Diabetes and Dietary Supplements
- Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high. Over time, having too much glucose in your blood can cause health problems.
- About 9.4 percent of the people in the United States have diabetes, but about one in four people who have diabetes don’t know it.
- Although diabetes has no cure, people with diabetes can take steps to manage their condition and stay healthy. Taking insulin or other diabetes medicines is often part of treating diabetes, along with healthy food choices and physical activity.
More About Diabetes
- The most common type of diabetes is type 2 diabetes, in which your body does not make or use insulin well. This type of diabetes occurs most often in middle-aged and older people, but it can develop at any age, even in childhood.
- You are more likely to develop type 2 diabetes if you are 45 years old or older, have a family history of diabetes, or are overweight. Physical inactivity, race, certain health problems such as high blood pressure, having prediabetes, or having had gestational diabetes while pregnant also affect your likelihood of developing type 2 diabetes.
- For more information about diabetes and related conditions, see the National Institute of Diabetes and Digestive and Kidney Diseases Web site.
What the Science Says About the Effectiveness and Safety of Dietary Supplements for Diabetes
- Alpha-lipoic acid is being studied for its effect on complications of diabetes, including diabetic macular edema (an eye condition that can cause vision loss) and diabetic neuropathy (nerve damage caused by diabetes).
- In a 2011 study of 235 people with type 2 diabetes, 2 years of supplementation with alpha-lipoic acid did not help to prevent macular edema.
- A 2016 assessment of treatments for symptoms of diabetic neuropathy that included 2 studies of oral alpha-lipoic acid, with a total of 205 participants, indicated that alpha-lipoic acid may be helpful.
- High doses of alpha-lipoic acid supplements can cause stomach problems.
- Found in many foods, chromium is an essential trace mineral. If you have too little chromium in your diet, your body can’t use glucose efficiently.
- Taking chromium supplements, along with conventional care, slightly improved blood sugar control in people with diabetes (primarily type 2) who had poor blood sugar control, a 2014 review concluded. The review included 25 studies with about 1,600 participants.
- Chromium supplements may cause stomach pain and bloating, and there have been a few reports of kidney damage, muscular problems, and skin reactions following large doses. The effects of taking chromium long-term haven’t been well investigated.
- We don’t have reliable evidence that any herbal supplements can help to control diabetes or its complications.
- There are no clear benefits of cinnamon for people with diabetes.
- Other herbal supplements studied for diabetes include bitter melon, various Chinese herbal medicines, fenugreek, ginseng, milk thistle, and sweet potato. Studies haven’t proven that any of these are effective, and some may have side effects.
- We have little conclusive information on the safety of herbal supplements for people with diabetes.
- Cassia cinnamon, the most common type of cinnamon sold in the United States and Canada, contains varying amounts of a chemical called coumarin, which might cause or worsen liver disease. In most cases, cassia cinnamon doesn’t have enough coumarin to make you sick. However, for some people, such as those with liver disease, taking a large amount of cassia cinnamon might worsen their condition.
- Using herbs such as St. John’s wort, prickly pear cactus, aloe, or ginseng with conventional diabetes drugs can cause unwanted side effects.
- Found in many foods, including in high amounts in bran cereal, certain seeds and nuts, and spinach, magnesium is essential to the body’s ability to process glucose.
- Magnesium deficiency may increase the risk of developing diabetes. A number of studies have looked at whether taking magnesium supplements helps people who have diabetes or who are at risk of developing it. However, the studies are generally small and their results aren’t conclusive.
- Large doses of magnesium in supplements can cause diarrhea and abdominal cramping. Very large doses—more than 5,000 mg per day—can be deadly.
- For more information on magnesium, see the Office of Dietary Supplements (ODS) Magnesium: Fact Sheet for Consumers.
- Taking omega-3 fatty acid supplements, such as fish oil, hasn’t been shown to help people who have diabetes control their blood sugar levels or reduce their risk of heart disease.
- Fish and other seafood, especially cold-water fatty fish such as salmon and tuna, contain omega-3 fatty acids. Studies on the effects of eating fish have had conflicting results, according to two 2012 research reviews with hundreds of thousands of participants, and a 2017 review. Some research from the United States and Europe found that people who ate more fish had a higher incidence of diabetes. Research from Asia and Australia found the opposite—eating more fish was associated with a lower risk of diabetes. There’s no strong evidence explaining these differences.
- Omega-3 supplements don’t usually have side effects. When side effects do occur, they typically consist of minor symptoms, such as bad breath, indigestion, or diarrhea.
- Omega-3 supplements may interact with drugs that affect blood clotting.
- For more information on omega-3 supplements, see NCCIH’s Omega-3 Fatty Acids Web page.
- An assessment of 4 studies involving more than 20,000 total participants found that selenium supplementation did not reduce the likelihood that people would develop type 2 diabetes.
- Long-term intake of too much selenium can have harmful effects, including hair and nail loss, gastrointestinal symptoms, and nervous system abnormalities.
- For more information on selenium, see the ODS Selenium Fact Sheet for Consumers.
- Studies generally show that taking vitamin C doesn’t improve blood sugar control or other conditions in people with diabetes. However, a 2017 research review of 22 studies with 937 participants found weak evidence that vitamin C helped with blood sugar in people with type 2 diabetes when they took it for longer than 30 days.
- Having low levels of vitamin D is associated with an increased risk of developing a metabolic disorder, such as type 2 diabetes, metabolic syndrome, or insulin resistance, studies and research reviews from the past 5 years have found. However, taking vitamin D doesn’t appear to help prevent diabetes or improve blood sugar levels for adults with normal levels, prediabetes, or type 2 diabetes, a 2014 research review of 35 studies with 43,407 participants showed.
- Taking too much vitamin D can cause nausea, constipation, weakness, kidney damage, disorientation, and problems with your heart rhythm. You’re unlikely to get too much vitamin D from food or the sun.
- For more information on vitamin D, see ODS’s Vitamin D: Fact Sheet for Consumers.
- The evidence is still very preliminary on how supplements or foods rich in polyphenols—antioxidants found in tea, coffee, wine, fruits, grains, and vegetables—might affect diabetes.
NCCIH is supporting research on the possible effects of:
- Components of grape skin on blood sugar control
- Chelation therapy on heart health in people who have diabetes and have had a heart attack
- Marijuana on the body’s metabolism and risk of developing type 2 diabetes
- Acupuncture on painful diabetic neuropathy (nerve damage) in underserved patients.
More To Consider
- The FDA is warning consumers not to buy illegally marketed, potentially dangerous products claiming to prevent, treat, or cure diabetes. These products make claims like “lowers your blood sugar naturally” or “inexpensive therapy to fight and eliminate type II diabetes.” They may contain harmful ingredients and the label may not tell you what you’re actually taking.
- Fraudulent diabetes products can be especially dangerous if you use them instead of proven treatments for diabetes. Without proper disease management, people with diabetes are at greater risk of developing serious complications.
- Keep in mind that dietary supplements may interact with medications or other dietary supplements. To learn more, visit NCCIH’s Web page on Dietary and Herbal Supplements.
- Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.
For More Information
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NCCIH thanks D. Craig Hopp, Ph.D., and David Shurtleff, Ph.D., NCCIH, for their contributions to the 2018 update of this publication.
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