How the Standard American Diet Promotes Depression and Deadly Disease

I recently heard a fascinating Science Friday segment with Dr. Andrew Weil, dealing primarily with depression and its causes, and how to fix it.  But interestingly, two of the most common causes -- vitamin D deficiency and omega-3 deficiency -- are also at the root of the big three deadly diseases: cardiovascular disease, cancer, and neurodegenerative disease.  That’s because those diseases, like depression and in fact like most diseases, are caused or exacerbated by inflammation.

Take 25 minutes and listen to the whole episode.  Here are a few quotes from it:

Quoting Dr. Andrew Weil:

Most people in my experience seem to think that they’ll be happy if they get something they now don’t have... Many people imagine that positive moods depend on external circumstances, and that’s not a good place to have it linked to.

The notion that a human being should be constantly happy is a uniquely modern, uniquely American, uniquely destructive idea... Many parents think that it’s their job to make kids happy all the time.  We’re not supposed to be happy all the time.  Our moods are supposed to vary.  They’re not supposed to vary so extremely that they disable us, but I think it is perfectly normal to have lows as well as highs, and there may be even some value in those experiences.

A much better goal to strive for is to be content.  Contentment is something that comes from within, and is relatively independent of external circumstances.

One of the research findings that I find very interesting is that the more people have, the less content they seem to be.  There is a clear correlation of depression with affluence.  And we’re seeing an unprecedented epidemic of depression, in our country especially, but in the developed world generally.  Some of this is manufactured by the medical-pharmaceutical complex.  The pharmaceutical companies have been very effective at convincing people that ordinary states of sadness are now matters of imbalanced brain chemistry which needs to be treated.  I think that’s spurious. [...]

I think in essence the depression epidemic represents a mismatch between the kind of life our genes have prepared us for, and the kind of life most of us actually live.  One clue is that major depression is virtually unknown in hunter-gatherer societies.  You can’t find a case of it in Papua New Guinea.  So what’s different there?  Well, everything.  People in those cultures are living close to nature, they enjoy strong tribal and community support, they’re eating natural diets, not industrial food, they’re getting plenty of physical activity. [...]

On the physical level, the strongest evidence we have is for exercise and for supplemental fish oil.  Both of these interventions work as well as antidepressant medication for mild to moderate depression.  I think they’re even very helpful as adjunctive measures for severe depression. ... These long-chain omega-3 fatty acids [in fish oil] have a great influence on brain function.  One of them, DHA, is the major constituent of cell membranes, neuronal membranes.  And if that’s deficient in the diet, as it is generally in the North American diet, brain health suffers.  So we have very strong evidence for not only the antidepressant effects, but I’d say generally the brain-protective effects of supplementing the diet with omega-3s.  I recommend that everybody take 2-4 grams of supplemental fish oil a day, whether or not you eat fish. [...]

We’re getting a tremendous overload of omega-6s today, mostly from refined vegetable oils; this is heavily present in industrial food.  The more omega-6s you consume, the more omega-3s you need to consume in order to get tissue levels up to where they need to be.  So I think the main thing is that our omega-3 sources have been reduced, and our omega-6 intake has greatly increased, and this puts us at a great disadvantage biochemically. [...]

There is a disturbing and growing body of evidence that the major class of antidepressant drugs, the SSRIs, selective serotonin reuptake inhibitors, don’t work so great.  In fact, they barely can be distinguished from placebo, even in severe depression.  And it may only be in very severe depression that they show any advantage.  There is also great concern about a new problem just coming to light; it’s called tardive dysphoria, which means lingering depression -- caused by the drugs.  We were always taught that depression, however severe it is, is self-limited, that it resolves itself.  Well, it doesn’t anymore.  And one reason why it may not is because the drugs produce the very problem they’re meant to treat.  And this is so logical; it’s similar to what you discussed earlier about antibiotics and germ resistance.  When you push on the body with an outside force, it pushes back; this is called homeostasis.  It’s a basic truth of physiology.  If you increase serotonin at neural junctions with a drug, the body responds over time by producing less serotonin and dropping serotonin receptors.  And therefore, it gets you into a worse situation.  It’s like trying to treat acid reflux with drugs that suppress acid: you take it away, and you have a worse problem than you did to begin with.  So the drugs may create their own need...

