Low Fat Milk And The Shifting Winds of Evidence Based Medicine.

Posted on | July 3, 2013 | 2 Comments

Mike Magee

Reversals in medical science are not uncommon. As new evidence emerges, old tenets are easily discharged, and new “pillars of truth” adopted. It’s a necessary process, but confusing both for those who deliver care and those who receive it.

Nutritional science is a perfect example of the phenomenon. Back in 1995, excess fat consumption was felt to be central in increasing levels of obesity nationwide. As a result, we saw low fat recommendations explode and the marketplace adjust food and beverage formulas to advantage their bottom lines.(1)

By 2009, weight scales were exploding everywhere, and scientists took a second look at sugars and didn’t like what they saw.(2)

First, a primer on dietary sugars with a special focus on high fructose corn syrup:

Sugar is not a chemical term. It’s a common word which describes a group of sweet flavored carbohydrates. Glucose, a simple sugar that provides energy for human cells and is central to plant photosynthesis, derives its name from the Greek word gleukos (γλυκύς) meaning sweet. (3)

Another sugar with a long history in this country is sucrose, or table sugar, which comes from sugar beets and sugar cane. About 150 million tons of this molecule are produced worldwide each year.(4)

A third sugar, fructose, derives from fruits and honey, and is a component of sucrose.

GLUCOSE

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SUCROSE

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FRUCTOSE

High fructose corn syrup (HFCS) is not a crystal but rather a man-made liquid. First produced on a large scale in Japan in the late 1960’s, it begins with corn which is crushed and ground into a corn starch which is then liquified. The resultant mixture is almost entirely glucose. Enzymes are added which convert most of the glucose to fructose. The syrup produced is now 90% fructose and labelled HFCS 90. This is diluted with pure glucose corn syrup to create two very common mixes. HFCS 55 is 55% fructose and 45% glucose, and used mostly in soft drinks. HFCS 42 is 42% fructose and 58% glucose and primarily used in processed foods including breads, cereals, lunch meats, yogurt, and condiments. (5,6)

Shortly after the introduction of HFCS, manufacturers in the US turned their back on sucrose or table sugar as a primary sweetener for their products. Why? Cost and convenience. The price of sucrose in the US was roughly twice that of other countries as a result of quotas and tariffs imposed in 1977 that protected US producers. Combine this with the fact that corn production in the US has been heavily subsidized leading to cheap corn byproducts like HFCS, and that HFCS is a liquid product more easily transported then crystalline sucrose, and the stage was set for a rapid market shift.

In the U.S. It began in earnest in 1984 when Pepsi and Coca-Cola made the shift. Food processors quickly followed suit. Prices for HFCS remained low thanks to continued subsidies fueled by heavy lobbying from big corn producers like Archer-Daniels-Midland. The net effect was a rapid decline in the use of sucrose as a sweetener, which accounted for only 3.7% of the caloric sweetener in US beverages by 2005.(7)

By 2010, HFCS was rapidly becoming the next trans-fat in the public eye – a beverage and processed food transported sweetener that some believed was single handedly converting healthy kids into type 2 diabetics. In response to public concerns, manufacturers began to inch back to good old sucrose.(8)

But this week, evidence based reports sounded warning sirens all over the place. First, a study looking at the risk/benefit ratios of glucose and fructose in JAMA came to this conclusion: “The recommendation to replace fructose with glucose lacks an evidence basis. Rather, public health efforts should focus on reducing intakes of all highly processed carbohydrates, not just refined sugar.”(9)

On the heels of this shift, JAMA Pediatrics sounded the alarm on the holiest of all childhood beverages, milk. Some historical perspective from the authors:

“ In light of research linking sugar-sweetened beverage consumption to obesity, the US Department of Agriculture, the American Academy of Pediatrics, and other organizations have formulated recommendations on healthy beverages. These guidelines consistently recommend limiting consumption of all calorie-containing liquids, except reduced-fat milk, of which people in most age groups are encouraged to consume 3 cups daily.”(10)

