Fish is Not Health Food

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Fish is Not Health Food

 

 

By John McDougall MD

 

Many health professionals and scientists are recommending fish to improve your

health and especially, to reduce your risk of suffering from heart disease.

Japanese are the most-recognized example of a fish-eating population enjoying a

low incidence of diseases common to Americans (heart disease, breast cancer,

diabetes, etc.), and a trim appearance. Plus, people living in Japan have the

longest life expectancy of any country in the world. But, I believe these

advantages are in spite of the fish, rather than because of the fish. Japanese

are healthy primarily because they eat a diet based on rice with lots of

vegetables – fortunately for them; they eat fish only as a condiment.

 

A Muscle is a Muscle

 

Fish is the muscle of a cold-blooded, animal with fins and gills. The major

components of fish are fat and protein. There is no carbohydrate, no dietary

fiber, or no vitamin C in fish. Because many fish are high on the food chain

they are highly contaminated with environmental chemicals – it is not unusual to

read in the newspaper that certain kinds of fish, such as swordfish, tuna, or

shark, contain sufficient levels to be considered a health hazard. For example,

because of their high content of mercury, the Food and Drug Administration (FDA)

has advised women who are pregnant or plan to become pregnant to not eat

swordfish, king mackerel, tile fish, shark, or fish from mercury contaminated

areas.

 

The advantages of fish over beef, chicken or pork are largely mythical1

 

Fish Fat

 

Fish is high in fat – often 60% of the calories come from fat. This fat is

effortlessly incorporated into a person’s body fat – contributing to the risk of

obesity. Fish fat is usually associated with a low risk of cancer. However,

there is considerable evidence that fish fat (omega-3 fat) will increase a

person’s risk of cancer and also will increase the risk of metastasis (spread of

cancer to other parts of the body).2-5 Fish fat is known to paralyze the actions

of insulin and increase the tendency for high blood sugars and eventually

diabetes, known to suppress the immune system, and known to increase the

tendency for serious bleeding (see below under fish oil supplements).

 

Fish Cholesterol

 

Like all animal products, fish are high in cholesterol. Based upon a weight of

100 grams, mackerel contains 95 mg of cholesterol, haddock 65 mg, tuna 63 mg,

and halibut 50 mg. This compares to beef at 70 mg, chicken 60 mg, and pork at 70

mg.1 However, when the comparison is made based on calories, fish (50 mg/100

calories) is much higher in cholesterol than pork (24 mg/100 calories), beef (29

mg/100 calories), or chicken (44 mg/100 calories).1 Comparisons based upon

calories are much more relevant because we eat our diet based upon calories (a

2000 calories diet) rather than based on the weight of the food (a 5 pound

diet). Feeding fish to people, instead of beef, pork or chicken, causes

predictable increases in their blood cholesterol to levels that are virtually

the same.6

 

Fish Protein

 

Fish is high in animal protein and the kinds of protein that make up fish are

very acidic in nature. The high acid load caused by the ingestion of fish

results in bone loss, which eventually leads to osteoporosis.7 Eskimos are among

the highest consumers of fish on Earth; they also have the highest rates of

osteoporosis of any people on our planet. After the age of 40 years, Eskimos of

both sexes have from a 10% to 15% greater bone loss than do whites in the US of

the same age.8 The Eskimos consume up to 2,500 mg of calcium a day, mostly in

the form of fish bones – this large calcium intake is offset by the high protein

content (250 to 400 grams a day) – much of this coming from fish.

 

I have heard it said that the negative effects of protein on bone health are

only caused by synthetic mixtures of proteins devised in the laboratory, and are

not caused by the real foods that people eat, such as chicken, turkey, beef or

fish. People making such statements fail to thoroughly review the scientific

literature (and by no coincidence, most are advocates of high-protein diets).

 

To support their claim of no effect of whole animal foods on bone loss they will

quote the work of Herta Spencer from the mid 1970s. She published 2 often-sited

studies on the subject – one was paid for by the National Dairy Council9 and the

other by the National Livestock and Meat Board.10 Her work has been rightly

criticized because close scrutiny reveals areas of serious inconsistency. For

example, in the study paid for by the National Dairy Council,9 she used

inappropriate subjects and reported conclusions in contrast to her results. Of

the six subjects in the study, one had osteoporosis and the urinary calcium so

low as to suggest calcium malabsorption. Another subject carried a diagnosis of

hypercalcuria (very high levels of calcium in the urine), making his data

invalid. Of the remaining four subjects, three subjects did experience increased

calcium loss during the high protein diet.11

 

