Saturday, March 12, 2005

Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating by Walter Willett MD 2001

This is a book by the Harvard epidemologist who has looked at the various longtidudinal studies of health and diet to glean some factual assessments. Very fact based without the hype, helping you to make your own decisions.

First a blurb on the book: from's Best of 2001
Aimed at nothing less than totally restructuring the diets of Americans, Eat, Drink, and Be Healthy may well accomplish its goal. Dr. Walter C. Willett gets off to a roaring start by totally dismantling one of the largest icons in health today: the USDA Food Pyramid that we all learn in elementary school. He blames many of the pyramid's recommendations--6 to 11 servings of carbohydrates, all fats used sparingly--for much of the current wave of obesity. At first this may read differently than any diet book, but Willett also makes a crucial, rarely mentioned point about this icon: "The thing to keep in mind about the USDA Pyramid is that it comes from the Department of Agriculture, the agency responsible for promoting American agriculture, not from the agencies established to monitor and protect our health." It's no wonder that dairy products and American-grown grains such as wheat and corn figure so prominently in the USDA's recommendations. Willett's own simple pyramid has several benefits over the traditional format. His information is up-to-date, and you won't find recommendations that come from special-interest groups. His ideas are nothing radical--if we eat more vegetables and complex carbohydrates (no, potatoes are not complex), emphasize healthy fats, and enjoy small amounts of a tremendous variety of food, we will be healthier. You'll find some surprises as well, such as doubts about the overall benefits of soy (unless you're willing to eat a pound and a half of tofu a day), and that nuts, with their "good" fat content, are a terrific snack. Relying on research rather than anecdotes, this is a solidly written nutritional guide that will show you the real story behind how food is digested, from the glycemic index for carbs to the wisdom of adding a multivitamin to your diet. Willett combines research with matter-of-fact language and a no-nonsense tone that turns academic studies into easily understandable suggestions for living.

I will highlight key points and thought provoking items. As usual my comments are in bold italics.

Chapter 3 Healthy Weight

Prior Body Mass Index (BMI) studies have proven that disease incidence starts to grow exponentially (especially for type 2 diabetes) from a BMI of 21. Implying the optimal BMI was around 21. These first studies neglected to adjust for the fact that smokers tend to be underweight due to appetite suppression from smoking, and terminally ill patients tend to die underweight due to chronic wasting. Adjusting out smokers and terminally ill, leads to a more sobering graph that shows that disease incidence continues to the decline to a BMI of 17. This means that the skinnier you are the better. This is also consistent with the only proven longevity increasing strategy – caloric restriction. The fewer calories you eat, the skinnier you become and stay – and the fewer diseases you are susceptible to contract, leading to the longest possible life.

“Our taste for sweet things, for example, helped early humans sort through leaves to find the tender young ones with a ready supply of energy”. Interesting speculation.

Chapter 4 Surprising News about Fat
“Saturated fats come in gradations of bad. The staturated fats in butter and other dairy products most strongly increase LDL (bad) cholesterol. Those in beef aren’t quite as powerful at boosting LDL, and those in chocolate and cocoa butter have an even smaller impact.” Bad news for fans of dairy, but good news for chocolate lovers.

Monosaturated fats are oils (at room temperature). Olive, peanut, and canola oils as well as avocados and most nuts are excellent sources. Eat these liberally.

Polyunsaturated fats are also oils, but unlike saturated and monosaturated your body cannot synthesize these itself; therefore you must ingest these. These are called essential fats because of this fact. Omega 3 and Omega 6 fats are polyunsaturated that you hear a lot about. Good sources include corn and soybean oil, seeds, whole grains, and fatty fish.

Transfats are man made, and are created from polyunsaturated fats. They are very bad for you. Details will come later.

“With regard to heart disease, the most important lipoproteins are high-density (HDL) and low-density (LDL) and very low-density, which is composed of triglycerides… When your bloodstream carries too many LDL particles, they can end up in wrong places, especially inside cells that line the blood vessels. Once there, LDL is attacked by highly reactive free radicals and transformed into oxidized LDL. Oxidized LDL can damage the artery lining and can also kick off a a cascade of reactions that clog the artery and set the scene for artery blocking blood clots. “

“HDL particles sponge up excess cholestor from the lining of blood vessels and elsewhere and carry it off to the liver for disposal.”

