The Case For and Against Fruits: Are Fruits Healthy? Are They Good for a Diet? Is There A Best Time To Eat Them?

Fruits have been around a really long time. Most anthropologists and evolutionary biologists believe that the diet of early man consisted mainly of fruit, until such time when we diversified our food consumption by becoming hunter-gatherers and then eventually farmers. Even as access to fruits sometimes became limited due to climate change, it never completely disappeared from the human diet. But some people now argue that it should.

The anti-fruit crowd highlight four major arguments against fruits available today.

Argument 1: Fruits are contaminated and nutritionally depleted.

First, they claim that fruits have been so genetically modified and tainted by man-made chemicals that they no longer contain sufficient nutrients to meet human needs for such nutrients or that you should only eat them if they are organic. These arguments are usually put forth by pill-pushers who want you take to a pill instead of, or in addition to eating fruits.  To the former point, I say that my own extensive review of the scientific literature supports that fruits have been altered, but that they still contain more than sufficient nutrients to meet our daily needs, particularly if you eat even a few servings per day.

As to the organic issue, it's really a question of money. No rational person can argue that there is something good to be gained from eating something that has been exposed to pesticides, herbicides, fungicides, and other man made chemicals, and/or has been genetically modified.  Although the specific harms from these chemicals is still hotly debated, if you can afford to avoid them, you should surely do so, especially the Environmental Working Group's "Dirty Dozen." (See http://www.ewg.org/foodnews/)  If not, then rinse very carefully. I tend to rinse my blueberries at least three times under pressure before having them for breakfast.


Argument 2: Fruits are high in a sugar called fructose and that is not good for your liver, lipid levels, and diabetes

The next reason often given for avoiding fruits is their high fructose content. First of all, not all fruits have the same amount of fructose (For a more detailed description of how the body processes fructose, please read the American Journal of Clinical Nutrition primer found at

http://ajcn.nutrition.org/content/86/4/895.full)

To summarize the primer, the pancreas doesn't react to fructose until is is metabolized like it does to sucrose and glucose. Moreover, we don't need any dietary fructose to function.  However, even though fruits have fructose, the fructose is interwoven with the fruits' fiber and is therefore digested more slowly than fructose from other sources. Please note, fructose and high fructose corn syrup are two completely different beats. The latter should be viewed as extremely harmful like a man with a loaded gun.

Therefore, contrary to the advice of pundits that state you can eat all the fruits you want because of the robust nutrient content including various vitamins, minerals, antioxidants and other synergistic nutrients, fruits should be a staple of a healthy diet, but only eaten in moderation. Weight Watchers is simply wrong to assign fruits '0' points, In fact, type two diabetics are told to limit their fruit intake to no more than 15 grams at a sitting because more than that may be problematic. (That's a whole other topic for another day.)

Nevertheless, fruits have plenty to offer, particularly in regards to antioxidants, but do note, that many, if not most, of the same healthy nutrients found in fruits can also be found in vegetables. For examples, the beta-carotene in melons can be found in carrots and yams; lycopene in watermelon can be found in tomatoes (although technically a fruit because it grows on trees,); anthocyanins in blueberries can be found in eggplant; phytosterols and polyphenols can be found dispersed in both groups. The list goes on.

Fruit skins can be good sources of insoluble fiber, helping move things along in the gastrointestinal track and can also contain flavonoids, which are plant secondary metabolites that have antioxidant capabilities that may diminish inflammation. Fruits are also contain other not as fully studied nutrients, like pectins, B-Cryptoxanthin, and A-carotene, which can be in apples. As with other nutrients, they also occur in vegetables.  One area of limited research is the synergistic affects of all the different nutrients found in all the different fruits.  Either way, fruits are a tasty and sweet alternative to less desirable man-sweetened foods.

