Marc Joseph Nutrition - Blog

In a study published in the Journal of Clinical Investigation, researchers found that mice missing a key prostate cancer tumor suppressor gene were much more likely to survive with a high omega-3 fat, low omega-6 fat diet.

Specifically, survival rates in the study were:

• 60% for the mice fed a high omega-3 fat diet (1-to-1 omega-6 to omega-3 fat ratio)
• 10% for the mice fed a low omega-3 fat diet (20-to-1 omega-6 to omega-3 fat ratio)
• 0% for the mice fed a high omega-6 fat diet (40-to-1 omega-6 to omega-3 fat ratio)

In addition to improving survival times, omega-3 fatty acids slowed both the progression of cancer cell formation and tumor growth.

As one of the study’s co-authors notes, the implications are significant:

“This suggests that if you have good genes, it may not matter too much what you eat,” said Chen, a professor of cancer biology. “But if you have a gene that makes you susceptible to prostate cancer, your diet can tip the balance. Our data demonstrate the importance of gene-diet interactions, and that genetic cancer risk can be modified favorable by omega-3 PUFA.”

The bad news: The tumor suppressor gene absent in the mice in this study is estimated to be missing in 60% to 70% of human metastatic cancers. So, counting on good genes may not be a good bet.

The good news: Since prostate cancer cells are typically slow-growing, improving the omega-3 / omega-6 fat intake balance is one factor that may play an important role in determining whether one ultimately develops the disease.

Possible Mechanism

As discussed in an earlier post, a higher omega-3 / omega-6 fat intake tends to promote the production of anti-inflammatory immune system modulators (e.g., prostaglandin PGE-3), while a high omega-6 / omega-3 fat intake tends to promote the production of pro-inflammatory substances (e.g., prostaglandin PGE-2 and cytokines IL-6 and TNF-alpha).

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In a study published in the journal Psychosomatic Medicine, researchers at Ohio State found that individuals with the highest blood levels of Omega-6 fats relative to Omega-3 fats were more likely to suffer from depression and to have higher levels of inflammation-promoting compounds in their bodies.

Specifically, as depressive symptoms increased in the study participants, higher Omega-6/Omega-3 ratios were associated with higher levels of inflammatory cytokines (immune system messengers) TNF-alpha and IL-6. Conversely, Omega-3 fats help promote the production of anti-inflammatory substances, such as prostaglandin PGE-3, and are linked to lower rates of depression.

Omega-3 fats are found primarily in fish oil and flaxseed oil (although only fish oil has the Omega-3 fats EPA and DHA in their final bioavailable forms). Omega-6 fats are found primarily in the diet in vegetable oils, such as soybean, corn, sunflower, and safflower oil, and also in the form of arachidonic acid in meat, dairy, and eggs.

* An exception to the primarily pro-inflammatory Omega-6 fats is gamma-linolenic acid (GLA), which is found in borage, evening primrose, and black currant oils, and helps to promote the production of anti-inflammatory prostaglandin PGE-1.

Changing Fat Intake Patterns & Implications

Historically, people eating a hunter-gatherer type of diet consumed about 2 to 3 times the amount of Omega-6 fats relative to Omega-3 fats. Today, in most Western diets, largely as the result of higher intake of refined vegetable oils in packaged and restaurant-prepared foods, that ratio is more like 15 to 20 to one.

The pro-inflammatory state that results from eating such a diet has negative implications not only for conditions such as depression as highlighted in this study, but also for many other conditions, such as diabetes, heart disease, arthritis, allergies and asthma, prostate cancer, skin disorders, and more.

Diet-wise, this imbalance in Omega-6/Omega-3 fat intake is likely one of the biggest factors contributing to chronic disease. Taking a fish oil supplement that has been tested for contaminants and reducing the consumption of foods prepared using vegetable oils are two ways to help improve this balance and restore a more normal immune response.

