Carbohydrates

Scientific studies (review articles) on the relationship between carbohydrates and disease prevention:
One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

1. Resistant starch type 2 improves residual renal function of patients under maintenance hemodialysis
2. Carbohydrate dietary intake may decrease esophageal cancer
3. Carbohydrate intake does not increase risk of fracture
4. Dietary salt intake increases risk of esophageal cancer
5. 50 g/d carbohydrates increase good cholesterol in overweight/obese adults
6. Carbohydrate intake increases metabolic syndrome
7. All-cause mortality risk is lowest with a diet with 50-55 En% carbohydrates
8. No association between carbohydrate intake and prostate cancer risk
9. High sucrose intake might increase the risk of Crohn’s disease
10. Intensive glucose control slows down cognitive decline in persons with type 2 diabetes
11. Low-carbohydrate diets decrease LDL particle number
12. Low carbohydrate diet decreases type 2 diabetes
13. Diet with 30 En% carbohydrates causally increases adiponectin concentration in adults
14. A diet of below 45 En% carbohydrate during 3 to 6 months reduces HbA1c level of patients with type 2 diabetes
15. Higher dietary carbohydrate intake increases colorectal cancer risk in men
16. A high GL diet is a risk factor of stroke events
17. Low-GI diet is good for patients with type 2 diabetes
18. A diet with low GI increases metabolic syndrome
19. A low GI diet decreases LDL-cholesterol
20. It is probably better to consume a low-glycemic-index carbohydrate meal before endurance performance

• Carbohydrates (saccharides) are divided into monosaccharides, disaccharides, oligosaccharides and polysaccharides.
• Monosaccharides and disaccharides are also called bad sugars or simple sugars.
• Monosaccharides and disaccharides, such as glucose, maltodextrine and fructose are rapidly absorbed in the blood stream and thus giving the body in a short time energy. Therefore, they are often added to sports drinks.
  Simple sugars are sweet to the taste and therefore, are often added to industrial foods.
• Oligosaccharides (raffinose, lactose, fructose and sorbitol) can cause intestinal gas.  Raffinose is found in cabbage, Brussels sprouts, broccoli, asparagus, whole grains and beans.
  Humans don't have all of the necessary enzymes required to break down oligosaccharides into monosaccharides or disaccharides, leading to undigested sugars entering the large intestine.
  The bacteria that live in the large intestine break down the oligosaccharides. This produces the gas that must eventually come out of the rectum.
• Oligosaccharides and polysaccharides are also called complex sugars. They are not sweet to the taste.
• Carbohydrates are the main energy source of the human body, especially for the brains, muscles and red blood cells (=responsible for the red color of blood).
• A special kind of polysaccharides is dietary fiber.
• Dietary fibers cannot be absorbed in the small intestine and therefore they cannot provide energy (=also called calories).
• Dietary fiber cannot be used as energy source in the human body.
• Dietary fiber can be divided into soluble and insoluble fiber.
• Dietary fibers prevent constipation, lower cholesterol, reduce the risk of getting colorectal cancer and are necessary for healthy intestinal functions.
• Eat daily 2-5 servings of fruit and 300 grams vegetables to obtain sufficient dietary fiber (25-30 grams).
  25 grams fiber per day corresponds to a diet with at least 1.3 grams fiber per 100 kcal.
• The RDA of carbohydrates is 5-7 grams per kg body weight.
• The human body uses daily at least 160 grams of glucose, of which 120 grams are used by the brains.
  At an amount of 180 grams of glucose per day is not necessary to synthesize glucose from amino acids.
• The term glycemic index is been used because a food item with a high content of polysaccharides does not always give a slow absorption.
• The glycemic index (GI) is a measure of the effects of carbohydrates on blood sugar levels.
• A food item with a high content of monosaccharides and/or disaccharides is quickly absorbed, causing a quick rise on the blood sugar level. In other words, a food item with a high content of monosaccharides and/or disaccharides has a high glycemic index number.
• A food item with a high GI number (GI-number of 70 or higher) is bad for the human body because it causes big fluctuations in the blood glucose level.
  Big fluctuations in the blood glucose level increase the risk of developing diabetes, heart disease and obesity.
• A meal with a low GI number (55 or lower) provides a longer feeling of satiety (=thus less mealtime moments during the day) than a meal with a high GI number (70 or higher).
• A food item with a GI number of 55 or lower is called low.
  A food item with a GI number of 70 or higher is called high.
• A good breakfast (with products with a low GI number) will bring the fasting blood glucose level to the desired value of 5.5 mmol/L.
• The body’s carbohydrates are stored as glycogen. The glycogen content of the human body is composed of 150 grams in the liver + 250 grams in the muscles.
• 400 grams of glycogen is equivalent to 1600 calories because 1 gram of glycogen provides 4 kcal or 17 kJ.
  3 grams of water are stored together with every gram stored glycogen. Thus, 400 grams of glycogen give 1-2 kg weight gain.
  400 grams of glycogen are sufficient for:
  • 30 minutes vigorous physical exercises or
  • 45-90 minutes of team sport or
  • 60-90 minutes less intensive, more prolonged exercises, such as running and cycling or
  • 32 km long distance runs.

• Carbohydrate plays a key role in the performance of exercise lasting 60-90 minutes.
• Carbohydrate is the preferred fuel for high intensity exercise (performed at over 70% of aerobic capacity or VO2max).   
  Total carbohydrate use is highest at 85% VO2max.
  High-intensity exercise corresponds to 70-85 percent of the maximum heart rate.
• A general guideline for athletes is 55 En% carbohydrate or 5-7 grams of carbohydrate per kg body weight per day.
• The tapering off method is reducing the training frequency and increasing the carbohydrate intake 3 days before a contest. The carbohydrate intake during these 3 days is 7-10 grams per kg body weight per day.
• Power athletes and short distance runners need a lot of energy in a short time.
  This high energy need in a short time cannot be supplied by fat burning (fat oxidation) because fat burning is a slow process.
  This high energy need in a short time must be supplied by carbohydrate burning. That is why the body’s glycogen must be totally replenished after physical exercise. If not, the body has not enough glycogen for the next session of physical exercise. In that case the body will use protein as energy source, resulting in muscle degradation.
  Muscle degradation results in a lower resting metabolic rate (RMR).
  Thus, take enough carbohydrates after strength training!
• A diet with more than 70 En% carbohydrates will lead to a deficiency of proteins or fat.
• A balanced diet contains 45-70 En% carbohydrates, 10-25 En% simple sugars and at least 1.3 grams fiber per 100 kcal.
  The EFSA recommends daily 2000 kcal for women and 2500 kcal for men.