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Purslane as a source of omega-3: a reality check

by Monica Reinagel, MS, LDN

Purslane has gained a reputation as being a good source of omega-3 fatty acids. An oft-cited 1992 analysis, published in the Journal of the American College of Nutrition, found that 100 grams of purslane contained 300-400 mg of omega-3 fats.

But if you search the scientific literature, you’ll see that the amount of omega-3 fats in purslane varies a LOT, depending on the variety, the age of the plant, the part of the plant you analyze (leaves, stems, seeds), and the time of harvest. The purslane analyzed in the 1992 study was clearly at the high end of the range.

Is purslane a valuable source of omega-3 or not?

It’s true that, compared to other green vegetables, purslane is rich in omega-3 fatty acids. About half the fat in purslane is omega-3. But green vegetables are very low in fat, so that doesn’t add up to much.

Let me put this in perspective for you: Even if you were lucky enough to got some high octane purslane like the stuff analyzed by Simopoulos in 1992, you’d need to eat 4 pounds of it to get the amount of ALA found in one tablespoon of flaxseed oil.  Hope you’re hungry!

Probiotic Confusion

by Monica Reinagel, MS, LDN

Probiotics Last week, I answered a question from a reader who had seen a study showing that probiotic supplements reduced cold and flu symptoms in children. He reasoned that eating yogurt every day might be a good step and wondered how much he’d have to eat to get a similar “dose” of probiotics.   To answer his question, I compared the number of active cultures in a typical probiotic supplement to the number of active cultures in a typical yogurt.

But I missed an opportunity to clarify what I think is a widespread misunderstanding about probiotics. Many people think of all probiotic supplements and foods as being somewhat interchangeable. They’re not.

Probiotics: an umbrella term for thousands of different bacteria

In terms of labeling foods and supplements, the FAO/WHO defines probiotics as “Live microorganisms which when administered in adequate amounts confer a health benefit on the host.”  That’s any health benefit.

There are hundreds of different strains of lactobacillus bacteria and they offer a variety of potential health benefits to humans. Some colonize the large intestine, others live in the lining of the stomach, still others have an affinity for the mucus membranes in the nose.  Of the many strains likely to colonize the large intestine, for example, some may improve gut immune function, others digest complex sugars, others may benefit the host by producing vitamin K.

There are also lactobacillus bacteria that don’t do much of anything to improve or defend your health. These, while harmless, would technically not be classified as probiotics–although they might still be considered “live and active cultures.”

Foods versus supplements

Most probiotic foods contain a variety of bacterial strains–your average supermarket yogurt might contain six different bacterial strains. And the lactobacillus bacteria found in yogurt are not necessarily the same as those found in other fermented foods like kefir or kim-chi.

See also: A World Tour of Lactobacillus Bacteria

Many of the studies you read about use “boutique” strains that are not likely to be found in any traditionally-fermented foods. In the case of the study I mentioned above, for example, they used two trademarked strains called Lactobacillus acidophilus NCFM and Bifidobacterium lactis Bi-07.

Is there any point to consuming probiotic foods?

I still think there are general health benefits to eating traditionally-fermented foods like yogurt, kefir, kim-chi, kombucha, sauerkraut, and miso. Eating a variety of fermented foods, which provides a wider variety of bacterial strains, might offer a wider range of benefits.

But we need to be careful about assuming that the findings on a particular strain apply to all probiotics and probiotic foods.  If you’re going for a specific therapeutic benefit, such as protecting against side effects while taking antibiotics or improving flu resistance, there’s no guarantee that yogurt or any other fermented food will contain the same bacteria as were used in a particular study.

Similarly, when shopping for probiotic supplements, pay attention to the individual strains in that supplement and how they compare with the strains used in various studies you might be responding to.



What’s so magical about the Mediterranean Diet?

by Monica Reinagel, MS, LDN

Forget the mouse studies. After a couple weeks of controversial and much-contested rat studies on the effects of carbohydrates on various aspects of metabolism and disease, here’s a study involving 200 newly-diagnosed, diabetic humans.  Half were told to follow a Mediterranean-style diet, rich in vegetables, whole grains, and monounsaturated fats from poultry, fish, and olive oil and limiting carbohydrates to 50% or less of total calories.

The other half were assigned to a “low-fat” diet, which also emphasized whole grains and discouraged sweets and high fat snacks. Fat was limited to 30% or less of calories and saturated fat to 10% or less of calories.

After four years, the Mediterranean group had lost more weight and was only half as likely to need anti-diabetic medications.

What’s the real difference here?

Notice that the macronutrient distributions between the two diets are not all that different. The Mediterranean diet was not terribly low in carbohydrates (although it’s being described in media reports as a “low-carb” diet). The low-fat diet isn’t really all that low in fat. The two percentages certainly aren’t mutually exclusive. In fact, it’s entirely possible that the distribution of fats, proteins, and carbohydrates between the two groups was very similar.  Nor can we necessarily chalk it up to refined versus complex carbohydrates.  Both groups were instructed to favor whole grains.

