Epidemiological Studies

I spend hours every day reading studies, articles, and researching health-related matters. When I find a new publication or exploration of a topic, I get excited to dive in. That being said, some studies and articles are more useful than others.

One type of study that is used frequently to make health claims and guide public policy is an “epidemiological study”. Epidemiology is the study of a set population, or group of people, to develop correlations or inferences.

The problem is that these do not prove anything. When we find a strong correlation between factors, we should use that as a starting point to conduct further research. An epidemiological study, by itself, should never be the basis for making health policies.

Let me give some examples.

Epidemiology suggests that soy is a healthy incorporation in a diet. This is due to the fact that Asian countries consume high amounts of soy on a regular basis and don’t experience the same health problems as Western nations.

However, no other factors are taken into account.

The soy that Asians consume has not been genetically modified to the same extent as ours, nor has it been grown in soils depleted of minerals. Also, most Asian dishes use fermented soy or the bean in its natural state.

Asian cultures consume more wild-caught fish (high in anti-inflammatory omega-3s), sea vegetables (loaded with vitamins and minerals), and opt for white rice, with less anti-nutrients and gut-damaging proteins than typical “heart-healthy” whole grains such as wheat and oatmeal.

Historically, Asians don’t consume as much processed food as Americans. They don’t cook in corn or canola oil, they don’t have packaged foods at every meal, and they don’t go out to eat as often.

And finally, they are far more active – walking, biking, and taking the stairs as part of daily life.

Because of these factors, we cannot confidently say that the consumption of soy in Asian countries is the cause of their better health.

When we look at soy mechanistically, we find phytoestrogens that have the potential to skew hormone levels, leading to fat-storage and growth of cancer cells. It is extremely high in inflammatory omega-6s. Take into consideration our growing practices, extensive refinement process, and consumption of soy byproducts, and soy consumption in the US no longer seems as safe.

Another example of epidemiology lacking substance:

In March of this year, there was a headline stating: “Animal protein-rich diets could be as harmful to health as smoking”. These news reports were based upon two studies: one epidemiological study of over 6000 adults and one study of mice in a laboratory.

The results of these studies suggested that a high protein diet (over 20% of calories) was “positively associated with diabetes-related mortality”. When you look at the numbers, one person in the “high-protein” group (consisting of over 1000 individuals) died from diabetes.

The lead researcher running this study owns a plant-derived protein supplement company…explaining the claim that only animal-protein is dangerous.

Some other issues:

There was no way to control for protein quality. There has never been a study showing negative outcomes from consumption of wild-caught fish, grass-fed beef, or eggs from pasture-raised chickens.

The mice that experienced growth of cancer tumors were implanted with melanoma cells before the study began. Plus, the study found that high protein consumption was “not associated with all-cause, CVD, or cancer mortality”. Therefore, the protein-cancer correlation was in fact disproved.

Finally, diet was self-reported. The average participant reported consuming 1,800 calories a day…30% lower than the national average. This suggests major under-reporting.

So, even though the study was riddled with flaws, and actually found no increased risk from animal-protein consumption, the results were phrased to dissuade individuals from consuming meat.

To get back to my original point – epidemiology is used too often to prove a pre-existing belief, promote a political agenda, or increase profits.

By itself, epidemiology is no different than trying to claim that the number of birds flying over a particular region somehow determines cancer rates in that area.

Certainly we should use any research tactic available to ask questions and form a hypothesis…but ultimately, we need to examine issues in every way possible.

Once we’ve investigated mechanisms, done cohort studies and some “food-diary” studies with pictures, it’s time to form a hypothesis and conduct a blinded, crossover, metabolic ward trial to draw some real conclusions!
correlation

The Most Nutritious Foods

As many of you know by now, I try to consume the most nutritious foods possible. However, I’ve never listed exactly what foods provide the most nutrients per serving.

Advertisements claim that certain foods are important nutritionally. Markets assign numbered scores to various products. Most of these rating systems, such as NuVal and ANDI, are inaccurate for a number of reasons.

First, they look at nutrients that are not essential for life, and conversely, overlook nutrients that are necessary for life. Second, they draw from disproved nutritional norms, such as dietary cholesterol and saturated fat being “bad”. Thirdly, they are designed by agricultural companies or individuals with a bias.

