Week 10: What the Fructose?

There were some surprises in various foods and their effect on blood sugar that we talked about last time. Being aware of these surprises is crucial to having a good mix of foods. The general rule was that starches and sugars converted quickly into sugar and that vegetables and fruit are converted more slowly. For metabolically-damaged people this is important.  

So does understanding how fruit turns slowly into sugar in the blood mean that one should eat a lot of it? To answer this question one needs to study how the body converts fructose into energy. Alcohol, sugar alcohol, and fructose are taken to the liver and changed there into a type of fat, a triglyceride. (Sugar alcohol is a product often found in diet foods as it does not affect blood sugar and is regard by many as a free carbohydrate. I was always suspicious of this idea. Sugar alcohols are often found in low carb productions like diet bars and in some dietetic ice cream.) Note that individual cells can convert these items into sugar directly, but as a general rule it is the liver that does the "heavy lifting." This is why alcoholics often destroy their liver by overwhelming it with alcohol. The dosage is the poison, so a little of these products should not be a problem, unless your triglycerides are too high. Hopefully you have had your blood work done and you know how high your triglycerides are. 

When I began my quest for personal health, mine were crazy high at 268. Now they are at an "acceptable" 110. Several factors are involved in your triglyceride levels. If you a overweight then they will be higher than they should be. Losing weight by any means will reduce them. But ironically, losing weight will drop more triglycerides into your blood as you lose weight and your body burns your fat. So in the short run as you lose weight your triglyceride level should be monitored but not a high priority for intervention.  

So for me the answer to the question as to how much fruit, alcohol, and sugar alcohol one should eat depends on the level of triglycerides in the blood. If your level is over 150, the standard consensus level for danger, then one should be greatly limiting these items in your diet. There is considerable debate about what the best level of triglycerides is. Some want it to be less than 100. This is my personal goal. So as a result of this I try to limit my alcohol, fruit, and sugar alcohol consumption to one serving in total a day. This is usually some berries in the morning, although I have been known to have an adult beverage in the evening in addition to this. 

So our goal for this week is to consider how much we are eating that our body is turning into fat flowing in our bloodstream. Remembering that the dosage is the poison, have yourself tested to determine how much of these foods you need to be eating. If your triglycerides are more than 150, you need to consume very little to none. If you are in the 100 to 150 range then you need to limit your intake to one or two servings a day. If less than 100 then this does not seem to be a problem for you and you can consume more. Be sure to periodically retest your levels. And no, you cannot have your weekly allotment of alcohol all at once. 

The homework this week is a presentation by one of the main "fructose is evil" advocates, and my critique of his ideas from a previous blog post. 

I think he is greatly oversimplifying. Looking at other interviews he has done, he said that carbohydrate and fat cannot exist in the same food. This is really strange, because they do. To make the details of what he is proposing even more confusing, he said that fruits are all right because they have fiber. Well, that depends on the fruit. Bananas have little fiber.

Even vegans like Dr. McDougal recognize that fruits can play a negative role in the formation of triglycerides, which are associated with heart disease. More discussion of this would have strengthened Lustig’s case.

He also said in the video that early humans ate 100 to 300 grams of fiber a day. That is rather high. Most estimates I have read place it at 100 grams. The only way they got this much was that ancient foods had not been artificially selected to make them sweeter and have more carbohydrates.

The recommendation is that humans should consume 25 grams. The average in America today is 12. Obviously there is room for improvement. Today I ate 55 grams of fiber, 15 of it artificial from a protein bar. How did I get the other 40 grams naturally? I ate a grapefruit, a banana, an apple, and one cup of strawberries. I also ate 3 cups of Brussels sprouts and three cups of various types of lettuce. I also got fiber from nuts. I had some spinach and beans with my fish. With this huge fiber feast, I still only got 40 grams of fiber. To approach what our ancestors ate may not be practical. (For those curious I am trying various dietary combinations to see how I feel. Note that I am not eating that much fruit now but I am still getting a lot of fiber from vegetables.)

So while I have some reservations about Dr. Lustig's presentation due to oversimplification of complex issues, the reminder of the dangers of fructose is something that needs consideration. I doubt I will eat as much fruit as I did today on a regular basis. That seems like too much fructose. Lustig's explanation of fructose metabolism makes that clear to me.

Here is how Gary Taubes, no friend to sugar, describes "The Bitter Truth About Sugar" in the NY Times:

It doesn’t hurt Lustig’s cause that he is a compelling public speaker. His critics argue that what makes him compelling is his practice of taking suggestive evidence and insisting that it’s incontrovertible. Lustig certainly doesn’t dabble in shades of gray. Sugar is not just an empty calorie, he says; its effect on us is much more insidious. “It’s not about the calories,” he says. “It has nothing to do with the calories. It’s a poison by itself.”

Taubes presents a much more balanced approach, I recomend the whole article he wrote as a supplement, or substitution, to this viral video. 

So I am suggesting that during a perioid of weight loss that one needs to limit the fruits, alcohol and sugar alcohol one eats as this tends to raise triglycerides.