Studies on human subjects using whole foods, such as beef, chicken and turkey

have produced negative calcium balances of 77 mg/day.12 In another study, the

addition of 5 ounces of skipjack tuna a day (34 grams of animal protein)

increased the loss of urinary calcium by 23%.13 Furthermore, scientific evidence

shows that the body does not adjust (compensate) with time while on high protein

diets, and the losses continue for as long as the diet is high in animal

protein.14

 

Infectious Agents

 

In the United States of America, seafood ranked third on the list of products

which caused food-borne disease between 1983 and 1992.15 Several illnesses are a

result of toxic algal blooms; for example, the most commonly reported marine

toxin disease in the world is ciguatera – associated with consumption of

contaminated reef fish such as barracuda, grouper, and snapper. There are about

20,000 cases world-wide. Ciguatera presents primarily as diarrhea, abdominal

cramps, vomiting, paresthesias, pain in the teeth, pain on urination, blurred

vision, arrhythmias, and heart block Another common problem from fish is

Scombroid poisoning. This type of food intoxication is caused by consuming

scombroid and scombroid-like marine fish species that have begun to spoil with

the growth of certain types of bacteria. Fish of the Scombridae family are tuna

and mackerel.

 

Environmental Contaminants

 

Fish eat other fish that eat plankton and algae, which are contaminated with

environmental pollutants. Because these chemicals are attracted and concentrated

in the fat of the fish, they become even more concentrated as the chemicals move

up the food chain, by a process known as biomagnification. The fish most heavily

laden with chemicals are those such as the tuna, swordfish and shark, which are

predators of smaller sea life.

 

Unfortunately, those most affected by all this contamination are the ones

highest on the food chain – our unborn and breast-feeding children, living off

of their mother. Polychlorinated biphenyl exposure (PCB) of children born to

women who had eaten relatively large quantities of Lake Michigan fish resulted

in poorer intellectual function of the children, compared to other children,

shown by lower scores on a preschool IQ test, and poorer verbal IQ and reading

comprehension at 11 years of age.17

 

Mercury Contamination and Heart Disease:

 

Methylmercury (MeHg) is a global environmental problem and is listed by the

International Program of Chemical Safety as one of the six most dangerous

chemicals in the world's environment. A recent article in the New England

Journal of Medicine warned that many fish contain such high levels of mercury

that they may actually increase your risk of a heart attack.18 In this study,

toenail clippings from men with a history of a previous heart attack provided

evidence of the person’s accumulation of mercury. Those with high mercury levels

had more than double the risk of a heart attack compared with those who had low

levels.

 

Mercury is known to be toxic to the nervous system and kidneys, but long-term

exposure may also accelerate the development of arthrosclerosis (hardening of

the arteries) by promoting free radical damage to the arteries. Free radicals

are highly reactive species of common substances, such as fats and

LDL-cholesterol, which donate electrons to tissues and cause severe damage

leading to many common diseases. Fish can be a major source of mercury in a very

toxic form called methylmercury. This substance may counteract all the

hypothesized benefits of omega-3 fats on prevention of heart disease.

 

Fish Oil Supplements

 

Unless they have been specially processed to remove cholesterol, fish oils

contain large amounts of cholesterol and will raise the blood cholesterol of

people. Even when the fish oil is purified of cholesterol, the omega-3 fat

itself will cause the LDL-bad cholesterol to rise.19,20 The final results are

published in a study on the effects of fish oil on artery closure, where the

authors concluded, “Fish oil treatment for 2 years does not promote favorable

changes in the diameter of atherosclerotic coronary arteries.”21

 

To get the cholesterol lowering effects of fish oil you need to consume about

2.5 to 3.5 ounces daily, and that represents 675 to 900 extra calories daily.1

Fish fat is easily stored and I have seen patients of mine gain 5 pounds when

they added fish oil to their “heart disease prevention program.”

 

Furthermore, fish oils suppress the immune system, which can promote cancer and

increase susceptibility to viral infections; and can cause severe bleeding.22.23

Fish fat also inhibits the action of insulin, thus increasing a person’s

tendency to suffer from diabetes.24

 

Our Future and that of the Poor Fish

 

I wrote this article just before leaving to go SCUBA diving on the Great Barrier

Reef in Australia. I love fish – I love to watch them and I love to photograph

them, but I do not like to kill or eat them. I am very concerned that fish, in

too many minds, has become “health food.” It is not healthy for humans to eat

and it is certainly not healthy for the fish. I have shown my children the

beauty of the oceans on our many adventures to Costa Rica, Panama, Hawaii and

the Cayman Islands. I worry that my children will not have the opportunity to

show their children the same beauty -- unless we start telling the truth about

fish.

 

Full citations for this article can be found online at

http://www.nealhendrickson.com/mcdougall/030200.htm.