Scientists, such as Loren Cordain and Mat Lalonde, have done extensive work in the last few decades to redesign nutrient rating systems. They set aside non-essential nutrients in food and focused purely on what the body must consume from outside sources.

The body cannot produce the following:

Fatty Acids: Omega 3 and Omega 6

Amino Acids: isoleucine; leucine; lysine; methionine; phenylalanine; threonine; tryptophan; valine; histidine

Vitamins: A; Bp (choline); B1 (thiamine); B2 (riboflavin); B3 (niacin); B5 (pantothenic acid); B6; B7 (biotin); B9 (folic acid); B12; C; D; E; K

Minerals: calcium; chloride; chromium; cobalt; copper; iodide; iron; magnesium; manganese; molybdenum; nickel; phosphorus; potassium; selenium; sodium; sulfur; zinc

These nutrients were plugged into the following formula to determine nutrient density:

(sum of essential nutrients per serving) ÷ (weight per serving)

I’d like to make a few points before posting Mat’s nutrient density list.

First, the database he drew from did not have complete data for certain nutrients.

The database did not differentiate between preformed vitamins and their final form. Vitamin A, “beta-carotene”, in sweet potatoes and carrots, must be converted to “retinol”, found in egg yolks and liver. Vitamin K1, found in green leafy vegetables, requires conversion to K2, found in grass-fed dairy.

There was no way to account for bioavailability of nutrients. Most grains, legumes, nuts, and seeds contain high levels of phytates which prevent absorption of nutrients and minerals.

Finally, and most importantly, the diet, age, and lifestyle of animals were not specified. Grass-fed beef, raised on open pastures, is much healthier than corn-fed beef, raised in stalls that restrict movement. Also, mature ducks having more nutritional value than baby ducks.

Taking this unavailable data into consideration, we can assume that most animal products would move up a few spots. This is because most plants have limited amino acids and fatty acids, and the vitamins found in vegetables must be converted or activated.

Without further ado, the ranking of nutrient density averages for the food groups:

1.) Organ Meats and Oils
2.) Herbs and Spices
3.) Nuts and Seeds
4.) Cacao
5.) Fish and Seafood
6.) Pork
7.) Beef
8.) Eggs & Dairy
9.) Vegetables (raw & unprepared)
10.) Lamb, Veal, and Wild Game
11.) Poultry
12.) Legumes
13.) Processed Meat
14.) Vegetables (cooked, canned, blanched, pickled)
15.) Plant Fats and Oils
16.) Fruit
17.) Animal Skin and Feet
18.) Grains and Pseudocereals (cooked)
19.) Refined and Processed Fats and Oils
20.) Grains (canned)
21.) Processed Fruit

Many people will be surprised by how low grains appear on the list. The nutrient value of raw grains would place them in the top 5. However, our bodies cannot digest raw grains. Taking nutrient loss during cooking and expansion of grains (1/4 cup raw rice = 1 cup cooked rice) into account, their value decreases dramatically.

I was quite surprised to see herbs, spices, and cacao near the top of the list. I always considered these foods to be enjoyable additions to a healthy diet, but not the most valuable sources of nutrients.

Two final notes regarding this list:

It is not a requirement to eat the most nutritious foods all the time. Certain nutrients, such as activated vitamin A (retinol) and selenium (abundant in Brazil nuts) are actually toxic in high doses.

Second, as previously mentioned, this rating system only looks at essential nutrients. Many vegetables contain antioxidants and fiber that can improve health, even though they are non-essential for life.

I would recommend consuming foods higher on this list and keeping your meals full of vegetables.
For Mat Lalonde’s complete presentation, follow this link to YouTube.

Matheiu Lalonde has a PhD in Organic Chemistry and a postdoctoral degree in Inorganic Chemistry from Harvard. He teaches, lectures, and is the Science Safety Officer at Harvard’s Department of Chemistry and Chemical Biology. I have to give him credit for the motivation behind, and information in, this post.

I hope this sets aside all confusion of what is best to eat.

Keep in mind that human-run studies can be flawed, correlations from epidemiological studies can be weak, and research can be conducted to prove a point, rather than discover the truth, but the actual make-up of foods cannot be disputed!