Sugar Substitutes: Health Benefits and Risks
The rising rates of obesity and associated health complications, such as diabetes, cardiovascular disease and some types of cancer, have led many consumers to look for alternatives to sugar to help control their blood glucose levels and reduce intake of calories. In response to this demand, scientists have developed a number of sugar substitutes. Sugar substitutes, also known as artificial sweeteners, are substances used to sweeten foods and beverages and serve as an alternative to table sugar (sucrose). They are typically many times sweeter than sucrose and thus can be used in smaller quantities to sweeten foods or drinks. Since they are used in relatively small amounts, they provide far fewer calories than table sugar.
Sugar substitutes can be divided into non-nutritive and nutritive sweeteners. Non-nutritive sugar substitutes provide little if any energy in the form of calories and do not affect blood sugar levels. Nutritive sweeteners do provide calories, but in lesser amounts than table sugar. They can, however, affect blood glucose levels, but do not require much insulin to be metabolized.
In the U.S., six non-nutritive sugar substitutes have been approved by the FDA:
- Acesulfame-K (acesulfame potassium) is about 200 times sweeter than sucrose and due to its long shelf life it is suitable for cooking.
- Advantame is 20.000 times sweeter than table sugar and is stable at high temperatures.
- Aspartame has a taste that is 200 times sweeter than table sugar. It is not heat stable and therefore not used in foods for cooking.
- Neotame is intensely sweet, about 8,000 times sweeter than sucrose. It is heat stable and can be used in cooking and baking.
- Saccharin is 300-500 times sweeter than sucrose. It is used primarily in soft drinks and as a tabletop sweetener.
- Sucralose is 600 times sweeter than sucrose. Due to its good shelf life and heat stability sucralose may be used in cooking.
In addition, three other non-nutritive sugar substitutes have been approved in various other countries but not in the USA. They are called alitame, sodium cyclamate and stevia. Alitame is 2.000 times sweeter than table sugar. It is more heat stable than aspartame but less than acesulfame-K, neotame, saccharin or sucralose. Cyclamate is between 30 to 50 times sweeter than table sugar and is stable under heating. While alitame does not appear to pose any safety risks, some older studies indicate that sodium cyclamate may promote cancer development once cancer has already appeared.
Stevia is an herbal sweetener extracted from the leaves of Stevia rebaudiana. It is 150 times sweeter than sucrose and heat stable. Because of safety concerns regarding its negative impact on metabolism and potential carcinogenicity, stevia may not be sold in the USA as a sweetener. However, it is generally available as a dietary supplement.
Health Impact of Non-Nutritive Sugar Substitutes
Generally, a sugar substitute may be approved for use only after it has been shown to be safe and effective. The amount of an artificial sweetener that is deemed safe by the FDA for daily use is referred to as its acceptable daily intake (ADI) and it is as follows:
Although some concerns have been raised about the potential safety of some artificial sweeteners, the FDA has found that these substances are safe when used as recommended. The only exception is aspartame, which contains the amino acid phenylalanine, and, therefore, may not be used by patients with phenylketonuria. Nonetheless, some other health concerns raised about individual sweeteners include the following:
Acesulfame-K. Skeptics claim that this sugar substitute produces tumors in rats. The FDA as well as the European Food Safety Authority (EFSA) dismissed such claims, stating that these tumors were not the result of acesulfame-K. Nearly 100 studies have shown acesulfame-K to be safe in humans, according to the FDA.
Aspartame. As it was mentioned earlier, this sweetener contains the amino acid phenylalanine, and, therefore, is not suitable for people who have phenylketonuria. In addition, people with advanced liver disease and pregnant women with high levels of phenylalanine in their blood may also have difficulty metabolizing aspartame.
Aspartame also contains aspartic acid, which has been associated with neurotoxic effects. However, according to the FDA, aspartic acid poses no threat to people who consume this substance at normal levels.
