Landmark findings hold hope for fish-focused strategy to prevent insulin-dependent (type I) diabetes in kids
by Craig Weatherby
Diabetes comes in two forms. The most common by far—called “type II” or “adult-onset”—usually occurs in middle age, and is caused primarily by poor diets, lack of exercise, and being overweight.
(The average age of onset for type II diabetes keeps dropping as children eat more junk food and get less exercise.)
- Higher omega-3 intake appeared to cut type I diabetes risk 37 to 77 percent among susceptible kids.
- Results were based primarily on diet surveys, and largely supported by blood tests.
- Researchers see a strong link between the steady rise in type I diabetes rates and the coincident drop in American’s omega-3 intake.
Type I is far less common. It strikes people in early childhood, is closely related to genetic factors, requires daily insulin shots, and until now, has resisted all attempts at prevention.
While many people with type I diabetes live full, long lives, they need to restrict their diets, monitor their blood sugar levels constantly, and inject insulin daily.
And, like advanced cases of type II diabetes, type I comes with the risk of various crippling and life-threatening complications.
Given its current incurability, the holy grail of type I diabetes research is a reliable preventive therapy.
So the release last week of a report that omega-3s may help prevent type I diabetes in many genetically susceptible kids made headlines worldwide.
Omega-3s drop childhood diabetes risk dramatically
Type I diabetes results when the body develops islet-cell autoimmunity (IA)—a destructive immune response to these insulin-producing factories in the pancreas.
Kids are more likely to develop type I diabetes when they have either or both of two major risk factors—a genetic marker known as the “HLA genotype”, and a sibling or parent with type I diabetes.
Researchers at the University of Colorado and the University of Florida collaborated to see whether children’s intake of omega-3 and omega-6 fatty acids influenced their risk of developing IA.
They recruited 1,770 children with type I diabetes risk factors for a study called the Diabetes Autoimmunity Study in the Young (DAISY), which was conducted in Denver, Colorado (Norris JM et al 2007).
The researchers followed the children for five years—from age one to age six—using diet surveys to record the children’s intake of omega-3 and omega-6 fatty acids.
Getting kids to eat omega-3s
Omega-3s are found in fish and in green leafy foods. Both are useful sources of omega-3s.
However, only five to 15 percent of the short-chain omega-3s in plant foods get converted to the long-chain omega-3s found only in fish, which are absorbed much more efficiently, and are the kind the body needs for cell membranes, and to produce the anti-inflammatory chemicals that the DAISY researchers believe were responsible for the reduction in diabetes risk seen in their new study.
Children’s tastes are established very early in life, so it makes sense to start feeding them mild-flavored greens and fish as soon as possible. In addition to canned greens for babies, you can puree boneless fish and well-washed greens or lettuces. Kids can eat greens and soft, boneless fish as soon as they are ready for solid foods.
Of course, children and pregnant mothers should avoid high-mercury species (shark, tilefish, swordfish, King mackerel).
But the rewards of most fish— especially wild Alaskan species— far outweigh any risks. For more on this, see “Findings Verify Safety and Value of Higher Maternal Fish Intake”.
At the end of the five-year study, 58 of the 1,770 children had developed IA (hence, type I diabetes).
After the researchers adjusted for relevant risk factors – genetic makeup, family history of type 1 diabetes, caloric intake, and omega-6 fatty acid intake – they reported that the more omega-3s a child consumed, the less likely he or she was to have developed IA, which leads invariably to type I diabetes.
And the effect was dramatic… the kids with the highest reported omega-3 intake were 55 percent less likely to develop IA (hence, type I diabetes).
The protective effect of omega-3s appeared even stronger—an amazing 77 percent reduction in risk—in children who tested positive for two or more “auto-antibodies” associated with IA.
The authors expressed their conclusion in unequivocal terms: “Dietary intake of omega-3 fatty acids is associated with reduced risk of IA in children at increased genetic risk for type 1 diabetes” (Norris JM et al 2007).
Tissue tests confirm the omega-3 effect
Diet surveys can’t provide precise information on a child’s fish or omega-3 intake.
So, because the study’s results were potentially momentous, the scientists sought to confirm the diet-survey-based findings by also analyzing the fatty acid composition of blood drawn from a subgroup of 244 children.
They then compared the risk of developing IA—the proximate cause of type I diabetes—to the fatty acid content of the children’s red blood cell membranes.
In this smaller “case-cohort” part of the DAISY study, the kids with the highest levels of omega-3s in their red blood cell membranes were 37 percent less likely to develop IA.
The reasons for the still substantial, but less powerful, protection seen in this group were not immediately explicable.
However, the results of this subsection of the study support its general findings, and underscore the wisdom of using tissue tests to confirm diet-disease associations based on diet surveys.
Researchers note strong diet-diabetes link
The past few decades have witnessed a dramatic jump in the incidence of type I diabetes in the United States and Europe alike.