If you’ve been on these drugs for a year, it’s worth finding a practitioner who can help give you a schedule to wean yourself off while using the other measures that I recommend.  And if you have mild to moderate depression, I would really urge you to find out about the other things you can do first, before you try medication.  And that not only includes the things we’ve discussed; it may include getting your vitamin D levels checked, because there’s a clear correlation with low vitamin D and poor emotional health. [...]

One of the things that was new for me in researching the book is the connection between inflammation and depression. ... Farmers have long known that when domestic animals become sick, usually with infectious illnesses, they show a characteristic pattern of behavioral changes, and these are called sickness behavior.  They include immobility, loss of appetite, loss of interest in socializing with others of their kind, loss of interest in sex -- changes that are strikingly similar to the changes that human beings show who have major depression.  Farmers assumed that this was due to fatigue, caused by illness.  But in the 1950s, it was found that sickness behavior is mediated by a bloodborne factor.  You can take blood from an animal with this behavior, inject it into a healthy animal, and that animal shows the same behavior.  Nobody knew what it was; it was called Factor X for 20 years.  And then in the 1970s it was identified as cytokines, a group of regulatory proteins used by the immune system to regulate inflammation.

Some of these cytokines later became purified and available for medical use like interferon for the treatment of chronic hepatitis, and interleukin-2.  When these are administered to people for medical treatments, the most severe side effect is extreme depression and suicide. ... So this has led to the cytokine hypothesis of depression, which I find very compelling, and it is that there is a link between upregulated inflammation and cytokines, and depression.  In animals who are sick, this is an adaptive response: the cytokines affect the brain, and cause behavioral changes that probably favor healing.  It makes more energy available to the immune system.  But I think this is a really interesting connection; it opens new avenues for both preventing and treating depression by following an anti-inflammatory lifestyle. [...]

For years I’ve been recommending an anti-inflammatory diet as the best strategy for optimizing health, extending longevity, reducing overall risk of disease.  And I have devised an anti-inflammatory diet; you can find this in the book or on my website drweil.com; it’s a version of the Mediterranean diet, for which we have great evidence of general health benefits, and I’ve tweaked it to make it even more effective.  But the theory here is that all of the major chronic diseases -- cardiovascular disease, cancer, neurodegenerative disease -- begin as inflammatory processes.  And I think most people in our culture go through life in pro-inflammatory states.  There are many reasons for that: genetics, stress, exposure to environmental toxins.  Diet plays a huge role.  The mainstream diet, which is heavy in industrialized food-like stuff, is strongly pro-inflammatory.  It gives us all the wrong things: the wrong fats, the wrong kinds of carbohydrate, and it’s deficient in all that can protect us from the damage of inflammation.  And now, there is this new connection that our emotional health may also be tied here, so that following an anti-inflammatory diet and lifestyle may offer great protection as well as a new treatment strategy for managing depression. ... And the simplest step, the first step of an anti-inflammatory diet is simply to avoid eating refined, processed, and manufactured food.

Fortunately, it’s easy to fix two of the main drivers of inflammation, which are vitamin D deficiency and omega-3 deficiency.  You can get proper vitamin D levels by simply going outside in the noonday sun for about 20 minutes per day a couple of times per week during the summer, or taking ~5000 IU of vitamin D3 in supplement form a couple times per week during the winter months.  And you can get adequate omega-3 intake by eating fish like salmon and herring a couple times per week, or taking a few grams of fish oil (the kind containing EPA and DHA) as often.

But as Dr. Weil explains, regarding omega-3 intake, you also have to consider the opposing type of fat, which is omega-6.  Both are essential, but omega-6 is pro-inflammatory whereas omega-3 is anti-inflammatory, and it’s the ratio that matters: you want to consume about the same amount of each.  Unfortunately, the Standard American Diet is nowhere near this ideal 1:1 ratio; instead, it’s more like 10:1 or 20:1, with omega-6 far outnumbering omega-3, hence the epidemic of inflammation and inflammatory diseases.  So it’s not enough to simply boost your omega-3 intake; you also need to decrease your omega-6 intake, which means ditching the industrial seed oil -- commonly known as vegetable oil -- that’s present in so many packaged foods, not to mention commonly used as cooking oil and salad dressing.  Boosting your omega-3 intake won’t do any good if you’re regularly consuming typical amounts of soybean oil, canola oil, corn oil, etc.