Argument 3: Fruit calories add to weight gain

The final argument against fruits is the calories they contain. It's true, virtually everything we eat contains calories and fruits are no exception. Even though the theorem of calories in/caloires out is not perfect because not all calories are processed the same because of the fiber content of the food they come from, it is true that fruits, if eaten in large quantities can contribute to weight gain.  It's not the fruits themselves that are causing the weight gain; its the totality of what you are eating.  So as long as you go easy on other foods, your weight loss plans can easily accommodate some measured amount of fruit calories.

Argument 4: They can only be eaten before meals as they will ferment in your intestinal tract after meals

It is simply a myth that you can't eat fruit after meals. You can.  The fermentation arguments are pue rubbish. I searched the entire clinical study database back to the 1950s and couldn't find a single valid study to support such nonsense.
(Don't take my word for it. Read this from the University of Missouri:

http://extension.missouri.edu/cass/documents/Nutrition%20and%20Health/New%20trend%20of%20eating%20fruit%20only%20on%20an%20empty%20stomach%20is%20poor%20advice.pdf

The flip-side: Eat only fruits

Some people have gone to the other extreme and have taken to a mostly fruit diet. Steve Jobs tried and failed to cure his cancer with a mostly fruit only diet.  (See my previous blog on fruits and cancer prevention, which can be found at http://mdprevent.blogspot.com/2012/11/do-fruits-and-vegatables-prevent-cancer.html)

These fruit obsessed dieters claim they possess more energy and feel healthier. This is not surprising because the fructose in fruit is a carbohydrate that fuels energy. But as I wrote above, too much fructose is not a good thing as it can overwhelm the liver and eventually raise blood glucose to levels that precipitate large amounts of insulin release that can predispose to diabetes. Fructose breaks down to substances that can lead to glucose or blood sugar production.

My four golden rules of eating healthy

So in summation, let me finish with my four golden rules of eating healthy.

1. Don't eat more than you need to feel reasonably full.
2. Make sure that the combination of foods eaten over a course of a week contain all the essential nutrients your body needs to function properly.
3. Avoid or severely limit exposure to chemicals and highly processed ingredients stripped of most nutrients, and definitely avoid products that contain many of such ingredients rolled into one.
4. Loosely monitor your total salt, fat, sugar of any kind including fructose, and calorie intake to levels that work for your body. If you are not sure what those levels are, discuss them with your physician.

The final analysis

Fruits have been a staple of the human and pre-human diet for time immemorial.  Yes, its true that fruits may not be of the same nature and quality than they were tens or hundreds of thousands of years ago, but they are still awfully darn good. They offer many key essential nutrients, but as with most foods, you can overdue eating them.  They are a good part of a comprehensive approach to healthy eating.

By the way, do avoid fruit juices that are robbed of most of the fruits' fiber and have concentrated fructose.  However, contrary to the popular belief, the reason to avoid fruit juices is not because fruit lose most of their nutritional value during the juicing process. (See
http://www.ncbi.nlm.nih.gov/pubmed/9806122)

So now that you know the facts, you can figure out when and how much to eat, and enjoy fruit on your own.  Bon Appetite.

Vitamin D Takes A Hit

Faithful readers of this blog (May 18 and August 29) have read my railings against Vitamin D for some time now. It never made sense to me that so many Americans were deemed to be Vitamin D deficient nor did it make much sense that as people got heavier that their blood test for Vitamin D would report lower levels although they wouldn't develop any deficiency symptoms. I even raised the question if it was possible that fat stored Vitamin D (fat soluble) is available to the body when needed.  While this question remains unanswered, the question of what defines a Vitamin D deficiency just got a new answer and I think it makes sense.

The Institute of Medicine (IOM) just revised the guidelines for what defines a Vitamin D deficiency.

First, a little about the IOM.  The Institute of Medicine (IOM) is an independent, nonprofit organization that

works outside of government to provide unbiased and authoritative advice to decision makers and the public. 

