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Startling Research Findings: A Newly Discovered Cause of High Blood Pressure and Obesity?

By Dr. Mercola

If you have been reading my recent articles about sugar, you will probably recognize Dr. Richard Johnson from previous articles.

Dr. Johnson is one of the physicians on the cutting edge of sugar metabolism research today, his focus being on how the overabundance of sugar in the American diet -- particularly fructose -- is causing obesity, hypertension, diabetes, and a number of other health problems in staggering numbers.

In this lecture, Dr. Johnson takes a more historical approach to obesity and cardiovascular disease, reviewing the important uric acid connection and some interesting evolutionary findings related to the way humans metabolize sugar.

Cardiology is a Relatively NEW Field

Obesity rates have paralleled sugar consumption trends in Western civilization. Although the obesity epidemic is relatively recent, obesity is not a new phenomenon.

In 1860, the prevalence of a BMI (body mass index) of 30 or higher (which defines obesity) was 1.6 percent among 50 year-old men. By 1900, it had tripled, and it has sharply increased over the past century.

Like obesity, hypertension was also rare prior to the twentieth century:

  • In 1900, only 5 percent of the population had a blood pressure of 140/90 or higher.
  • By 1939, 10 percent of adults had blood pressures above 140/90.
  • Today, 31 percent of adults are hypertensive.

Prior to 1940, there was no such thing as a cardiologist because there was no need for them. That was only 70 years ago!

The first reported angina was in 1929. In 1950, there were 500 cardiologists in the United States. Now there are 35,000 -- and they perform more than one million heart surgeries annually.

What is driving this eruption of cardiovascular disease?

One key factor: the explosion of sugar in the Western diet.

Sugar used to be quite expensive. It was a nonessential food item reserved mostly for the wealthy. Prior to 1800, Americans were consuming only about 4 pounds of sugar per person, per year. By 1800, that number had increased to 18 pounds as sugar plantations began to emerge. And by 1900, it was 90 pounds.

And sugar consumption has literally exploded since then -- our entire society is dependent on a substance that offers no nutritional value at all.

Diabetes Was Linked to Sugar Back in the 1800s

Diabetes has shown similar historical trends.

In 1892, there were just two cases of diabetes per 100,000 people, according to a famous medical textbook by Sir William Osler, The Principles and Practice of Medicine. Today, the rate is 9 percent across all age groups, and sadly one of every three children is diabetic.

When you look at the numbers of adults aged 20 and over, the incidence rate is almost 11 percent. And when you look at seniors aged 60 and up, the prevalence is over 23 percent!

The statistics are even more grim when it comes to the prevalence of pre-diabetes (impaired fasting glucose).

Almost 26 percent of U.S. adults over the age of 20 are pre-diabetics, and more than 35 percent of seniors, 60 and older.

All in all, the reality is that one in every four Americans is now either diabetic or pre-diabetic.Even in the 1800s, it was recognized that diabetes was related to sugar consumption.

Dr. Haden Emerson, one of the first epidemiologists and a public health commissioner of New York, wrote a brilliant paper about the rise in diabetes in New York City. In it, he commented that people who got diabetes were wealthy, sedentary, white, and he posed that sugar was driving it, according to the information presented by Dr. Johnson.

Today, the average American is consuming 56 gallons of soda and 152 pounds of sugar-based sweeteners annually. Soda consumption has risen by 70 percent since 1977. Ten to 20 percent of children’s calories come from sugar -- and the top 20 percent of sugar-addicted children are getting 40 percent of their calories from sugar every single day.

It is no accident that childhood obesity is at a record high and life expectancy for the youngest generation is, for the first time, lower than that of their parents.

The worst type of sugar you can ingest is fructose, which may surprise you because it is derived from fruit.

Fructose Turns You Into a Uric Acid Factory

It’s been known for ages that meats and purine-rich foods can raise uric acid, but it turns out that one of the most profound ways to raise uric acid is by consuming the simple sugar fructose.

Regular table sugar is called sucrose and it is made up of two simple sugars, fructose and glucose, that are linked together.

