased prevalence of obesity, it can be assumed that obesity could be one of [the] manifestations of chronic vitamin poisoning." 

In a study published the previous year, the research team looked into the sources of vitamins and the effect of supplementation on societies. They wrote that until the mid 1930s, vitamins were obtained solely through food intake. The type and amount of vitamins available to eat fluctuated by seasonal availability of foods, but this posed no significant problem. Since our bodies are adapted for vitamin homeostasis, we either sweat out or store vitamins as needed. That's why it takes several months of vitamin C deprivation before symptoms of deficiency manifest.

The researchers note that over the past few decades, our intake of vitamins has been consistently and significantly higher than the estimated daily average requirements. They attribute this excess intake to:

• Year-round access to fresh fruits and vegetables. Due to advances in shipping and storage of produce, we are getting more vitamins from fresh foods all year long.

• Increased consumption of animal products. In the past few decades, the trend has been toward a more meat-centric diet. This has raised the intake of certain vitamins, particularly nicotinamide (a form of the B vitamin niacin). Between the 1930s and 2000, the U.S. consumption of nicotinamide increased from 6.8 mg to 11.4 mg.

• Fortified foods and vitamin-enriched drinks. Flour products, cereals, infant formula, and many sweetened beverages are fortified with synthetic vitamins. "Notably, ready-to-eat cereals are a major vehicle of fortification of B vitamins (B1, B2, B6 and niacin). ... The levels of vitamins in fortified ready-to-eat cereals are so high that consumption of less than a quarter pound of them (because foods per se also contain some amount of vitamins) meets the daily need for these vitamins in an adult."

The combination of these factors has led to a significant increase in vitamin intake over the past few decades. The per capita consumption of vitamins B1, B2, and niacin in the United States doubled from the 1930s to 2000.

The study shows that as countries introduce fortification of foods, particularly fortification with B vitamins, obesity increases. The fact that modern lifestyles decrease the need for energy expenditure may be complicating the effect of excess vitamins. Without energy expenditure, there is less opportunity to sweat out the extra vitamins, which leads to obesity.

While obesity is a significant concern for all races, the researchers hypothesize that this combination of excess vitamins and decreased need for energy expenditure may be of particular concern for black people. They explain that "the activity of sweat glands of blacks is lower than that of whites in the same temperature environment. There is evidence showing that black women may have lower levels of physical activity than black men. This may explain why obesity prevalence is greater in blacks, especially black women, than in whites in the United States." The CDC reports that obesity rates are 47.8% for blacks, 42.5% for Hispanics, 32.6% for whites, and 10.8% for Asians. 

Calcium Supplements Linked to Heart Attack and Stroke

Multiple studies published by a team of researches led by Mark J. Bolland, PhD, indicate that while evidence for calcium supplementation to prevent bone fracture is "weak and inconsistant," there is definately a small but significant increase in the risk of heart attack and stroke when taking calcium supplements. In a randomized controlled trial, 1,471 postmenopausal women were given either calcium supplements or a placebo. After five years, it was found that the women taking the calcium supplements had a higher rate of cardiovascular events.  A meta-analysis published in 2010 included 15 clinical trials for a total of 12,000 participants. Calcium supplementation was found to increase the risk of heart attack by 30 percent. In 2011, the team revisited data from the Calcium and Vitamin D Supplementation Study from the Women's Health Inititive. This radominzed, placebo controlled trial followed 36,282 postmenopausal women during a seven year period. In this study the authors found that risk of heart attack increased 25 to 30 percent and risk of stroke went up by 15 to 20 percent.

Vitamin E and the Prostate Cancer Connection

"Given that [a 2005 study found] more than 50% of individuals 60 years or older are taking supplements containing vitamin E and that 23% of them are taking at least 400 IU/d17 despite a recommended daily dietary allowance of only 22.4 IU for adult men, the implications of our observations are substantial," write the authors of a study based on the the Selenium and Vitamin E Cancer Prevention Trial (SELECT). The results of SELECT were alarming enough to end the study early. 

Although previous trials had indicated that the supplements might protect men from cancer of the prostate, this randomized controlled trial which enrolled over 35,000 men found the opposite. The incidence of new prostate cancer cases increased by 17 percent in the men taking 400 IU of vitamin E supplements daily. The researchers conclude that the result of their trial "demonstrates the potential for seemingly innocuous yet biologically active substances such as vitamins to cause harm." 

Unfortunately, the authors had to acknowledge that their trial was not the first to find harm to participants as a result of vitamin supplementation:

Moreover, the increased incidence of prostate cancer seen in SELECT, the previously reported increased incidence of lung cancer with high-dose beta carotene in both ATBC and the Beta-Carotene and Retinol Efficacy Trial (CARET), and the increased risk of colon polyps seen in a trial administering high-dose folate, suggest that caution should be used when recommending or studying high doses of micronutrients.

The authors speculate that unlike synthetic pharmaceuticals, vitamins, though a natural part of the human diet, may be equally as harmful in excess as they are in deficiency. The researchers also caution that based on the follow-up evidence done with SELECT participants, the effects of excess micronutrients can have implications on health long after supplementation has ceased.