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Discover How Nutrition Can Make a Difference in Your Life …

Marc Joseph Nutrition

For a while now, non-fish sources of Omega-3 fat DHA (docosahexaenoic acid), such as the one produced from microalgae by Martek Biosciences, have been produced and incorporated into many consumer products, such as:

• Infant formulas
• Dairy products
• Nutrition bars
• Dietary supplements
• Etc.

To-date, though, there hasn’t been a non-fish source of EPA (eicosapentaenoic acid), the other primary Omega-3 fat shown to have important health benefits.

Recently, a UK company called Water4life introduced an algae-derived Omega-3 supplement that contains both DHA and EPA.

A couple of notes on it:

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Adding to a growing body of evidence that links Omega-3 fatty acid intake with healthy bone growth, a study just out in the American Journal of Clinical Nutrition (AJCN) found that healthy teenage boys with higher serum levels of Omega-3 fatty acids, especially DHA (docosahexanoic acid), had significantly greater bone mineral density accrual between the ages of 16 and 22.

This result is important, as bone growth during the teenage years is key to building a high peak bone mass that may reduce the risk of developing osteoporosis later in life.

In a related earlier study published in the AJCN, researchers found that among older adults age 45 to 90, a higher ratio of Omega-6 to Omega-3 fatty acid intake was associated with a significantly lower bone mass density at the hip.

Omega-3 fats EPA and DHA are found primarily in fish oil, while the main sources for Omega-6 fats in the diet are vegetable oils (corn, soybean, sunflower, safflower). Most people eat far too much Omega-6 fats relative to Omega-3 fats. The estimated ratio in Western diets is 15:1, whereas a ratio between 1:1 to 4:1 is believed to be optimal.

How Fat Intake Affects Bone Growth

The exact mechanism for how higher levels of Omega-3 fats and/or a lower Omega-6/Omega-3 fat intake ratio may assist bone growth is not yet entirely understood. However, an accompanying editorial to this month’s study in the AJCN, makes some interesting observations:

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Researchers from the from the Salk Institute for Biological Studies and the La Jolla Institute for Allergy and Immunology have found what could be a potentially important link between inflammation and cancer:

[T]he study, published in the January 26 issue of the journal Cell, shows that what scientists thought were two distinct processes in cells—the cells’ normal development and the cells’ response to dangers such as invading organisms—are actually linked. The researchers . . . say that the linkage of these two processes may explain why cancer, which is normal growth and development gone awry, can result from chronic inflammation, which is an out-of-control response to danger.

Here’s a visual depiction of that concept:

Normal dialogue between cell defense and development (left) and chronic inflammation leading to hyperactive developmental signaling that may promote cancer (right). (Credit: Alexander Hoffmann, UCSD)

Specifically, the research team found a protein that is common to both inflammation and cancer development pathways:

[The research] team showed that these pathways are not distinct from one another because they are linked by a protein called p100. They found that inflammation leads to an increase in p100, but that p100 is also used in certain steps in development. Therefore p100 allows communication between inflammation and development.

Importance of Balance

Your body needs some inflammation to fend off invaders (bacteria, viruses, fungi, etc.), but excessive, chronic inflammation is detrimental and implicated in many chronic conditions (e.g., cancer, diabetes, heart disease, rheumatoid arthritis, inflammatory bowel disease, etc.). You need a balance.

To be clear, the inflammation I’m referring to is not necessarily visible or felt. It’s not like a red, swollen joint or a scratch on your arm. This inflammation is chronic and low-level, like invisible fires simmering underneath the surface. But over time, this inflammation causes damage to the cells, tissues, and systems of your body, and in turn, leads to the development of disease.

