Lots of people have made money selling diet and nutrition books, often with completely contradictory information. And now there is a new TV show adding even more confusion to the topic. ABC just started showing My Diet is Better Than Yours which “features celebrity trainers coaching average Americans to lose weight and get in shape. Each trainer brings his/her own individually designed and wildly diverse diet and exercise plan to their contestant, and works with them to change their lives.” I haven’t seen the show yet, more to come on that. For this post, I’m going to focus on my recommendations for healthy eating – not weight loss per se.

Medical researchers really don’t really know with certainty what we should eat, but they have some good ideas based upon decades of research. The challenge researchers face is that the long-term effects of our diet on our health are really hard to measure. It’s one thing to feed mice a low carb diet or a high fat diet and see what happens to them over the course of their short lives. It’s quite another to do the same to people. And as has been seen time and time again, the information we glean from studying animals doesn’t often apply to humans.

I suspect that another issue limiting our ability to study diet and health is that there are likely metabolic differences between people. Although researchers tend to conduct research under the assumption that our bodies all pretty much work the same when it comes to nutrition, I think this is a mistake. In many circumstances it is true that our bodies work the same. We all have very similar anatomy and can have blood and parts interchanged with others, for example. But it is quite likely there are some fundamental differences in how individuals break down and use nutrients from our diet. It’s probably not as simple as eating for our blood type as a famous book has suggested, but I think there is some truth to the overall concept that different people likely benefit more from diets rich in certain compounds.

Maybe some of this variation is genetic; maybe some is environmental. We know that people metabolize alcohol differently (depending on our genetics and whether we consume alcohol regularly or not) and that our livers metabolize certain medications differently.

And we also know that bacteria in our intestinal tracts vary a lot from person to person and that these microbes (called the microbiome) play a very large role in why two people might respond very differently to the same diet. Not only is it that the food one eats might be broken down more easily by certain bacteria, but also eating certain types of foods over a long period of time can lead to the growth of either healthy or unhealthy bacteria which have their own independent influences on our health. Researchers are just starting to understand this better, but I predict that this will be a huge shift in how we look at nutrition in the coming years.

But let’s get back to what we do know. First of all, pretty much all research indicates that eating lots of fruits, vegetables, nuts, seeds and legumes is healthy for our bodies. These should all be the cornerstone of what all of us eat. Not only do these foods provide us with lots of essential nutrients, including vitamins and minerals, they also provide us with lots of fiber and other nutritional compounds that researchers continue to uncover and report: exotic sounding things like lycopenes, biotin, and retinoids. These substances, both known and currently unknown, are thought to play a very substantial role in reducing our risk of developing cardiovascular disease, cancer, dementia and many other conditions. The very things that make an apple red or a blueberry blue are the things that help keep us healthy.

Also, experts are generally in agreement that one should limit simple carbohydrates in our diet – things made with white flour and sugar, white rice and pasta. Although both cheap and relatively filling, these do not provide fiber or other nutrients and they are quickly broken down into simple sugars. These sugars cause spikes in insulin, which can cause us to feel hungry not long after eating and can lead to increases in body fat.

And what about fat? Should you use oils? Well, yes. Particularly plant-based oils like olive, canola, and coconut. These have a lot of nutritional value, particularly in providing essential fatty acids like omega-3 and omega-6.

I think that all of the above are reasonable guidelines that most people should follow. In all of these things, moderation is the most important consideration. I don’t like to tell people that they can never eat white bread, or cake or drink a soda. But these processed should be occasional treats rather than the cornerstone of one’s diet. And limiting calories is also important both for weight control and also for longevity.

The real controversial issue is animal protein, including eggs and low fat dairy. The data here is really mixed and I think that this is a truly unresolved issue. Certainly people who do not want to eat meat for ethical or religious reasons can have a very healthy and complete diet (with the exception of getting enough vitamin B12 which is found almost exclusively in animal products). But I think that the real question that remains is whether most people should or should not follow a vegan diet. On the one hand, lean animal protein is a filling and balanced source of amino acids and is rich in vitamin B12. On the other hand, some data shows that when our bodies break down animal proteins from any source, the byproducts create some cancer causing compounds.

So in summary, my recommendations (until we can create a truly personalized diet) are as follows:

• Eat mostly plant-based foods.
• Limit simple carbohydrates.
• Stay away from processed foods.
• Think about limiting animal protein.
• And don’t eat too much.