We have all been told for years that the main dietary risk factor for heart disease and stroke is how much saturated fat we eat. We have also been told that eating foods high in cholesterol also increases risk of heart disease and stroke. Evidence is accumulating that consumption of saturated fat increases risk of heart disease and stroke little if at all. Since your body makes cholesterol itself, eating cholesterol rich foods has almost no effect on serum cholesterol. Other aspects of diet have a much greater effect on increasing the risk of heart disease and stroke. In this post I will summarize the evidence and spend some time discussing things we eat and drink that do substantially increase the risk of heart disease, stroke and other chronic diseases.

The Seven Country Study

The most famous study that led to the saturated fat hypothesis was carried out by Ancel Keys. The study started in 1956 and was published in 1978. He looked at the dietary patterns of 7 different countries. The countries included Finland, Greece, US, Italy, Yugoslavia, Netherlands and Japan. He found that saturated fat intake was correlated with increased risk of heart attack and stroke. The country with the lowest saturated fat intake was Crete in Italy, which also had the lowest incidence of heart disease and stroke of the 7 countries. The diet of Crete is the basis for the famous Mediterranean Diet.

Diets of free living humans are notoriously difficult to measure. Keys did his best to accurately determine diet. He had a subset of his subjects in each country weigh their food for a number of days, which is considered the gold standard for dietary studies. The problem with any population study like this is that populations in different countries differ in lots of other ways besides diet. Also diets are complex, so some other factor or factors in diet could account for the low heart disease incidence in Crete. Another problem was that diet was measured in Crete during Lent, when most people did not eat meat. All Keys could really say was that saturated fat intake was associated with heart disease, but he could not say that saturated fat caused heart disease.

People who adhered to the Mediterranean Diet did reduce their population risk of heart disease, but there is a lot more to the Mediterranean Diet than reduced saturated fats. It also includes little added sugar, lots of vegetables and fruit and mostly unprocessed foods. It is not clear that reduction in saturated fat is responsible for the health benefits of the Mediterranean Diet.

The Framingham Study

The next big population study was the Framingham Study. A large group of people in Framingham Massachusetts was followed over many years with surveys about diet, activity, smoking and laboratory measurements of total cholesterol, LDL, HDL and triglyerides among other measurements. Heart attacks, strokes, death from either of these things and death from any cause were recorded in the study group. This was the first large study that implicated cigarette smoking as a cause of cardiovascular disease and cancer. It was also found that the higher the total cholesterol and especially the higher the LDL (low density lipoprotein) the higher the risk of cardiovascular disease. It was also one of the first studies that showed that the higher the blood pressure, the greater the risk of cardiovascular disease. This was a tremendously important and well done study.

The Diet-Heart Hypothesis

The diet-heart hypothesis is that saturated fat is the main dietary cause of cardiovascular disease. It has been very influential over 60 years and is still promoted by the American Heart Association and many cardiologists. Here is the train of thought. The 7 country study implicated saturated fat as associated with cardiovascular disease. It has been found through multiple studies that saturated fat intake raises LDL (so called bad cholesterol). The Framingham study showed that increased LDL was a major risk factor for cardiovascular disease. Since saturated fat raises LDL, therefore saturated fat must cause cardiovascular disease.

That makes perfect sense, so many randomized trials were carried out to nail down the diet-heart hypothesis. Unfortunately, as is often the case with beautiful theories, further randomized trials did not consistently show the expected increase in heart disease from eating saturated fat. The other part of the hypothesis was that eating polyunsaturated fats would decrease the population risk of heart disease. That was based on the observation that consuming polyunsaturated fats decreased LDL levels. Randomized trials have generally failed to consistently show that eating polyunsaturated fats reduces the risk of cardiovascular disease.

Reduced Risk of Cardiovascular Disease in US

Heart disease was epidemic in the US, peaking in the 60’s. Since then, the incidence of heart disease in the US and most other developed countries has decreased by 60%! Scientists debate the cause for this decline. Although saturated fat consumption decreased some, Americans still eat much more saturated fat than the 5% of fat recommended by the American Heart Association. So the fact that we eat somewhat less saturated fat does not explain the remarkable decline in heart disease over the last 60 years. What else changed?

Cigarette Smoking

In the 1940’s half of all Americans said they smoked cigarettes. Smoking began to decline in the US in the 60’s and today only 11.5% of Americans smoke tobacco! This has to be a major factor in the decline of cardiovascular disease (and lung cancer).

High Blood Pressure

High blood pressure is a major risk factor for heart disease. The number of people with high blood pressure successfully controlled on medicine has more than doubled since 1960. This is clearly another major factor in the decline of cardiovascular disease

Trans Fats

The rise of trans fat consumption was an unintended consequence of the heart-diet hypothesis. Because animal fat (mostly saturated fat) was postulated to cause heart disease, the food industry started figuring out how to use vegetable oil to replace lard and butter, which were high in saturated fats. They needed something that would be solid, not liquid at room temperature. They discovered that if they partially hydrogenated vegetable oil, then it would be solid at room temperature and could substitute for lard and butter. They marketed these products as healthier because they were only partially saturated fats, not saturated fats. The medical establishment bought this story and recommended margarine as a substitute for butter and Crisco (the most successfully marketed shortening substitute) as healthier alternatives. I have been unable to find statistics on trans fat consumption in the US, but it was very large.

It turns out that consumption of trans fats markedly increased the risk of cardiovascular disease. For every 2% increase in the consumption of trans fats, heart disease increased by 23%. This is a shocking number! The consumption of trans fats certainly contributed to the epidemic of heart disease in the 50’s and 60’s. The FDA essentially banned the addition of trans fats to food in June of 1978. The elimination of trans fats is almost certainly another major factor in the decline of heart disease.