The Role of Nutrition

Nutrition can play an important role in helping to keep inflammation in check. For example:

• Omega-3 fats, as found in fish oil, can help to reduce inflammation. These fats produce substances (prostaglandins) that inhibit inflammation in cells throughout the body.
• Conversely, excess consumption of most Omega-6 fats, as found in vegetables oils, such as the corn and soybean oils used in high amounts in processed and restaurant-prepared foods, can promote the production of pro-inflammatory prostaglandins.
• One Omega-6 fat, gamma linolenic acid (GLA), found in borage, evening primrose, and black currant oils, actually can help to promote the production of anti-inflammatory prostaglandins, as well as encourage normal cell death (apoptosis) — a primary process gone awry in cancer.
• Trans fats promote chronic inflammation.
• High sugar and refined grain intake, and the resulting chronically elevated blood glucose and insulin levels, is another primary cause of chronic inflammation.

There are numerous other substances found in both foods and supplements that can help to reduce and/or manage chronic inflammation, including:

• Vitamin D (primary source: sunshine)
• Tumeric
• Ginger
• Boswellia
• And many others …

Avoiding chronic inflammation is one of the most important steps you can take in helping to reduce the risk of developing many chronic diseases, such as cancer, heart disease, diabetes, cognitive decline, arthritis, and more.

A couple of more studies just released that again suggest omega fatty acids may be helpful in slowing cognitive decline:

Omega-3 fatty acid treatment in 174 patients with mild to moderate Alzheimer disease

This study found that patients with very mild Alzheimer’s disease (AD) who supplemented with omega-3 fatty acids (2.3 g/day)experienced significantly slower rates of decline in mental function. However, individuals with mild to moderate AD didn’t improve.

This result reinforces the importance of early intervention and prevention. Once damage to the brain is significant (as seen in moderate cases of AD), a single helpful nutrient like omega-3 fats, although not detrimental, is likely to not necessarily lead to great improvement.

Dietary supplementation of arachidonic and docosahexaenoic acids improves cognitive dysfunction.

Arachidonic acid is an omega-6 fat, while docosahexaenoic acid (or DHA) is an omega-3 fat. Most people get plenty of omega-6 fats in the diet, as they are found in high quantities in vegetable oils used in processed and restaurant-prepared foods. Arachidonic acid (ARA) is also found in high amounts in red meat and egg yolks. On the other hand, most people are deficient in omega-3 fats, such as DHA and eicosapentaenoic acid (EPA), which are found in fish oil.

This second study found that individuals with mild cognitive impairment who supplemented with only 240 mg of ARA and DHA experienced improvements in both immediate memory and attention scores. As in the earlier study, no improvement was seen in individuals who had already developed AD.

For omega-3 fats DHA & EPA, it’s important to make sure that the source (fish or supplements) is low in contaminants, such as heavy metals and PCBs. Tested fish oil supplements are your best bet there.

You can learn more about the important roles of omega-3 fats in disease prevention and treatment here.

And, you can learn more about ways to preserve and improve cognitive function here.

A somewhat sad commentary on the slow adoption in the U.S. of a simple, inexpensive, and effective way to help prevent and treat heart disease using fish oil:

Every patient in the cardiac care unit at the San Filippo Neri Hospital [Rome, Italy] who survives a heart attack goes home with a prescription for purified fish oil, or omega-3 fatty acids.

“It is clearly recommended in international guidelines,” said Dr. Massimo Santini, the hospital’s chief of cardiology, who added that it would be considered tantamount to malpractice in Italy to omit the drug.

In a large number of studies, prescription fish oil has been shown to improve survival after heart attacks and to reduce fatal heart rhythms. The American College of Cardiology recently strengthened its position on the medical benefit of fish oil, although some critics say that studies have not defined the magnitude of the effect.

But in the United States, heart attack victims are not generally given omega-3 fatty acids, even as they are routinely offered more expensive and invasive treatments, like pills to lower cholesterol or implantable defibrillators. Prescription fish oil, sold under the brand name Omacor, is not even approved by the Food and Drug Administration for use in heart patients.