Glucose and fructose are different types of sugar, originating from different foods, and they are metabolized using completely separate pathways. Glucose is utilized by every cell in your body -- in fact, your body was designed to use it for energy.

But fructose breaks down into a variety of waste products that are bad for your body, one of which is uric acid. As it turns out, uric acid drives up your blood pressure.

How does it do this?

Uric acid inhibits the nitric oxide in your blood vessels, and nitric oxide helps your vessels maintain their elasticity. Nitric oxide suppression leads to increases in blood pressure.

In fact, 17 out of 17 studies demonstrate that elevated uric acid levels lead to hypertension.

Thanks to Dr. Johnson’s research, we now know that fructose generates uric acid within minutes of ingestion. High levels of uric acid are normally associated with gout, but it has been long known that people with high blood pressure and kidney disease, and people who are overweight, often have elevated uric acid levels.

It was thought this increased uric acid resulted from the disease, but it appears now that it may have been CAUSING it!

Not surprisingly, uric acid levels have been increasing for the past hundred years.

When your uric acid level exceeds about 5.5 mg per dl, you have an increased risk for a host of diseases, including:

This is exactly why I am so passionate about educating you about the dangers of fructose! I am thoroughly convinced it’s one of the leading causes of a great deal of needless suffering from poor health and premature death.

One of the people who truly opened my eyes and educated me on this issue is Dr. Robert Lustig, Professor of Pediatrics in the Division of Endocrinology at University of California in San Francisco.

If you still haven’t watched his excellent lecture on the dangers of fructose and other sugars, I strongly recommend you take the time to do it. (I’ve published it in two parts. Click here for part 1, and here for part 2.)

What Happened 17,000 Years Ago That Changed Your Physiology?

Dr. Johnson describes an evolutionary turn we took that set us all up for the uric acid problem we are seeing today.

The first apes appeared during the early Miocene epoch, of which there were more than 100 different species. Then, about 17,000 years ago, the Earth began to cool.

As our planet began to glaciate, the water level of the Tethys Sea fell, exposing a land bridge that allowed mammals such as apes, rhinos and giraffes to migrate into Europe. As winters worsened, there was a massive extinction (the mid Miocene extinction) in which 30 percent of the mammals died off, including most of the primates.

The geological record tells us that, coinciding exactly with this cooling cycle, a massive asteroid hit Europe with the force of 3 million Hiroshima bombs, which placed additional stress on mammals. This is EXACTLY when a mutation appeared that gave some primates an advantage: the uricase mutation1.

Apes that had this genetic mutation had a survival edge because their increased uric acid levels, in response to their diet, caused them to build up body fat. The primates that lacked this important mutation simply didn’t survive the long, bitter winters.

Dr. Johnson has worked with Peter Andrews of the Natural History Museum in London in putting together the anthropological evidence of this mutation.

Other sources hypothesize that this gene gave these primates an advantage by a slightly different mechanism -- by raising their blood pressure during the low-salt conditions that prevailed during that period2 3

Either way, it is clear that today this uricase mutation is NOT serving you now!

You don’t need the extra body fat this mutation causes, since you aren’t trying to stave off starvation during a “nuclear winter” where food is scarce and conserving calories gives you a survival advantage.

Glucose Makes Fructose Even More Potent!

Fructose consumption clearly causes insulin resistance, whereas straight glucose does not. Insulin resistance can eventually lead to full blown diabetes.

Interestingly, glucose actually accelerates fructose absorption. So when you mix glucose and fructose together, you absorb more fructose than if you consumed fructose alone. This is an important piece of information if you are struggling to control your weight.

Remember, sucrose, or table sugar, is exactly this blend -- fructose plus glucose.

Is Fruit Bad?

If you are craving something sweet, your best bet is to reach for an apple or a pear. And if you give yourself a sugar holiday for even a couple of weeks, you will be amazed at how much those cravings will decrease. But be sure and count the grams of fructose and keep your total fructose from fruit below 15 grams per day as you are sure to consume plenty of "hidden" fructose in the other foods you will be eating.

You can use the table below to help you count your fructose grams.