Perhaps it was just a matter of what the dieters were told to focus on.  The Mediterranean group was told what to eat: vegetables, fish, grains, olive oil. The low-fat group were told what to avoid: sugary snacks and high-fat foods.  Could it be as simple as casting dietary recommendations in terms of positives instead of negatives?

Can yogurt protect you from the flu?

by Monica Reinagel, MS, LDN

Can Yogurt Reduce Risk of FluQ. I recently read about a study showing that probiotics protected kids from getting the flu. It seemed like a pretty powerful study in favor of the health benefits of yogurt, at least in kids. Do you have any recommendations for a reasonable “dose” of yogurt would be for an adult?

A. Yes, I noted that study with interest as well. The kids (about 300 of them, aged 3 to 5) were taking probiotic supplements or placebo pills twice a day. The kids getting the probiotics had about half as many fevers, coughs, and runny noses, took fewer prescriptions and missed fewer days of school.

We should note that the study was funded by a company that makes probiotic products.  That said, the results were published in a peer-reviewed journal (Pediatrics) so the study design apparently passed muster.

See also: Can we Trust Industry Funded Research?

There’s no RDA for probiotics for kids or adults so it’s hard to say what a good”dose” might be. Most probiotic supplements contain 10 to 20 billion active cultures per dose at the time of manufacture. Yogurt that carries  the “Live and Active Cultures” seal is certified to contain at least 100 million cultures per gram at the time of manufacture, which translates into about 22 billion live cultures in an eight ounce cup of yogurt.

So, I’m thinking that a single serving of yogurt every day would be a reasonable start for kids and adults. But the amount of sugar (often high fructose corn syrup) in sweetened yogurts is shocking. I’d advise you to steer clear of sweetened (and artificially-sweetened) yogurts and go for the plain yogurt. Sweeten (if you must) with fruit or a drizzle of honey.

Can yogurt protect you (or your kids) from getting the flu this season? Might help and can’t hurt (unless you’re lactose intolerant).




New Guidelines for Added Sugars

by Monica Reinagel, MS, LDN

The American Heart Association has come out with new challenge: Limit added sugars to no more than 25g (about 6 tsp) per day for women and 36g a day for men.  Right now, we consume on average around three and a half times that much.

Where did they come up with the numbers?

The AHA reasons that “excessive consumption of added sugars is contributing to over-consumption of discretionary calories,” which, in turn, leads to obesity and increases heart disease risk.  Discretionary calories are the ones we eat just for the fun of it and not necessarily to meet our nutritional needs. The USDA dietary guidelines recommend that these discretionary calories should be limited to 10% of total calories. The AHA figures that added sugars should make up no more than half of the discretionary calorie allowance.

This new recommendation sets the bar on added sugars even lower than the “10% of calories” limit that was suggested a few years back by the World Health Organization.

True confessions

I have to be perfectly honest with you: I’d have to make some changes in my diet in order to limbo under the new 25g bar. I don’t drink soda, which is the primary source of added sugars for most Americans.  And I don’t eat a whole lot of processed foods.  But I do enjoy ice cream. I often bake muffins or make granola for breakfast. I have a square of chocolate after dinner most nights. It adds up quickly.

What counts as an added sugar?

Of course, it depends on what you count.  Most sources agree that naturally occurring sugars in fruit and dairy don’t count as added sugars.  I agree.

Many try to argue that “natural” sugars like honey or molasses also shouldn’t count, but I don’t see why.  Honey, molasses, maple syrup, agave syrup, refined white sugar, brown sugar, and organic cane sugar are all concentrated sources of sugar. Some are more refined than others, but the nutritional and metabolic impacts are similar.  In other words, I’m not off the hook simply because I make my granola with honey. It’s still a source of added sugar in my diet. Here’s my recipe for granola by the way.  Each serving contains 9g of added sugar.

Adding it up

It’s fairly easy to keep track of the sugars that we add ourselves, whether at the table or in the mixing bowl. The real trick is keeping track of the sugars in processed foods. Check the ingredient lists for sugar and all its aliases (such as corn sweetener, corn syrup, dextrose, glucose, high fructose corn syrup, honey, maltose, malt syrup, molasses, sucrose, and syrup). The higher up these are in the list, and/or the more of them you see listed, the more sugar the food contains.

The nutrition facts label has a line for “total sugars” and you can use this to keep a tally, but keep in mind that this number includes the natural sugars in fruit and dairy as well as added sugar (honey, etc.).

For example, a container of fruited low-fat yogurt contains 47grams (!) of sugars. However, a container of plain low-fat yogurt contains 17g of naturally-occurring sugar.  That means that the fruited yogurt has 30g of “added” sugars.  Oops…you’re already over the limit.

It’d be a bit trickier to sort out the natural versus added sugars in something like a store-bought oatmeal raisin cookie. But you get the idea.

So, how hard would it be for you to limit yourself to 25 grams of added sugar a day? How hard would it be if you also avoided artificial sweeteners?