“Most cardiologists here are not giving omega-3’s even though the data supports it — there’s a real disconnect,” said Dr. Terry Jacobson, a preventive cardiologist at Emory University in Atlanta. “They have been very slow to incorporate the therapy.”

The article goes on to note that since the prescription fish oil is not licensed in the U.S. to prevent heart disease (only to treat high triglycerides), community doctors don’t learn of its potential preventive use and insurance companies don’t provide reimbursement.

Amazing, isn’t it?

The majority of Americans, not just heart attack patients, don’t get adequate intake of omega-3 fatty acids. Fish is by far the best food source of these healthy fats, but there are clearly toxicity risks. Supplements are a much safer route and help to ensure that you get a regular supply.

The prescription fish oil capsules are fine. They’re concentrated to have about three times more omega-3 fatty acids than most non-prescription products. But they’re also a lot more expensive and require a prescription.

Non-prescription products, as long as they’re tested for contaminants, are just as good. And some manufacturers even make concentrated formulas to reduce the number of necessary pills.

Most brands of fish oil are tested for contaminants. You can check many brands here.

Given the many benefits of omega-3 fatty acids in helping to prevent and treat disease, hopefully we’ll their use increase in medicine going forward — and not just in Europe.

These were a few of the headlines after the recent release of two studies examining the health benefits and risks of eating fish:

Seafood benefits found to outweigh risks (Boston Globe)

Eat more fish, study urges, despite toxin risk (Reuters)

Seafood not your health foe, studies say (SJ Mercury News)

The first study, a meta-review* completed by researchers at the Harvard School of Public Health and published in the Journal of the American Medical Association, boldly suggested that regular fish consumption could reduce the risk of heart attack death by 36 percent and the overall risk of death by 17 percent.

(* A meta-review is a review of the existing body of research. Perhaps the Harvard meta-review excluded studies like this one, “Mercury in fish poses heart risk for middle-aged men“?)

The second study, a report completed by the Institute of Medicine (IOM), was more balanced in its review of the research. It concluded only that the regular consumption of fatty fish may reduce the risk of heart disease, while “contaminants that may be present in seafood may pose a risk to some especially susceptible groups of people.”

A More Balanced View

Just reading the headlines, one could easily draw the conclusion that concerns about toxins in seafood are overblown and that there’s really nothing to be concerned about unless you’re a pregnant woman, a prospective mother, or a small child. Fortunately, the NY Times presented a much more balanced perspective in their coverage:

The Harvard study, to be published in the Journal of the American Medical Association today, said the benefits of eating fish high in omega-3’s strongly outweighs risks from contaminants like PCB’s and dioxin found in high concentrations in fish like farmed salmon. Calling those risks “greatly exaggerated,” Dr. Darius Mozaffarian, one of the two authors, said, “Seafood is likely the single most important food one can consume for good health.”

Dr. Marion Nestle, a professor of nutrition, food studies, and public health at New York University, who described the “very sunny Harvard study” as “astonishing,” remains unconvinced. “The report’s conclusion that the risk of death can be reduced by 36 percent is just stunning,” she said. “It would indeed make eating fish the single most important decision you can make for your health. But those of us who have been in nutrition for a long time have seen miracle foods come and go: vitamin E for heart disease, beta carotene to prevent cancer; now it’s fish.”…

…The report from the Institute of Medicine tells the government that much more research is needed. Dr. Malden C. Nesheim, chairman of the institute’s committee and a provost emeritus at Cornell, said, “We are quite cautious because the studies we looked at are not controlled for all the variables, and we can’t distinguish between the effects from omega-3’s or replacement of other foods in the diet.”

The NY Times reporter then exposed some of the behind-the-scenes political maneuvering:

The National Oceanic & Atmospheric Administration [NOAA] had requested the institute’s report because it said consumers were confused about how much and what kind of fish they should eat. The two studies, which conflict in important aspects, seem unlikely to provide much clarity. “The high degree of certainty in one report and the extreme caution in the other,” said Rebecca Goldberg, a senior scientist with Environmental Defense, an advocacy group, “will make people more confused than ever.”