This upward spike parallels steep declines in American’s intake of omega-3s, and sharp increases in their consumption of omega-6 fatty acids.
Both trends result from increased consumption of foods rich in omega-6s: primarily, grain-fed meats and poultry, and foods cooked in or containing the cheapest and most common vegetables oils (corn safflower, sunflower, soy, cottonseed).
Mothers’ vitamin D may protect, too
In an earlier, separate part of the DAISY study, published four years ago, the researchers examined the effects of mothers’ fatty acid and vitamin D intake on their children’s risk of developing type I diabetes.
They recruited 233 mothers with type I diabetes or risk factors for it, and asked them to recall their intake of food and nutritional supplements during the third trimester of pregnancy. The researchers them followed their offspring for four years, to see if they developed islet auto-immunity (IA), which leads to type I diabetes.
In the end, the children of women who reported the highest levels of vitamin D intake from foods had significantly less risk of developing IA.
Interestingly, higher intake of vitamin D via supplements showed no protective effect, nor did higher intake of omega-3 fatty acids. (In light of the positive outcome of the new study reported here today, the negative result vis a vis maternal omega-3 intake will be tested again in a new, more rigorous, NIH-funded trial.)
As the researchers wrote, “Our findings suggest that maternal intake of vitamin D through food during pregnancy may have a protective effect on the appearance of IA in offspring” (Fronczak CM et al 2003).
Dr. Michael Clare-Salzler, a co-author of the new study, made these cogent comments in a press release:
“The foods we are eating now are qualitatively much different than those produced on a 1900s-era farm. When animals are commercially raised today, they are often fed grains rich in omega-6 fatty acids, fatty acids that can promote inflammation. In the old days, animals received a much more balanced intake of omega-3 and omega 6-fatty acids.” (Ross MF 2007)
He noted that, compared with how people ate in 1907, the amount of omega-3s in modern American diets is about 30 times lower.
Why would this shift in fatty acid intake raise the risk of an auto-immune disease like type I diabetes?
In and auto-immune disease like type I diabetes, the body’s immune system mounts an inflammatory attack on affected tissues—including a spray of cell-damaging free radicals—as though the tissues consisted of infectious microbes or cancer cells.
This inflammatory assault is mediated by ephemeral, hormone-like chemicals called prostaglandins, which are made from omega-3 and omega-6 fatty acids.
The omega-6s overabundant in modern diets—and in their consumers’ cell membranes—are used to make pro-inflammatory prostaglandins.
In contrast, the body uses omega-3 fatty acids to make anti-inflammatory prostaglandins.
This distinction illuminates the results of the new study, as Dr. Clare-Salzler explained:
- “Animal studies have shown inflammation in the insulin-producing cells of the pancreas is an early event that leads to type 1 diabetes.”
- “From these studies in mice, it appears if you thwart inflammation you can prevent the disease from occurring. The human parallel in this study indicates that higher dietary intake of anti-inflammatory omega-3 fatty acids reduces the risk of developing an immune response to the insulin-producing cells” (Ross MF 2007).
The DAISY researchers will be conducting new studies, funded by the National Institutes of Health, designed to determine two things:
- Whether babies who receive omega-3s—specifically, DHA from fish oil—show fewer signs of inflammation.
- Whether DHA protects infants and children from the development of auto-antibodies (immune system proteins) that lead to diabetes.
As the authors wrote, if the outcomes of the planned studies are positive, “…dietary supplementation with omega-3 fatty acids could become a mainstay for early intervention to safely prevent the development of type 1 diabetes.”
The new results are extremely encouraging, as affirmed by Professor Charles Serhan, M.D., a researcher at Harvard Medical School:
“…you may now be able to add back through the diet these essential omega-3 fatty acids, and then they will be utilized by the body to generate its own set of protective molecules [anti-inflammatory prostaglandins] that help to instruct the immune cells in the local environment not to attack the insulin-producing islets cells in the pancreas... these are very powerful and potentially very important results” (Ross MF 2007).
We’ll keep you posted!
- Norris JM, Yin X, Lamb MM, Barriga K, Seifert J, Hoffman M, Orton HD, Baron AE, Clare-Salzler M, Chase HP, Szabo NJ, Erlich H, Eisenbarth GS, Rewers M. Omega-3 polyunsaturated fatty acid intake and islet autoimmunity in children at increased risk for type 1 diabetes. JAMA. 2007 Sep 26;298(12):1420-8.
- Ross MF. Diet rich in fatty acids could thwart diabetes onset. University of Florida Health Science Center. Accessed online September 30, 2007 at http://www.health.ufl.edu/continued_news_story.shtml
- Fronczak CM, Baron AE, Chase HP, Ross C, Brady HL, Hoffman M, Eisenbarth GS, Rewers M, Norris JM. In utero dietary exposures and risk of islet autoimmunity in children. Diabetes Care. 2003 Dec;26(12):3237-42.