“Triglyceride makes up most of the fat you eat, and most of the fat that circulates in your bloodstream.”

“Replacing 5% percent of total calories at saturated fat with unsaturated (either poly or mono but not trans!) would reduce the risk of heart attack or death from heart disease by about 40%.”

“Replacing just 2% of total calories from trans fat with the same number of calories from unsaturated fats would cut the risk by 50%.”

In 1988 a study was conducted of the ‘Mediterranean diet’ (a diet low in saturated and trans fats, but high in unsaturated fats, especially omega 3 fats). Just 2.5 years into the study, it was ethically stopped early because the results were so compelling – a 70% reduction in deaths of all causes.

Another “study from Holland showed that calories from trans fats not only raised LDL as much as from saturated fats, but also trans fats substantially lowered HDL.” This is why trans fats are so bad! Trans fats also make blood platlets stickier, causing more clotting (which can lead to strokes and heart attacks).

“Women who ate the most trans fats (about 3% of total calories) were 50% more likely to develop heart disease than those who ate the least (about 1% of total calories)… Women with the lowest intake of trans fats and the highest intake of polyunsaturated fats were 70% less likely to develop heart disease when compared with women who ate the most trans fats and the least polyunsaturated fats.”

Omega 3s were originally found to be beneficial because of the study of the low heart disease rates for Eskimos who have a very high fat diet, but most of those fats are omega 3. Since then, dozens of subsequent studies have shown that omega 3 from fish and other sources help prevent heart attack, stroke by improving the balance of cholesterol and limiting inflammation.

“The clearest and most consistent finding from both animal and human studies is that too many calories, regardless of food source, are far more important to the development of breast cancer than dietary fat... cutting daily calories by 30% can drop cancer rates by 80%.”

“Too many calories in relation to exercise levels is the strongest dietary link with colon cancer (fiber and fat are not culprits).”

More evidence for caloric restriction. It is not what you eat, but more important how much (or more accurately how little) you eat.

“Unsaturated fats that decrease the risk of heart disease would not increase the risk of prostate cancer”. Good news, so you can eat those unsaturated fats with impunity upto your daily caloric limit.

“Chicken fat is much higher in polyunsaturated fat than beef, probably the main reason why substituting chicken for red meat is related to a lower risk of heart disease.”

“Eat one or more good sources of omega 3 every day – fish, walnuts, canola, flaxseed are the best sources.”

Chapter 5 Carbohydrates for Better and Worse

Four things contribute to insulin resistance (type 2 diabetes)
1. Obesity. A BMI over 21 starts to dramatically increase your risks.
2. Inactivity. Regularly exercised muscle cells handle insulin and glucose very efficiently. Further the less active you are the fewer muscle cells you have.
3. Dietary Fat. Low intake of poly and mono saturated fats coupled with a high intake of trans fat leads to greater resistance.
4. Genes. Your heritage can play a factor in which case being vigilant on your weight, exercise, and fat intake becomes doubly important.

Studies show the following about fiber and whole grain carbs:

That as little as 7.5 grams of fiber per day compared to a daily intake of 2.5 grams, leads to a 30% reduction in the incidence of type 2 diabetes.

2.5 servings of whole grains per day vs. 1 serving per week lead to a 30% reduction in heart disease for women.

Harvard estimates that eating 1 bowl of high fiber cereal (5 grams) cuts the chance of heart disease by 33%.

Fiber intake doesn’t affect rates of colon cancer. This is a shocker.

My theory on fiber is the following. First fiber is indigestible so it fills you up without costing you any calories, thus reducing your caloric intake. Second, fiber speeds up your digestion and prevents the full absorption of other substances (like certain fats and cholesterol), thus removing additional calories from your intake. Could it be just another form of caloric restriction?

Chapter 6 Choose Healthier Sources of Protein

“Studies have shown a consistent 30 to 50% reduction in heart disease associated with eating nuts several times a week”

“Women who ate the most protein, about 25% of daily calories, were 25% less likely to have had a heart attack or to have died of heart disease than the women who eat the least protein, about 15% of calories.”

