Berry news fuels a raging debate over diabetes cures and foes; The Healthy Skeptic weighs in
Do you have diabetes?
One-third of diabetics don't know they have the disease, and you may be among them.
The good news is that it's very preventable with the seven lifestyle strategies listed below.
But there's a big debate over whether — once you get diabetes — a very-low-carb diet can replace drugs and even reverse the disease.
We're talking about Type II diabetes, which has roots in our genes and lifestyles — not Type I diabetes, which is usually caused by an autoimmune response and is apparent soon after birth.
Type II diabetes is sometimes called “adult-onset diabetes”, but rising numbers of young people and children have or show signs of diabetes.
We'd like to relate good news about berries' potential to help prevent diabetes, and cover two sides of a debate over the benefits of very-low-carb diets to people with diabetes.
First, let's recall the diabetes basics, which help explain the benefits of berries.
What is Type II diabetes?
Diabetes is characterized by routinely high blood sugar levels — also called hyperglycemia.
Almost one in 10 Americans (30 million) are diagnosed with diabetes, and another 86 million have so-called prediabetes.
Excess blood sugar (glucose) results from “insulin resistance”, which means the body's cells don't absorb enough blood sugar in response to release of the hormone insulin.
At first, the body simply makes more of the hormone. But insulin resistance usually worsens, until the body can't make enough extra insulin to compensate for its loss of effectiveness.
Excess weight is a key risk factor, so it's alarming that one in three adults qualify as obese, while two thirds rank as overweight.
Be aware of these common symptoms:
• Blurred vision
• Frequent thirst
• Extreme fatigue
• Frequent urination
• Slower healing of bruises and cuts
• Frequent hunger, even after eating
• Tingling, numbness or pain in the hands and feet
Excess weight: Not the only cause
It's a myth that only overweight people get diabetes.
Lean people can get diabetes, which has causes aside from excess weight.
These non-weight causes include genetic vulnerability, chronic inflammation and/or stress, fatty liver disease, autoimmune conditions, and various combinations of these.
Even lean, generally healthy children of diabetics run a much higher risk for insulin resistance, compared with the children of non-diabetics.
The defect behind this inherited vulnerability impairs the ability of body cells to burn blood sugar or fats, leading fat to clog muscle and organ cells — a condition called lipotoxicity.
Berry good news for reducing diabetes risk
As the American Diabetes Association says, diets dominated by whole, unrefined foods help discourage diabetes.
Conversely, the risk is raised by diets high in processed, packaged, and prepared foods, and refined carbohydrates such as white flour baked goods and white rice.
Supporting the benefit of whole foods, a recent evidence review suggests that berries can help cut diabetes risk quite significantly.
Berries are rich in colorful, polyphenol-type antioxidants called anthocyanins — the same plant chemicals that color autumn leaves so brightly.
Along with berry fibers, the polyphenols in berries likely account for most of their apparent ability to reduce diabetes risk.
In a recent evidence review, researchers from China's Zhejiang University examined eight studies that compared people's intake of either berries or berry-source anthocyanins to their chances of developing diabetes (Guo X et al. 2016).
The Chinese team's analysis linked higher anthocyanin intakes to a 15% lower risk for diabetes, and higher berry consumption to an 18% drop in risk.
Specifically, the risk of diabetes declined by 5% with every 7.5 mg of anthocyanins or 17 grams (just over one-half ounce) of fresh berries consumed daily.
The evidence review's authors attributed these estimated risk reductions to three documented properties of dietary anthocyanins:
• Antioxidant effects (indirect).
• Stabilize blood sugar (glucose) levels.
• Dampen inflammation, which promotes and aggravates diabetes.
We should note that polyphenols and other food-borne “antioxidants” don't exert direct antioxidant effects in the body.
Instead, they prompt our genes to ramp up the body's own antioxidant network, while curbing damaging inflammation and excessive production of free radicals.
Many scientists now study the indirect, “nutrigenomic” influences — almost entirely beneficial — exerted on human genes by the antioxidants that abound in whole plant foods (and in wild salmon, via their diet of tiny, pinkish shrimp and zooplankton).
