Eating Too Much Fruits Is Not Good?

The blogger’s note: In response to an email regarding “Health Hazards Associated with All-Fruit Diet (see http://articles.mercola.com/sites/articles/archive/2013/02/11/all-fruit-diet.aspx) , Dr JB Lim comments as follows:

From: lim juboo

Sent: Wednesday, May 29, 2013 12:35 AM

I really do not know the correct answer. Nutrition is so very complex and very confusing these days since the days I studied it at the University of London, and at Cambridge.

Over the last 5 decades, so many, many newer knowledge has been added to it through world-wide research. As a result of this avalanche of knowledge in nutrition, we do not know which direction to take as many findings contradict earlier studies.

On just cancer and nutrition alone, it is estimated that no less than US $ 5,000 million has been spent every year on this issue, let alone thousands of times more spent on nutrition and other diseases. The results of all these findings are very confusing even to us as nutritionists, researchers, medical and health professionals or other health-care providers.

A search of the literature on fructose and pancreatic cancer itself gave different directions and opposite findings, generating different opinions. All the claims seem valid from their study designs.

In any case, both glucose (grape sugar or dextrose) and fructose (fruit sugar) are monosaccharide (simple sugars) but we know they take different metabolic pathways.

None of these pathways show any evidence that fructose causes pancreatic or any other form of cancers while other sugars do not? There is just not good enough evidence to this claim even in lab investigations, let alone in large scale clinical studies and in epidemiological studies. Where are the large population evidence-based studies to support this?

Birds, bats, squirrels and many forest animals that feed exclusively, or mainly on fruits in the forests are not more prone to pancreatic cancers or other cancers than other animals that feed on nuts, seeds, leaves, bamboos or thrive on other animals. Why should man then get cancer by eating mainly on fruits?

In any case, I hardly know of any human beings who eat only fruits, and no cereal grains or vegetables. Our body knows best. The body is part of Mother Nature. It will signal to the body that an exclusively fruit-diet is unpleasant and cannot be sustained for long. Humans will tend to avoid what is unpleasant. Normally, this is part of the body’s defense mechanism – the body’s signals, although sometimes it remains silent and does not respond to a threat especially if a stimulus is continuously sustained as a unhealthy lifestyle habit (examples: smoking, high sugar and high salt intake and stress).

If a person who eats fruits alone, where is he going to get his proteins, fat soluble vitamins, including adequate amounts of B group of vitamins? Fruits are not rich in these nutrients.

What is worse, he will suffer from a fatal disease called “megaloblastic anemia” because of the lack of vitamin B 12 and folic acid, especially vitamin B12 which is not found in fruits and vegetables. Vitamin B 12 is present only in animal foods, especially shell fish, eggs, milk, cheese, beef, mutton, chicken and especially in raw liver. A person who eats only fruits alone will soon die of this fatal disease far faster and much sooner before he can even get pancreatic or other cancers. Vegans are specially prone to suffer from megaloblastic anemia, and is fatal unless corrected by regular injections of vitamin B12 (cobalamin).

It is also known that fructose requires half the insulin to metabolize than for glucose. In other words, less insulin is required weight-for-weight for these sugars, and hence fructose is less taxing to the beta cells of the islets of Langerhans in the pancreas that produces the insulin.

If that is so, fructose in fruits should protect the pancreas from pancreatic cancer because it requires less insulin. But this article sent to me claims the opposite. It was quoted: “So if you want to prevent cancer, or want to treat cancer, it is imperative that you keep your insulin levels as low as possible.”

So, my point of argument is, if you want to keep your insulin level as low as possible, then taking fructose found in fruits and corn syrup should keep the insulin lower because, as I said, fructose requires half the amount of insulin to metabolize than glucose.

We know that cancer cells feeds on all sugars, not just on fructose, but we are uncertain which type of sugars it prefers to feed on first? A search of the literature does not conclusively say that it prefers fruit sugar (fructose) over grape sugars (glucose).

Then we also need to consider what about cane sugar (table sugar) or sucrose which is a disaccharide. We know that on hydrolysis, sucrose yields a mixture of monosaccharides containing glucose and fructose? What about that now? Does cane sugar causes pancreatic cancer because of the fructose? Which is which now – fruits or table sugar?