The Follies of Folic Acid Supplementation

Vitamin B9 is is also called folate (which is the naturally occurring micronutrient) or folic acid (which is a synthetic vitamin manufactured to supplement our diet). Often, unfortunately, both the public and medical professionals mistakenly use the term "folate" to describe both naturally-occurring folate or synthetic folic acid. The distinction between them, however, is very important.

Deficiency in folate is a risk factor for heart disease, stroke, and cancer. But it was folate's role in preventing birth abnormalities such as neural tube defects (NTD) that brought it to the public's attention. A baby's neural tube closes by the end of the fourth week of pregnancy, a time when most women — even those who are  planning their pregnancy — do not even know they are pregnant. The U.S., like several other countries, now mandates that flour, pasta, and other grain products be fortified with folic acid to prevent defects such as spina bifida. While the rates of NTD have fallen with mandatory supplementation, other countries such as Finland, France, Sweden, Singapore, and Taiwan believe that a healthy diet which includes adequate amounts of folate may be enough, and thus do not encourage supplementation. Natural sources of folate include leafy green vegetables, asparagus, broccoli, cauliflower, beets, and legumes.

Unlike the clear benefits seen with adequate folate intake from whole food sources, there are questions about the safety of supplemental folic acid. No causality between folic acid and disease has been firmly established, so at this time government-mandated fortification continues. Since mandatory folic acid fortification began in Canada and the United States in 1998, there has been an increase in the rates of colorectal cancer. Researchers hypothesize that fortification of grains is indeed related to this increase.

A randomized clinical trial was conducted with just over 1000 participants with a recent history of colorectal adenomas (benign tumors in the lining of the colon which are precursors to cancer), but no history of colon cancer. After six years of supplementation, the study authors found a significant increase in the incidence of non-colorectal cancer, particularly prostate cancer, in the group who were given the folic acid supplements. In the conclusion, the researchers said that although folic acid supplementation had been expected to have a protective effect against further colorectal adenomas, no such protection was seen. "Indeed," they wrote, "there was a suggestion of an increase in risk for advanced lesions and in adenoma multiplicity among those participants randomized to the folic acid group."

Norway is one of the countries which doesn't fortify foods with folic acid. Researchers in that county gave heart-failure patients supplemental folic acid and vitamin B12. The participants receiving the supplements demonstrated a significant increase in cancer diagnosis and all-cause mortality, driven mainly by an increase in lung cancer. In fact, folic acid supplementation doesn't seem to have any benefit for heart patients. Researchers conducted a meta-analysis of 12 randomized controlled trials to determine the effect of folic acid supplementation on cardiovascular disease. They found that "folic acid supplementation has not been shown to reduce risk of cardiovascular diseases or all-cause mortality among participants with prior history of vascular disease." 

While research indicates that folate intake from whole foods is associated with lower incidence of breast cancer, supplemental folic acid may increase the risk of breast cancer in postmenopausal women. 

When Supplements are Necessary

Many of my patients are interested in doing what they can to optimize their health. When they ask about what types of supplements they should routinely include, I talk to them about their diet. Low-fat, whole plant foods and sunshine are the absolute best source of all the nutrients we need. They have the macronutrients, micronutrients, antioxidants, and phytochemicals required for healing and vibrant health. Unlike expensive vitamin pills, the nutrients in whole plant foods come packaged together synergistically so that we get the biggest nutritional bang for our buck. Even the "quality" vitamins made from "whole foods" are merely highly processed foods mixed together very differently from the way nature designed them. 

Instead of recommending supplements right away, I order blood work done on my patients so that we can establish their current state of health. If after examining the lab results we find a deficiency, then we discuss the best way to bring that nutrient up into the normal range. Sometimes, I suggest changes in diet; other times a supplement may be a better option. For example, vitamin B12 (as hydroxycobalamin) is a supplement I regularly recommend. And since about 75 percent of the population doesn't get adequate sunshine in order to manufacture sufficient vitamin D, I also find myself regularly recommending supplements of vitamin D3 in the vegan form. 

For a detailed discussion on how and when to supplement, I recommend an article by Jeff Novick, MS, RD. Follow the hyperlink to his article entitled "Supplement Recommendations" to read a thorough summary of a whole foods approach to supplementation.

Our culture has become obsessed with isolated nutrients, and many of us have developed misguided thinking with regard to them. T. Colin Campbell, PhD with Howard Jacobson PhD, have written a book entitled "Whole" which examines the history of our infatuation with isolated nutrients and looks at the effect that this nutritional mindset has on our health. Dr. Campbell writes, "You may find it hard to swallow the truth of the ineffectiveness and potential harm of supplements. Arguably, the supplement industry has been even more effective in spreading their propaganda than the pharmaceutical industry. After all, supplements are 'natural'; they are the same nutrients you find in food. ... But there's nothing natural about consuming these nutrients in isolation. And the main issue is not whether you like the marketing of natural pills, but what effects these vitamins and related supplements have on your long-term health."

I invite you to "supplement" your diet with more low-fat vegetables and legumes. Fruits and intact whole grains also have a role to play. Raw nuts and seeds, on a limited basis, may be used by some if they don't include added oil or salt. The World Health Organization advises that all people over the age of fifty, regardless of diet style, use vitamin B12, which is only made by bacteria, not by plants or animals. Lab tests can reveal if any supplements beyond that are necessary. 

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