Are Saturated Fats from Vegetables Better?

by Monica Reinagel, MS, LDN

I’ve been getting a lot of questions about coconut oil–a vegetable source of saturated fat. It’s alleged health benefits are being heavily promoted but there’s not much solid evidence to back up the claims.

It’s hard to say whether saturated fats from vegetables are better than saturated fats from animals–in part because the evidence that saturated fats cause heart disease looks increasingly shaky. Maybe the truth is that the vegetable saturated fats aren’t better than animal saturated fats but that the animal fats weren’t that bad in the first place?

How can people who try so hard to get it right get it wrong so often?

Why is it so hard for us to get it right? As Marion Nestle’s argues in the introduction to her recent book, What to Eat, part of the problem is embedded in the very nature of scientific research. In an effort to reduce the variables, nutritional research focuses too much on the details and not enough on the big picture.

“The range of healthful nutrient intake is broad, and foods from the earth, tree, or animal can be combined in a seemingly infinite number of ways to create diets that meet health goals,” she writes. “The attention paid to single nutrients, to individual foods, and to particular diseases distracts from the basic principles of diet and health…But you are better off paying attention to your overall dietary pattern than worrying about whether any one single food is better for you than another.”

I suspect that the kind of reductionist thinking that Nestle is deploring is exactly what got us into this mess about saturated fat.  We were looking for a culprit for heart disease. We found one in saturated fat…but I suspect we overlooked the critical importance of the context in which that saturated fat was being consumed.

Replacing High Fructose Corn Syrup with Sugar: Big Deal.

by Monica Reinagel, MS, LDN

It no longer matters whether it’s actually true that high fructose corn syrup (HFCS) is toxic to our livers, full of mercury, or to blame for exploding obesity rates.

The tales that have been told about HFCS have become so pervasive that it’s beginning to hurt sales.  Say no more! Manufacturers are now switching back to cane sugar–and using it as a marketing ploy.  “Sweetened with real cane sugar!” the packages proclaim.

Sugar is now a healthy ingredient. How Orwellian.

So, what have consumers gained? Well, many feel that products sweetened with sugar taste better. But are they healthier? In my opinion, no.

If we continue to over-consume highly sweetened foods and beverages, we will likely continue to see massive rates of obesity, diabetes, and heart disease.  Switching to foods and beverages sweetened with cane sugar rather than high fructose corn syrup is unlikely to have any measurable impact on public health–except perhaps indirectly.

Switching back to sugar will drive the price of these foods and beverages up. Maybe cost pressures will help shrink the ridiculously over-sized package and serving sizes. The only way anyone benefits from eating cane sugar instead of HFCS is by eating less of it.

See also “Scientists see little benefit in scramble to swap processed sweeteners for natural ones” in today’s Chicago Tribune.

Looking For the Truth on Fructose? Keep Looking.

by Monica Reinagel, MS, LDN

I really don’t get it. Fructose is the dietary scapegoat of the decade, blamed for everything from obesity to liver disease. Never mind that most high fructose corn syrup is in actuality no higher in fructose than regular table sugar. Never mind that the increase in fructose consumption (the so-called smoking gun) over the last ten years was accompanied by an equivalent increase in glucose consumption. Never mind that pure fructose is not found in nature or in the normal human diet–it is virtually always consumed in combination with other sugars.

There is so much myth and hysteria circulating about fructose, you would think some solid scientific inquiry would help clarify the situation. But how are we ever going to figure out what part (if any) fructose per se plays in our health problems when researchers continue to design studies that fail to isolate the variables?

For example, this latest study, published in the American Journal of Clinical Nutrition compared a diet that was high in fructose and and also provided a third too many calories with a diet that contained less fructose and the proper number of calories. Those on the “high fructose” diet experienced several unfavorable changes in their blood lipid profiles.

So what? How many of those effects were due to simply overeating? Why not compare two diets with the same number of calories but differing amounts of fructose? And please don’t show me studies that compare diets containing only fructose versus diets containing only glucose because these type of diets don’t occur outside a laboratory.

Is too much sugar to blame for many of our health woes? You bet. Is fructose metabolized differently than glucose and other sugars? For sure.  Is fructose poison to our bodies? Fructose is like any other sugar molecule: when refined, concentrated, and consumed in excess quantities, it’s not good for you.

Want to improve your health? Cut down on added sugars–that includes table sugar, HFCS, maple syrup, honey, agave nectar, fruit juice concentrates, and foods made with any of these. You’ll be cutting down on fructose in the process–if that makes you feel better.

But I’ve yet to be convinced that fructose is harmful except in cases where sugar (in general) makes up too large a proportion of calories. In these cases, the effects of fructose on the liver and blood lipids are simply one of the mechanisms by which too much sugar damages human health–no more or less dangerous than any number of other mechanisms, such as the effect of glucose on blood sugar and insulin levels, or the effect of excessive calorie intake on body fat and weight.