What many did not appreciate however was that there was no real evidence that substitution of whole milk with low fat milk decreased obesity. Furthermore, manufacturers compensated for the decreased taste profile of low-fat milk for children by sweetening the milk with HFCS laden flavored syrups. These concoctions became staples of school lunch programs and offerings in school beverage machines. The net effect of switching from a cup of whole milk to a cup of sweetened low-fat milk was to lose 3 grams of fat but gain 13 grams of sugar.(10)

The evidence reported this week in addition questions the value of milk in general, especially with proper diets. Here’s what they say:

“Humans have no nutritional requirement for animal milk, an evolutionarily recent addition to diet. Anatomically modern humans presumably achieved adequate nutrition for millennia before domestication of dairy animals, and many populations throughout the world today consume little or no milk for biological reasons (lactase deficiency), lack of availability, or cultural preferences. Adequate dietary calcium for bone health, often cited as the primary rationale for high intakes of milk, can be obtained from many other sources. Indeed, the recommended levels of calcium intake in the United States, based predominately on balance studies of 3 weeks or less, likely overestimate actual requirements and greatly exceed recommended intakes in the United Kingdom. Throughout the world, bone fracture rates tend to be lower in countries that do not consume milk compared with those that do. Moreover, milk consumption does not protect against fracture in adults, according to a recent meta-analysis.”(10)

“Nevertheless, milk provides significant amounts of protein and other essential nutrients and may confer health benefits for children and adults with poor overall diet quality. For those with high-quality diets (including green leafy vegetables, legumes, nuts, seeds, and adequate protein), the nutritional benefits of high milk consumption may not outweigh the negative consequences.”(10)

So what’s the consumer to do in the face of shifting evidentiary sands?

A few common sense principles: 1) Liquids hide and transport calories. Drink water whenever possible. 2) Manufactured=Processed=Additives. Eat natural whenever possible and prepare your own food at home. 3) Truth in advertising? No such thing. Develop a relationship with several trustworthy online health sites, and frequent them often. Knowledge changes often, but you needn’t be the last to know about it.

For Health Commentary, I’m Mike Magee

References:

1. Hill JO, Prentice AM. Sugar and body weight regulation. Am J Clin Nutr. 1995;62(1)(suppl):264S-273S. http://www.ncbi.nlm.nih.gov/pubmed/7598083

2. Johnson RK, Appel LJ, Brands M, et al; American Heart Association Nutrition Committee of the Council on Nutrition, Physical Activity, and Metabolism and the Council on Epidemiology and Prevention. Dietary sugars intake and cardiovascular health: a scientific statement from the American Heart Association. Circulation. 2009;120(11):1011-1020. http://www.ncbi.nlm.nih.gov/pubmed/19704096

3. Merriam Webster Dictionary Online. http://www.merriam-webster.com/dictionary/glucose

4. Ulmann’s Encyclopedia of Industrial Chemistry.

5. The Health Effects of High Fructose Syrup, Report 3 of The Council on Science and Public Health (A-08)

6. Hanover LM, White JS. 1993. Manufacturing, composition, and applications of fructose. Am J Clin Nutr 58(suppl 5):724S-732S.)

7. Pollan M. Omnivore’s Dilemma. http://michaelpollan.com/books/the-omnivores-dilemma/

8. Magee M. Is high fructose corn syrup becoming the next trans-fat. https://www.healthcommentary.org/?page_id=3717

9. Ludwig D.S. Examining the health effects of fructose. JAMA. 2013;310(1):33-34. http://bit.ly/17IsHok

10. Ludwig D.S. and Willett W.C. Three Daily Servings of Reduced-Fat Milk. JAMA Pediatrics. July 3, 2013.http://archpedi.jamanetwork.com/article.aspx?articleid=1704826

Comments

2 Responses to “Low Fat Milk And The Shifting Winds of Evidence Based Medicine.”

Eric Triffin
July 24th, 2013 @ 8:18 am

Good info on refined sugars and the unnecessary use of milk. Good to quote the Harvard study on that.
Mike Magee
July 24th, 2013 @ 12:00 pm

Thanks, Eric. Appreciate your feedback. Mike