Earlier research points to fruits and veggies
Another recent analysis — which encompassed 23 research papers — produce similar findings.
Its authors looked for links between intake of fruits, vegetables, and their fiber, and the risk of Type II diabetes (Wang PY et al. 2015).
The results linked higher intakes of fruits — especially berries — with reduced risk for diabetes.
Strong links were also seen between reduced diabetes risk and higher intakes intake of colorful vegetables, including cruciferous types like broccoli and kale.
Fruit and vegetables are rich sources of fiber, antioxidants, folate, and potassium, the combination of which could explain their protective effects.
And diets high in fruits and vegetables will tend to be lower in foods that promote diabetes, such as white flour goods — and cheap, omega-6-laden, inflammation-promoting vegetable oils (such as corn, soy, safflower, sunflower, and cottonseed)
Dietary fiber appears to improve insulin sensitivity, slow absorption of carbohydrates, and support insulin production.
In addition, the antioxidants in fruits and vegetables tend to reduce oxidative stress, which interferes with our cells' ability to absorb blood sugar.
There's also evidence that food-borne antioxidants improve insulin sensitivity and thereby reduce the risk or severity of diabetes.
Omega-3s versus diabetes
As we've reported in the past, omega-3s exert effects similar to those of a major class of diabetes drugs.
These drugs, called glitizars, act on cellular switches called PPARs in ways that raise levels of HDL (“good”) cholesterol, lower blood fat (triglyceride) levels, and improve insulin sensitivity.
(See Drug May Help Prevent Diabetes: Omega-3s Exert Comparable Effects.)
Judging by the results of a recent Australian clinical trial, omega-3s also appear to improve insulin sensitivity — but only in women, not in men (Abbott KA et al. 2016).
That's big news, because it's long been thought that omega-3s didn't improve insulin sensitivity, making it unlikely that fish oil could reduce the risks of nerve, kidney, or eye damage associated with chronically high blood sugar levels:
However, the results of the new Australian trial are highly encouraging, at least for women.
And, as researchers from the Mayo Clinic wrote earlier this year, the positive results of animal studies also suggest that more clinical research is needed before dismissing omega-3s as aids to insulin sensitivity:
“Observational studies in humans are encouraging, however, the vast majority of human intervention [clinical] studies fail to demonstrate the benefit of omega-3s in type 2 diabetes or insulin-resistant non-diabetic people. Nevertheless, there are still several unanswered questions regarding the potential impact of omega-3s on metabolic function in humans.” (Lalia AZ et al. 2016)
That issue aside, omega-3s clearly alleviate three cardiovascular risks linked with diabetes: High triglyceride levels, low HDL levels, and increased inflammation.
And omega-3s reduce the risk of key dangers tied to those diabetes symptoms: stroke, second heart attacks, and sudden cardiac death.
Seven tips for discouraging diabetes
These seven tips stand on evidence that's pretty solid:
- Get off the couch. Diabetes risk rises by 20 percent for every two hours spent watching TV.
- Keep weight in check. Avoiding excess pounds ranks among the strongest preventive steps.
- Focus on whole plant foods. Diets high in vegetables and whole grains keep blood sugar and appetite in check. Choose a good variety, prepared in various ways.
- Choose whole-food sources of carbs. Whole grains and beans protect against diabetes, while white rice, white bread, white pasta, and pastries raise risk for the disease.
- Dump sugary drinks — including fruit juices — and choose water, coffee, or tea instead.
- Favor helpful fats. Choose oils high in monounsaturated fats, such as olive (antioxidant-rich extra virgin grade), macadamia nut, high-oleic sunflower or safflower, and canola. And it's clearly safe to use coconut oil (whose saturated and MCT fats are actively healthful), and limited amounts of butter, lard. Avoid cheap oils high in omega-6 fats, such as corn, soy, regular sunflower or safflower, and cottonseed.