Established in 1970, the IOM is the health arm of the National Academy of Sciences, which was chartered under President Abraham Lincoln in 1863. Nearly 150 years later, the National Academy of Sciences has expanded into what is collectively known as the National Academies, which comprises the National Academy of Sciences, the National Academy of Engineering, the National Research Council, and the IOM.

Under the new IOM guidelines, you are considered to have adequate Vitamin D levels if your level is above 20 ng/mL. The previous level was 30 ng/mL. In one fell swoop, the IOM has essentially removed almost all Americans from the category of being Vitamin D deficient. 

You will no doubt hear push-back from those quarters that make money peddling Vitamin D and related advice, but you should essentially ignore them. The IOM is trustworthy.

So if you didn't have enough reasons yet to push aside your multivitamins and Vitamin D supplements, perhaps this one will do the trick for you.

For the umpteenth time, eat whole foods including a wide variety of vegetables, fruits, beans, nuts, seeds, whole grains and Wild Salmon and you will consume all the vitamins, minerals, antioxidants and all the other health promoting nutrients you need for a healthy mind and body. Get 15-30 minutes of sun each day (earlier or later in the day and avoid reddening) and Vitamin D is also well covered. (You also get it from Wild Salmon.)

The key to a healthy life is to eat healthy every day.

Vitamin D Takes A Couple Of More Hits

Two new studies challenge the sweeping hysteria about the need to supplement with Vitamin D.

In one retrospective study looking at Medicare records, researchers could find no link between Vitamin D deficiency and macular degeneration. Based on this study, if you are self-prescribing Vitamin D to treat your macular degeneration, I would strongly consider stopping.

The second study involved men with prostate cancer who are on hormone depleting therapy. This therapy can lead to osteoporosis so it was always thought wise for these men to supplement with Vitamin D and calcium. This study shows that not only doesn't adding these two supplements help, but they may actually be increasing the severity of the cancer. That's on top of the calcium's effects on adding to the risk of calcification of the arteries and heart attacks.

So based on this information you would say that it is probably best to avoid Vitamin D supplements. But wait, there's more. In April 2012, a study showed that high dose Vitamin D supplementation in patients with low risk prostate cancer seemed to help the patients do better with lower Gleason scores, one of the biomarkers for prostate cancer. But wait again.  In this study, involving 52 patients, led by D.T. Marshall of the Medical University of South Carolina and colleagues, 55% did better, 11% had no change, and 34% did worse.

My read on such a study is to basically ignore it because the number of participants was too low, a good percentage got worse and we know little else about their diets, etc.

So what's the answer on Vitamin D? I say sun. It's the only natural way to increase your Vitamin D levels. Of course, don't burn yourself, but 15-30 minutes a day strategically spread out should avoid any such problems in most people. However, that may not be YOU, so if you can't spend even that amount of time in the sun, your next best choice is wild salmon. If you can't or refuse to eat wild salmon, then fortified foods are your next best choice before supplements.

Yesterday, I reviewed 300 study headlines on supplements, particularly about their antioxidant effects, on pubmed.com, and read about 40 abstracts of some of the studies. This effort fortifies my belief that supplements just aren't cracked up to be what their manufacturers and marketers want YOU to believe.

But I also confirmed something else. The studies showed consistently that even with fruits and vegetables, once your body has the vitamins, minerals, and nutrients it needs, giving it more does nothing. It's like filling a canister. Once it's filled, any more added is just spillover. The principle here is that more of a good thing is not better when it comes to your nutritional state. That's the biggest problem I think posed by most supplement products. They operate mostly on the principle of get more to play it safe. More vitamins, more minerals, more antioxidants. YOU don't need more that YOU need and as recent studies suggest, more may not be safe for YOU.

The real take away from all three studies quoted above is that Vitamin D supplementation may not be the panacea that many proclaim it is on a daily basis. Tread cautiously, my friends, when it comes to taking supplements and heed the Latin phrase, Caveat Lector, "Let the reader beware." That includes reading my blog with a bit of caution as well. Nothing written here should be construed as medical advice. The only medical advice you should heed is from a doctor that knows your medical history personally and discusses treatment with YOU directly.