To the surprise of Institute of Medicine officials, NOAA sponsored the hastily called press conference at which the Harvard report was released, even though that study conflicted with the one prepared by the institute. “We’re just trying to make consumers feel good*,” said William T. Hogarth, assistant administrator for fisheries of the National Marine Fisheries Service*, part of NOAA.

[* emphasis added]

Major environmental and groups noticed the inconsistencies as well:

Both reports have come under criticism from environmental groups and from the Consumers Union. “In addition to being concerned about the failure of the JAMA and I.O.M. reports to address the risks of mercury in tuna,” said the consumer organization, “we are also concerned that both reports dismiss concerns about PCB’s in most fish.”

“These reports are urging Americans to eat more seafood as if it were a crisis,” Dr. Goldberg said. “According to NOAA’s own statistics, per capita consumption of seafood has risen from 14.8 pounds in 2001 to 16.6 pounds in 2004.”

Jane Houlihan, the research director of the Environmental Working Group, another advocacy group, said, “The Harvard study reads like an advertisement for the seafood industry.”…

…“Once again pregnant women are being told it’s O.K. to eat tuna,” Ms. Houlihan said. “The reality is, 90 percent of women would exceed government’s level for a safe dose of mercury if they ate six ounces of albacore tuna every week as the F.D.A., E.P.A and now I.O.M. recommend.”

What to Do

Omega-3 fats found in fish clearly are beneficial for heart, brain, and immune system health. There’s a great overview of those benefits discussed in this article, “Omega-3 Fatty Acids: Vital to a longer, healthier life.” And the truth is that the majority of people do not take in adequate amounts of these healthy fats.

Unfortunately, though, many fish are contaminated with toxins such as mercury. Do yourself and your family a favor. Use a simple online calculator like this one to help plan safe seafood consumption.

(While you’re there, ask yourself why government agencies responsible for advising consumers on safe fish consumption haven’t put together such easy-to-use tools? The IOM, in fact, recommended the creation of such tools in their report.)

Better yet, to ensure adequate Omega-3 fat intake, include regular consumption of fish oils that have been tested to be free of contaminants such as heavy metals, PCBs, etc. There’s a good list of safe products here.

Tuna industry sales are down 10 percent over the last year, primarily as a result of consumer concerns about the mercury content of the fish.

A recent Consumer Reports analysis found that canned light-chunk tuna, often believed to be a safer, lower-mercury choice, may actually have at least as much of that metal as albacore (or white-chunk) canned tuna.

The contamination of the fish is certainly not the tuna industry’s fault. The mercury enters the environment primarily through other industries (e.g., coal-fired power plants, cement plants) that release the metal into the air. It then settles into bodies of water, small organisms (e.g., plankton) absorb it and are eaten by larger organisms (e.g., fish), and it accumulates as it moves up the food chain.

That said, based on the mercury levels and the potential risk, especially among children, pregnant women, and women of child-bearing age, it makes sense to avoid/minimize consumption of fish that may be high in mercury and other potential contaminants.

An easy-to-use mercury in fish calculator can be found at GotMercury.org.

(Note: Relying on the calculator alone may not be such a good idea. The calculator uses mercury levels in fish as provided by the FDA. For some fish, the number of fish sampled is very small and/or the samples were drawn many years ago. A good example is light-chunk tuna, which shows an average level of ~0.12 ppm. Yet, as the Consumer Reports analysis showed, the actual level of mercury could be three or more times that.)

In general, I would:

• Steer clear of large, predatory fish such as tuna
• Choose safer forms of seafood, such as wild salmon, tilapia, sardines, herring, shrimp, and clams
• Supplement the diet with tested, contaminant-free fish oil to get adequate amounts of healthy Omega-3 fats on a regular basis