- Limit red meat, avoid processed meat, and favor grass-fed beef over standard grain-fed, because of its healthier fat profile. Population studies suggest that you may cut your diabetes risk substantially by getting most of your protein and fat from fish, shellfish, poultry, whole, and nuts.
Two top clinicians promote low-carb diets over drugs
Recently, The New York Times presented both sides of a diabetes debate.
The debate is about a key question: can low-carb diets effectively treat diabetes?
Let's start with the case made by two doctors expert in weight loss and diabetes, who claim that low-carb diets can reduce or eliminate the need for insulin and other drugs.
Sarah Hallberg, D.O., is a weight-loss/diabetes clinician at Indiana University Health's Arnett Hospital.
Dr. Halberg co-authored a recent opinion essay in The New York Times with Osama Hamdy, M.D., medical director of weight loss at the Harvard Medical School's Joslin Diabetes Center.
In their September 10, 2016 essay, Drs. Halberg and Hamdy decried what they deem an excessive, potentially harmful focus on drugs versus diet for treating diabetes.
As they wrote, “A patient with diabetes can be on four or five different medications to control blood glucose [sugar], with an annual price tag of thousands of dollars.”
Hallberg and Hamdy expressed dismay that the American Diabetes Association and 45 other organizations now endorse costly, risky weight-loss bariatric surgery — which commonly causes adverse side effects – as a standard treatment option for diabetes.
They point to evidence — from preliminary clinical trials and their own experience with patients — suggesting that very-low-carb diets can treat Type II (adult-onset) diabetes.
The essay's authors cited two small clinical trials which found that many more low-carb dieters were able to stop taking one or more diabetes drugs, compared with participants who followed a moderate-carb, lower-fat, calorie-restricted diet.
These and other, larger, trials also found that low-carb diets improved hemoglobin A1C levels — the primary medical measure of diabetes — significantly more than low-calorie diets that did not restrict carbohydrates as much.
Drs. Hallberg and Hamdy acknowledged that the benefits of a low-carb diet depend on persistence, which can be difficult, given our innate genetic impulse to consume carbs.
Low-carbohydrate diets were standard diabetes treatment until synthetic insulin became available, which is when doctors began advising patients on insulin to consume carbs to prevent dangerously low blood sugar.
Sadly, in the late 1970s, medical authorities began recommending a high-carb, low-fat diet, in the mistaken belief that saturated fat causes cardiovascular disease.
That misguided advice probably fueled the diabetes epidemic, and it's persisted, even though — as Drs. Halberg and Hamdy point out — clinical trials consistently find low-carb diets more effective than low-fat diets at controlling blood sugar and curbing most cardiovascular risk factors.
Nonetheless, the current guidelines of the American Diabetes Association — issued in 2013 — say there's “no conclusive evidence of an ideal amount of carbohydrate intake for people with diabetes”.
Fortunately, the ADA guidelines stress that most carbs should come from whole foods, versus refined grains, baked goods, and packaged or prepared foods with added fats, sugar, or salt.
Times' medical reporter critiques low-carb claims
The New York Times' chief medical correspondent soon responded to the opinion essay by Drs. Hallberg and Hamdy.
Journalist Gina Kolata cited some evidence in favor of their opinion, including a small, short-term clinical trial in non-diabetic, overweight men, which found that insulin secretion dropped by half on a very-low-carb diet.
This outcome meant that the men required much less insulin to maintain normal blood glucose levels.
She quoted its lead author, Kevin Hall, M.D., of the National Institutes of Health: “Since diabetes results when the body can't produce enough insulin, perhaps it is a good idea to reduce the amount of insulin it needs by eating very-low-carbohydrate diets.”
However, as Ms. Kolata wrote, “Some longer-term studies, though, failed to show that low-carbohydrate diets benefited glucose control.”
One very big barrier to success is people's ability to stick to a low-carb diet over the long term.
Yoni Freedhoff of the University of Ottawa led a recent analysis of weight loss diets, and as he and his colleagues wrote: “Diet adherence is so challenging that it is poor even in short-term studies where all food is provided.”
The key is to find a diet that produces weight loss, and is relatively easy to maintain over time.
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