The Only Thing I Know For Sure Is That We Need To Keep Learning

About 30 years ago, I read an article about agriculture that had a profound impact on my thinking. The article was about soil erosion and basically stated that what had long been considered an incontrovertible truth about how to avoid soil erosion turned out to be the exact opposite. The idea that something held as an absolute truth could prove to be absolutely wrong has given me pause to think about such 'truths' to this day.

Thirty years later, a new study about exercise emerges that reminds me of what we consider absolute truths may not be so. For as long as I can remember, exercise has been associated with increasing your metabolism. It's been widely believed that exercise contributes to weight loss by burning calories and increasing your metabolism, which is believed to keep revving and burning calories even during the cool down phase.  While certain people argued that exercise was not an effective way to lose weight because they were unsuccessful losing weight despite much exercise, it was still a tenet of the weight loss movement. For example, Weight Watchers allows you to add extra "points" based on the amount of exercise you do.

The new study, which is a wonderful study, titled Hunter-Gatherer Energetics and Human Obesity, (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0040503) studied the Hadza tribe of hunter-gatherers in Tanzania. Strapping members of the tribe with a GPS device and having them swallow so-called doubly labeled water, a liquid in which the normal hydrogen and oxygen molecules have been replaced with versions containing tracers, researchers were able to quantify their levels of physical activity, energy expenditures and metabolic rates. What they discovered is groundbreaking!

The study showed that contrary to popular belief, exercise slows down one's metabolic rate so that calories burned are actually far less than expected.  What's amazing is that this is intuitive and yet for so long everyone believed otherwise. Think about it for a moment. If your body doesn't eat for several hours, we think (I'm now officially afraid to say anything for certain any more; well, maybe some things) your metabolic rate slows down as your body tries to conserve energy, as it doesn't know when energy will be replenished. Applying that same principle to exercise, when the body senses a loss of energy consumed by increased activity, it makes sense that it will slow down its burn rate to conserve energy.

This doesn't mean that you aren't burning calories and you can't lose weight by exercising. It simply means that you burn less than you think, which means don't think you can eat a lot more because you had a good exercise session.

By now you couch potatoes are turning to your spouses or friends and smugly telling them you were right all along about exercise. Well not so fast.  Exercise is still critical to good heart and brain health. Exercise keeps the heart functioning well and exercise has been shown to be as effective as anti-depressants in treating many cases of mild to moderate depression. But that's not all. Two new studies published online in the Archives of Internal Medicine support the tremendous impact of exercise on lowering the risk of death among diabetic patients, and that weight training may reduce the risk for the disease even without aerobic activity.

Quoting medpagetoday.com, "In a large prospective trial, moderately active patients with diabetes had a lower risk of total mortality compared with those who were completely inactive...according to Diewertje Sluik, MSc, of the German Institute of Human Nutrition in Potsdam, and colleagues. And in a separate prospective study, men who did weight training only at least 150 minutes per week had a 34% lower risk of developing diabetes to begin with ...according to Frank Hu, MD, PhD, of the Harvard School of Public Health in Boston, and colleagues."

I also previously wrote about a study that shows that exercise can return the inflexible blood vessels of pre-diabetics to normal as well.

So while exercise is not the great weight loss panacea it was once thought to be, it is still a critical component of a healthy lifestyle. Keep exercising, but more importantly, if you want to stay slim or lose weight avoid the four whites--white sugar, white flour, white pasta, and white rice. If you watched 60 Minutes this past Sunday, you now know that some scientists view sugar as toxic and cancer causing. Just another good reason to choose whole foods like fruits, vegetables, nuts, beans, and whole grains. And of course, don't forget my favorite, Wild Salmon.  Bon appetite!

