What are the dangers of sugar, and if fruits contain mostly sugar, doesn’t that make them bad as well?
I flirted with calling this post “The Greatest Fat Loss Secret of All-Time, Part II” but in reality, this article has little to do with fat loss and lots to do about sugar. For those of you who haven’t read the site’s first blog post (The Greatest Fat-Loss Secret of All-Time), that article emphasized the idea that fat does not make you fat, but sugar does. The process is mediated by insulin, the hormone secreted in response to surges in blood sugar, which directly signals our fat cells to “feed,” get bigger, and in turn make us fatter.
Excess sugar is bad because it stimulates fat storage and therefore weight gain. The medical literature has also proven sugar to:
· Induce a cascade of normally stress-related biochemical events, triggering cortisol release (prevents weight loss) and thickening of the blood.
· Inhibit the immune system.
· Inhibit the production of leptin, a hormone pivotal in appetite regulation.
· Promote oxidative stress in the body.
· Fuel cancer cells and over time, promote the development of insulin resistance, and therefore type II diabetes.
The most common question I’ve received in response to that post is: If I am minimizing my carbohydrate intake and am no longer eating breads, grains, and starchy vegetables, I am left with fruits as my primary source of carbohydrates; all fruits have sugar in them, so doesn’t that defeat the purpose? Herein lies the conundrum.
First, let’s talk about the glycemic index. According to www.GlycemicIndex.com:
The glycemic index (GI) is a ranking of carbohydrates on a scale from 0 to 100, according to the extent to which they raise blood sugar levels after eating. Foods with a high GI are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels. Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, and have proven benefits for health. Low GI diets have been shown to improve both glucose and lipid levels in people with diabetes (type 1 and type 2). They have benefits for weight control because they help control appetite and delay hunger. Low GI diets also reduce insulin levels and insulin resistance.
Note that low-GI foods have values less than 55. The same site also provides a comprehensive and searchable database for most foods and their associated GI value. For example, a boiled white potato has a GI of 96; crushed peanuts have a GI of 7. Another free list of foods and their associated GI values is available at: http://www.southbeach-diet-plan.com/glycemicfoodchart.htm.
The take home message is that not all sugar is created equal, and foods contain different types and amounts of sugar. This results in different effects on the spike in our blood sugar. Foods with a high GI will promote insulin release and make us fat, while low-GI foods will not cause a blood sugar spike, will not cause an insulin surge and will not cause our fat cells to get bigger.
Secondly, let’s clarify what “sugar” is. All carbohydrates are made up of tiny molecules called monosaccharides or simple sugars. These molecules come in many different flavors, the most common being glucose and fructose. Both glucose and fructose are abundant in fruits and vegetables; honey, for instance, is predominantly composed of fructose. In fact, when your blood sugar drops dangerously low, the human body (the liver) maintains the ability to make glucose on its own, through a process called gluconeogenesis. Simple sugars are very easy for the body to digest, because the molecules are small and easily absorbed by our small intestine (the place where food goes after your stomach). Double sugars, or the disaccharides, are larger molecules and require some work by the enzymes in the small intestine in order to be absorbed. The most common double sugars are sucrose (table sugar) and lactose (in milk). Grains and root vegetables (i.e. potatoes, yams, cassava) contain huge amounts of starch: a very large molecule that requires quite a bit of work from our guts to be broken down and then digested. Fruits and non-root vegetables do contain starch, but in negligible amounts.
Thirdly, fructose as a molecule is very similar to glucose, but arranged in a different pattern. Fructose also raises blood sugar less than glucose, but fructose also boosts your appetite through the stimulation of a hormone called gherin. Naturally, fruits do contain fructose, with some (figs, mango, raisins, pears, watermelons, and apples) containing more than others (limes, prunes, guavas, raspberries, blackberries, cherries, strawberries, and grapefruit). Also, fructose is mainly metabolized by the liver, so eating too much of this sugar can burn out your liver and cause a host of other problems. Fructose lowers your HDL (good cholesterol), raises your LDL (bad cholesterol), and elevates uric acid, which causes system inflammation (bad), has deleterious effects on your heart (heart attack), kidneys, and brain (stroke).1
Fructose is a naturally occurring substance and is not toxic per se, but what is toxic are the massive amounts we unknowingly consume in our modern diet. A “safe” level would be a consumption of less than 20 grams per day, when all the adverse effects detailed previously are not observed. In fact, in the early 1900s (when obesity was not a problem), the average person ate approximately 15 grams of fructose daily. Today, that number is 54.7 grams per day and accounts for just over 10% of our total calorie intake.2
In particular, high fructose corn syrup (HFCS) truly is public enemy number one in the nation’s sugar dilemma. The food industry manufactures this from cornstarch via the cheap and toxic conversion of glucose into fructose, concentrating it, and then adding it as a sweetener. In fact, even if you thought you weren’t ingesting HFCS, many foods nowadays have it added to increase flavor and drive up consumption of more products—examples include baby formula (gasp), ketchup, pickles, jelly, bread, yogurt, and flavored water. In the USA, our largest source of fructose comes from sugar-sweetened beverages. One can of soda contains about 40 grams of fructose.
So, are fruits inherently bad? No. Do fruits contain some fructose? Yes. So, can you eat fruits? YES, but be mindful of your consumption and pay attention to your total sugar intake and your ingestion of fructose. Any internet search will show his tables as a pop-up, but Dr. Richard Johnson has a book titled The Sugar Fix that lists tables of fruits and their associated fructose content. The reader must be aware that fruits have the added benefit of being jam-packed with vitamins, minerals, antioxidants and phytonutrients that ameliorate the effects of fructose. Phytonutrients are especially helpful because they prevent disease, keep you alive longer, and rid your body of “junk.” If you’re looking for a shortcut and want to keep it real simple, just stick to berries and you’ll be fine.
I hope that clears it all up.
Finally, in light of everything stated, I will leave you with my own personal list of foods that no one should EVER consume, and should NEVER think about buying. In these examples, not only are their sugar loads and GI exceedingly high, but one serving will exceed an adult’s allocation of fructose for several days. Just imagine all the adverse health consequences if any of these are a staple of your diet and consumed frequently—think of it as buying poison, for yourself or your family:
· Soda (Including Diet)
· Fruit Juice
· Canned Fruit
· Sports Drinks
· “Nutritional” Bars
I know I have left some folks cringing and aghast with the list, but the truth must be disseminated. Enjoy.
Dr. C.H.E. Sadaphal
1 Adverse Effects of Dietary Fructose Gaby, AR. Altern Med Rev. 2005 Dec; 10(4) 294-306.
2 Dietary Fructose Consumption Among US Children and Adults: The Third National Health and Nutrition Examination Survey Miriam B. Vos, Joel E. Kimmons, Cathleen Gillespie, Jean Welsh, Heidi Michels Blanck Medscape J Med. 2008; 10(7): 160. Published online 2008 July 9.