There is also some controversy about a possible link between the use of asparatame and leukemia. Two Italian studies reported that aspartame caused leukemia and lymphoma in laboratory rats. However, FDA officials, after having reviewed other relevant studies, maintain that aspartame is safe for use in humans.
Neotame. Although similar in chemical structure to aspartame, neotame does not release phenylalanine to the digestive system and is safe for people who have the inherited disease phenylketonuria.
Saccharin. Although saccharin was in the past (in the late 1970s) found to cause bladder cancer in laboratory rats, later studies have failed to confirm a link between saccharin use and cancer in humans. FDA officials maintain that saccharin does not pose a health risk to humans when consumed at normal levels. However, pregnant women should be careful with the use of saccharin because its molecule can cross the placenta and may remain in fetal tissues.
Sucralose. Since the body does not recognize sucralose as a carbohydrate (unlike sucrose), it passes through the digestive system without being broken down or absorbed and can be, therefore, used safely by diabetics.
Several studies have indicated that some artificial sweeteners may stimulate appetite, thus contributing to increased weight gain. However, most studies have found that sugar substitutes help people to lose weight or maintain their present weight level, if used in modest amounts and combined with regular exercise.
Sugar substitutes can benefit people with certain health conditions, such as patients with diabetes or those with high triglyceride levels (hypertriglyceridemia). People with hypertriglyceridemia are usually advised to cut back on sugary foods, especially if they are diagnosed with insulin resistance. Replacing sucrose with sugar substitutes may help them achieve this goal.
However, as it was mentioned earlier, pregnant women should limit their use of saccharin and those with high levels of phenylalanine in the blood should also avoid using aspartame during pregnancy.
Nutritive sweeteners (also referred to as sugar replacers) are often used as alternative sweeteners. The sweetness of nutritive sweeteners generally varies. They may be anywhere from 25-100% as sweet as sucrose. In contrast to non-nutritive sugar substitutes, nutritive sugar substitutes do provide calories, but in lesser amounts than sucrose.
Nutritive sweeteners do not promote tooth decay because bacteria do not convert them to acids. Also, they do not cause a sudden increase in blood sugar levels because molecules of nutritive sweeteners are absorbed slowly and incompletely and do not require much insulin to be metabolized. Hence, their effect on blood glucose levels is minimal. This makes nutritive sugar substitutes good alternatives to sucrose for people with diabetes.
Sugar alcohols (polyols) are the most commonly used nutritive sweeteners today. They add sweetness and bulk to various foods. Just like sucrose, polyols are carbohydrates and appear naturally in many fruits and vegetables. However, if consumed in excess, sugar alcohols may have a laxative effect. Examples of polyols commonly found in foods and beverages include isomalt, lacticol, maltitol, mannitol, sorbitol or xylitol.
It needs to be mentioned that sorbitol is also made in the human body and a condition called hyperglycemia encourages its formation. Since sorbitol has trouble passing through cell membranes, it may injure the cells. This damage has been linked to a number of conditions including diabetic retinopathy, cataracts, diabetic neuropathy and diabetic nephropathy. However, due to its poor absorption in the digestive tract dietary sorbitol is not believed to cause diabetic complications and, if used in moderation, can be safely consumed by diabetics.
Tagatose is a different type of nutritive sweetener. It is a monosaccharide similar to fructose and derived from lactose but with a minimal effect on blood glucose levels. In addition, it only has 38% of calories of sucrose. About 80% of tagatose is not absorbed until it reaches the large intestine, where bacteria finally break it down so that it can be absorbed by the body. Because of this difference in absorption compared with fructose or sucrose, glycemic index of tagatose is very low.
When used in reasonable amounts, nutritive sweeteners do not cause any discomfort. However, side effects can occur when consumed in large quantities. Symptoms may include flatulence, diarrhea and abdominal discomfort. For this reason, nutritive sugar substitutes are considered to be a less attractive alternative to table sugar than non-nutritive sweeteners.
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