A Hodgepodge of New Studies

Making Sense of Two Recent Testosterone Studies:

I am always trying to make sense of the studies I come across. In the past couple of days, I came across two studies involving testosterone, the male hormone. One study showed that overweight men who suffered from hypogonadism (a medical term which describes a diminished functional activity of the gonads, the testes in males) who received testosterone lost weight; the other study showed that men who suffered from hypogonadism who lost weight increased their testosterone to a level where they no longer had hypogonadism (incidence of hypogonadism went from 20% to 11%, about a 50% improvement).

After reading the two studies, I had to ponder for a while how they related to each other and then it came to me. Although I claim no absolute certainty in these conclusions, it seems that for certain overweight men, increasing testosterone, either endogenously (from within) or exogenously (from outside) helps them lose weight. Given the choice, it would seem better to naturally increase a hormone as opposed to getting it from some other derived source. The best way to do so if you are overweight is to change your diet to the a mostly plant-based diet, increase your exercise to moderately-intense 150 minutes per week, and get at least 7 hours of sleep a night.

Are Vitamin D Blood Tests Always Accurate?

Apparently not. A recent study showed that 40% of the time, blood-labs misdiagnose Vitamin D deficiency by reporting lower than actual levels. This may not be true for all labs or all types of equipment used. The equipment/tests that seemed to be the worst offenders were the Architect and Centaur-2 tests. The liquid chromatography/mass spectrometry (LC/MS) test is the gold standard and can generally be relied upon. So the next time you have a test, ask what equipment they are using and consider going to another lab with LC/MS equipment for greater peace of mind.


Is There A Link Between Vitamin B6 and Heart Disease?

A new study shows a link between low Vitamin B6 levels and increased risk for heart disease. The study does not show causality, which means it isn't clear if the low Vitamin6 causes the heart disease or the heart disease causes the low Vitamin B6. It is possible that the inflammation often seen in heart disease may decrease blood levels of the vitamin. Nevertheless, it is important to maintain adequate levels of all vitamins, including B6, so I include the reference table below for your edification.

This table is not meant to be a recommended diet; rather, it is meant to give you a representative sample of sources of Vitamin B6 in regularly available foods.  A healthy diet is one that contains fruits, vegetables, nuts, legumes (beans), whole grains, and fat from fatty fish like Wild Salmon and Wild Cod. It can also include some olive oil, limited red wine, and very occasional chicken or meat. This is often referred to as the Mediterranean Diet and it still seems to pack the most bang for the buck.
Food	Milligrams (mg) per serving	Percent DV*
Chickpeas, canned, 1 cup	1.1	55
Tuna, yellowfin, fresh, cooked, 3 ounces	0.9	45
Salmon, sockeye, cooked, 3 ounces	0.6	30
Chicken breast, roasted, 3 ounces	0.5	25
Breakfast cereals, fortified with 25% of the DV for vitamin B6	0.5	25
Potatoes, boiled, 1 cup	0.4	20
Turkey, meat only, roasted, 3 ounces	0.4	20
Banana, 1 medium	0.4	20
Marinara (spaghetti) sauce, ready to serve, 1 cup	0.4	20
Ground beef, patty, 85% lean, broiled, 3 ounces
Waffles, plain, ready to heat, toasted, 1 waffle	0.3	15
Bulgur, cooked, 1 cup	0.2	10
Cottage cheese, 1% low-fat, 1 cup	0.2	10
Squash, winter, baked, ½ cup	0.2	10
Rice, white, long-grain, enriched, cooked, 1 cup	0.1	5
Nuts, mixed, dry-roasted, 1 ounce	0.1	5
Raisins, seedless, ½ cup	0.1	5
Onions, chopped, ½ cup	0.1	5
Spinach, frozen, chopped, boiled, ½ cup	0.1	5
Tofu, raw, firm, prepared with calcium sulfate, ½ cup	0.1	5
Watermelon, raw, 1 cup	0.1	5

*DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet. The DV for vitamin B6 is 2 mg for adults and children age 4 and older. However, the FDA does not require food labels to list vitamin B6 content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.