Interesterification

Since trans fats have been banned, food companies have come up with a new way to make vegetable oil solid and spreadable. It is called interesterification. It is complicated, but the simplest explanation is that it involves changing the arrangement of fatty acids on a glycerol backbone. These are fully hydrogenated fats, so are not trans fats. We know very little about how these new industrial fats affect human health, but the information we do have suggests that these new products may be just as bad for you as trans fats. You would do best to avoid them until we know more. More about how to do this later in this post.

Do we need to limit red meat consumption?

The main risk of consumption of any food is eating too much of it. It is total calorie intake that makes us fat, and being fat increases the risk of cardiovascular disease, diabetes and some cancers. Eating red meat by itself is very unlikely to increase your risk of heart disease as long as your total calorie intake is equal to the calories you burn up. So there is very little health risk to you in eating red meat, but there is a big risk to the environment. Cattle raising worldwide contributes about 16% of greenhouse gas emissions. Here is a link to a balanced discussion of greenhouse gas emissions from cattle raising: Livestock Don’t Contribute 14.5% of Global Greenhouse Gas Emissions.

The other thing to think about when consuming any meat product, including chicken is that almost all the meat you buy in the grocery store comes from giant factory farms, where animals are treated very inhumanely. That in itself is bad enough, but raising all those animals together increases risk of spreading disease to the people who eat them. Antibiotics are used in many factory farms to keep animals from getting sick. This contributes to the evolution of bacteria that are resistant to most antibiotics.

If you are not willing to give up eating meat entirely, try to find locally raised beef, pork and poultry. Farmer’s Markets are a good place to find meat from locally raised animals. It may be a little more expensive, but likely a lot safer.

What about eating fish?

If you are at high risk of cardiovascular disease or have cardiovascular disease then eating oily fish (salmon, sardines, anchovies, herring, mackerel, tuna, swordfish) twice a week reduces your risk of a heart attack by 50%. If you are at average risk, these fish don’t have unusual health benefits but if you like them, it’s fine to eat them. Because most of these fish contain some mercury they should probably be avoided by pregnant women and children. If you get canned tuna, get Pacific Island Tuna at Walmart. It is sustainably caught. Here is a link to an article from the Nature Conservancy about it: The Nature Conservancy. By the way taking fish oil is not nearly as good for you as eating fish.

Highly Processed Foods

There are convincing data that consumption of lots of highly processed foods leads to health concerns ranging from increased risk of obesity, high blood pressure, breast and colorectal cancer, to dying prematurely from all causes.These foods all also contain additives whose health effects have never been adequately tested. How do you recognize them? Just look at the label where the ingredients are listed. If there are more than two things you don’t recognize, put it back on the shelf. Here is an example of an ingredients list from a loaf of bread!

This is not bread you would want to eat! If you mostly stay out of the central aisles of the grocery store you will avoid most highly processed foods. Just be sure to look at the ingredients label before you buy anything.

It is all well and good for me to make these recommendations, but highly processed foods and factory farmed meat are cheap. People who are poor cannot afford to buy anything else. This is only one of the things that have led to the major health inequities that are present in this richest country in the world.

Foods that decrease risk of cardiovascular disease

Fiber

Increased dietary fiber has been shown to decrease risk of cardiovascular disease. This may well have to do with promoting a healthy microbiome in the intestine. Sources of fiber that promote growth of healthy gut bacteria are ones that contain inulin. The highest sources of inulin are leeks, asparagus, onions, wheat, garlic, chicory, oats, soybeans, and Jerusalem artichoke. Sourdough bread (no added sugar, honey, or high fructose corn syrup) is also a good source of fiber. Whole grains, fruits, nuts and vegetables are also good sources of fiber.

Fresh Fruits

Fresh fruits are a good source of fiber and also contain many beneficial nutrients including vitamins and antioxidants. Data from multiple studies show that eating fresh fruit daily reduces risk of cardiovascular disease.

Nuts

Eating a handful of nuts per day reduces your risk of heart disease by 20%. Peanuts are technically of legume, not a nut, but legumes reduce the risk of cardiovascular disease as well. Unsalted nuts are better for you than salted.

Whole grains

Whole grains are also a good source of fiber and other beneficial nutrients. Eating whole grains most days is associated with decreased obesity, diabetes and heart disease. Examples of whole grains are

• Barley.
• Bulgur, also called cracked wheat.
• Farro.
• Millet.
• Quinoa.
• Black rice.
• Brown rice.
• Red rice.
• Wild rice.
• Oatmeal.
• Popcorn.
• Whole-wheat flour.
• Whole-grain breakfast cereals.
• Whole-wheat bread, pasta or crackers.

Make sure to read the ingredients label for cereals and crackers. Don’t buy anything that has more than two ingredients you don’t recognize.

Fresh Vegetables

Fresh vegetables are also a good source of fiber. Sorry folks, but potato chips and french fries do not count as fresh vegetables! Once again eating fresh vegetables daily significantly lowers your risk of cardiovascular disease.

Bottom Line

Eating red meat and saturated fats does very little to increase your risk of heart disease, but it also does not reduce your risk. Raising livestock on factory farms causes significant harm to the environment and puts people at risk of infectious disease. Eating meat from locally raised animals is safer.

Eating high fiber foods, whole grains, nuts, fruits and vegetable does substantially reduce your risk of cardiovascular disease as well as cancer.

Eating highly processed foods, and this includes the new industrial fats made by interesterfication increases your risk of cardiovascular disease and cancer. The biggest risk of these is probably because they encourage people to eat more calories than they need and have almost certainly led to the epidemic of obesity.

The most concise recommendation for a healthy diet comes from author Michael Poulin: “Eat food (food is anything your grandmother would have recognized as food), mostly plants, not too much.”