However we do know that diabetes with high glucose in the blood does promote cancers, not just pancreatic cancer. Hence diabetes may be one of the causes of cancers while non-diabetic reduces the risk of cancers since diabetes, obesity, heart disease and cancers are interlinked. As I said, cancer cells need sugars to thrive. By way of this reasoning, a diabetic who has higher blood glucose levels suggests he would have lesser insulin (or less effective insulin) to control his blood sugar. Then he should be less prone to cancer? But the opposite is true. A diabetic is more prone to cancer than a non-diabetic. So the insulin may have nothing to do with this, while a higher glucose (not fructose) in his blood has much to do to promote and feed the cancer cells. So can we conclude it is the glucose in the blood, and not fructose that feeds and promotes the cancer, because normally it is glucose and not fructose that is in the blood unless a person eats only fruits or only corn syrup? Isn’t this logical?

If this is the case, a diabetic with lesser insulin would be less prone to cancers than a non-diabetic with greater amounts of insulin. Unfortunately this article gave the opposite view.  It advises: “It is imperative that you keep your insulin levels as low as possible”. In other words, you need to have diabetes (low insulin, higher blood sugar) in order to prevent or treat cancer? Is that what the author of that article meant?

Which is which now – the devil or the deep blue sea? But scientists are aware that cancer cells thrive on sugars and not fats, both can be used as sources of energy to the body. But the body will use up sugars, be they will use up glucose, fructose or galactose (milk sugar) first, and if not available, then the body will metabolize the fat reserves. This is well-known in nutrition and biochemistry. It is also known that cancer cells feed on simple sugars, but not fats. But normal cells can utilize both – simple sugars as well as triglycerides from the digestion of fats.

So knowing this fact, we get another set of people who now capitalize on another idea. These people then claim that you can “cure” cancer by taking a diet solely on fats, and no sugar, because these people believe that cancer cells that can only thrive on sugars and not on triglycerides (fats) will die if a diet has no sugar in it. To my mind this is even more illogical.

Such a dietary regimen is called a ketogenic diet, meaning a diet high in fats, sufficient protein, but no or very low in sugars and carbohydrates. Such a diet has been used in medicine to treat difficult-to-control epilepsy, or refractory epilepsy.

But a diet with high or only fats is very difficult to consume, and very difficult to sustain, besides developing a medical condition called ketosis. This (ketosis) causes a lot of unpleasant symptoms such as headaches, weight loss (as in Atkins diet), mood swings, nausea, loss of appetite, dehydration, smell of acetone (nail polish) in saliva and breadth.

This is due to the presence of ketones (acetoacetate and beta-hydroxybutyrate) in the blood, urine and breath from fats metabolism instead of carbohydrate or sugar.

Most ketones can be used by the body including the brain, except acetone which gives that ‘sweet smell” of nail polish in the breadth. But ketosis may then develop into a more serious condition called ketoacidosis especially those with type 1 diabetes. So again, which is which?

Do we want all these very unnatural and unpleasant symptoms to occur by consuming a diet that is ketogenic (high fat, low sugar) just because we believe it can prevent or treat cancer?

Believing in this is no different from believing that cytotoxic drugs (chemotherapy) can prevent and treat cancer, when in standard text-books on pharmacology it is very clearly stated there, that all cytotoxic drugs are a carcinogen (an agent that causes cancer).

Again, which is which now – the devil or the deep blue sea?

Pancreatic cancer is one of the most aggressive forms of cancer, and there have been many theories of its causes, but none is satisfactory. I don’t think there is only one simple cause of cancer, example, blaming it on fructose in fruits?

This is not wise, as it may cause confusion to a lot of people. Such a claim may discourage people from eating fruits which in fact work the opposite way. Fruits and vegetables have tremendous health benefits in preventing cancers because they are so rich in cancer-fighting phyto chemicals and antioxidants.

In my professional opinion, fruits do not cause cancers because people blame them on fructose alone. Cancers have multi factorial causes – from hereditary and oncogenes, dietary exposure, viruses, radiation, chemicals (example: smoking), compromised immunity, stress, etc, etc. Cancers are a multiple diseases, and is not caused by any single factor by itself.

For instance, oncogenes,such as the SRC gene (just an example) has been shown to cause a number of cancers, such as colon, liver, lung, breast and pancreatic cancer. There is no fructose involved here.

I think the opposite is true. Fruits, especially the highly coloured ones protect against cancers, not cause them. In fact there are many other foods, that are not even fruits (examples turmeric, lemon grass, broccoli, cauliflower, cabbage, and all the cruciferous vegetables) that protects against cancers including pancreatic cancer, and may even cure cancer (example: Sabah snake grass).

To sum up my opinion, anyone, whether or not he or she is a doctor, a qualified nutritionist (including BOGUS ones), who advises others not to eat fruits, and vegetables or any food containing fructose because they “cause (pancreatic) cancers” should be put into a mental asylum immediately and locked up there forever before they do more damage to the health of others with their half-cooked knowledge taken from one study especially an ill-designed one.

jb lim