Fruit Serving Size Grams of Fructose
Limes 1 medium 0
Lemons 1 medium 0.6
Cranberries 1 cup 0.7
Passion fruit 1 medium 0.9
Prune 1 medium 1.2
Apricot 1 medium 1.3
Guava 2 medium 2.2
Date (Deglet Noor style) 1 medium 2.6
Cantaloupe 1/8 of med. melon 2.8
Raspberries 1 cup 3.0
Clementine 1 medium 3.4
Kiwifruit 1 medium 3.4
Blackberries 1 cup 3.5
Star fruit 1 medium 3.6
Cherries, sweet 10 3.8
Strawberries 1 cup 3.8
Cherries, sour 1 cup 4.0
Pineapple 1 slice 
(3.5" x .75")
Grapefruit, pink or red 1/2 medium 4.3
Fruit Serving Size Grams of Fructose
Boysenberries 1 cup 4.6
Tangerine/mandarin orange 1 medium 4.8
Nectarine 1 medium 5.4
Peach 1 medium 5.9
Orange (navel) 1 medium 6.1
Papaya 1/2 medium 6.3
Honeydew 1/8 of med. melon 6.7
Banana 1 medium 7.1
Blueberries 1 cup 7.4
Date (Medjool) 1 medium 7.7
Apple (composite) 1 medium 9.5
Persimmon 1 medium 10.6
Watermelon 1/16 med. melon 11.3
Pear 1 medium 11.8
Raisins 1/4 cup 12.3
Grapes, seedless (green or red) 1 cup 12.4
Mango 1/2 medium 16.2
Apricots, dried 1 cup 16.4
Figs, dried 1 cup 23.0

My Recommended Fructose Allowance

As a standard recommendation, I strongly advise keeping your TOTAL fructose consumption below 25 grams per day.

However, for most people it would actually be wise to limit your fruit fructose to 15 grams or less, as it is virtually guaranteed you will consume “hidden” sources of fructose from most beverages and just about any processed food.

Fifteen grams of fructose is not much -- it represents two bananas, one-third cup of raisins, or just two Medjool dates!

Since the average 12-ounce can of soda contains 40 grams of sugar, at least half of which is fructose, this can of soda ALONE would exceed your daily allotment of 15 grams -- plus it offers you absolutely nothing nutritive, only empty calories.

Reducing sugar in your diet can be tough. After all, sugar is just as addictive as cocaine!

In his book, The Sugar Fix, Dr. Johnson includes detailed tables showing the content of fructose in different foods -- an information base that isn’t readily available when you’re trying to find out exactly how much fructose is in various foods. I encourage you to pick up a copy of this excellent resource. 

If you feel you must have a sweetener, here are a few guidelines to follow:

  • Avoid ALL artificial sweeteners.
  • Avoid all conventional agave and high fructose corn syrup
  • Limit sugar of all types as much as possible. You can buy pure glucose (dextrose) as a sweetener for about $1 per pound, which has none of the adverse effects of fructose if used moderately. It is only 70 percent as sweet as sucrose, so you’ll end up using a bit more of it for the same amount of sweetness, making it slightly more expensive than sucrose -- but still well worth it for your health.
  • Use high quality agave that has fructose in it's conjugated from. You can also use raw honey in moderation or avoid it completely as it is 70 percent fructose which is higher than HFCS. However the fructose is not in its free from so that moderates the damage. But each teaspoon of honey has nearly four grams of fructose so you will want to carefully add the total grams of fructose (including fruits) and keep them under 15 grams per day.
  • Use regular stevia in moderation, but avoid stevia-based sweeteners like Truvia and PureVia because they have undergone more processing.
  • Lo Han is another excellent natural herbal sweetener.
  • Exercise can be a very powerful tool to help control fructose in a number of ways. If you are going to consume fructose it is BEST to do so immediately before, during or after INTENSE exercise as your body will tend to use it directly as fuel and not convert it to fat Additionally exercise will increase your insulin receptor sensitivity and help modulate the negative effects of fructose. Lastly exercise will also help to blunt your appetite and control your sweet tooth.

If you have insulin issues, high blood pressure, high cholesterol, diabetes, or if you’re overweight, I suggest you avoid all sweeteners, including stevia, since any sweetener can decrease your insulin sensitivity.