But is it safe to eat a lot of protein? Yes, “The amount of protein doesn’t seem to have an effect on the development of type 2 diabetes”. And no, “Women who ate more than 95 grams of protein a day had more broken wrists than those eating an average amount of protein, less than 68 grams a day.” “Extra calcium is needed to neutralize protein related acids. This calcium is mostly pulled from bone.” So too much protein could be dangerous to your bones!

The sad truth about soy protein. Only one major study has proven the benefits of soy protein. Wait’ll you digest the facts and implications before deciding if soy is truly beneficial. “In a 1995 article in the New England Journal of Medicene, a satistical analysis of the results of 38 studies showed that eating 50 (!) grams of soy protein per day (!) in place of animal protein reduced total cholesterol by 9.3% and LDL cholesterol by 12.9%.” Lets take a moment to analyze this. 50 grams of soy equates to 1.5lbs of Tofu or 64 ounces of Soy milk (a whole ½ gallon and it also equates to about 1200 calories.) So given the incredibly large intake of soy, perhaps the reduction of in cholesterol has more to do with the fact that you didn’t eat the animal protein (and animals fats), and less to do with the beneficial nature of soy. The soy just filled you up and prevented you from eating something more harmful. Unfortunately for soy, things get worse. Soy contains phytoestrogens (plant horomones). “Breast tissue removed from women taking soy supplement showed substantial more cell growth and division than the tissue removed from women not taking soy. Animal studies also suggest reason for caution because soy estrogens promote the multiplication of breast cells…” “It’s not wise to go overboard eating soy products.” Couldn’t have said it better.

Chapter 7 Eat Plenty of Fruits and Vegetables

“It appears that fruits and vegetables probably don’t have a blanket anticancer effect. Instead certain classes of fruits and vegetables seem to work against specific cancers.”

35 servings per week (5 per day) were 15% less likely to have a heart attack than those who ate the fewest servings.

30 servings per week lead to a 30% reduction in stroke. Harvard calculates that each daily serving lowers your stroke risk by 6%.

Eating fruits and vegetables also lowers your cholesterol level, although no one knows exactly how. However, the obvious sometimes needs to be stated:
“Since eating more plant foods often means eating less meat and dairy products, lower cholesterol levels may come from eating less saturated fat.” It is not necessarily that fruits and vegetables are good for you. These foods are not as calorie dense as animal foods. If you get full on fruits and vegetables you may live longer since you just didn’t have the room to eat the foods that are really bad for you. This is in alignment with caloric restriction.

“How fruits and vegetables protect the human system from cancer, heart disease, GI problems, or age-related diseases is still something of a mystery.” We have found certain compounds within certain bodily tissues, and we have found those same compounds within certain plants. So far it is speculation that the plants are truly providing the compounds in proper dosage, frequency and potency to have any effect on our biology. It seems to make sense, but studies have not proven that eating more of a particular substance derived from a plant leads to less disease. It seems that the plants have many chemicals that are involved, and isolation leaves something critical behind.

“Those who consumed the most fiber, no matter what the sources, did not have lower risks of colon cancer or colon polyps.” Surprising!

Eat a lot and eat a variety of fruits and vegetables is the key take away.

Chapter 8 You are what you drink

“You may heard that you need to drink 8 eight ounce glasses of water a day in addition to whatever beverages you drink. That’s actually a medical urban legend. It probably comes from the fact that someone who eats 2000 calories of food a day needs about 64 ounces of fluid (to process the energy in those calories).” Most of this water is actually contained within the food you eat itself. Think how much of a glass of milk or piece of fruit or even a piece of meat is actually made of water.

8 oz of grapefruit juice a day appeared to increase the chances of developing kidney stones by 44%.

Coffee and tea drinkers were less likely to experience the following:

To develop kidney stones than non-coffee drinkers. Speculation centers on caffiene which is a diuretic; helping to flush out more water, making it too dilute for kidney stones to precipitate out.

To develop gallstones. Caffiene interferes with cholesterol crystallization, and promotes gall bladder contractions.

To experience suicide. California HMO studies show an almost 50% reduction in suicide rates.

For women, even 2 alcoholic drinks per day can raise her risk for breast cancer by 20 to 25%.

Chapter 9 Calcium: No Emergency

“There’s no solid evidence that merely increasing the amount of milk in your diet will protect you from breaking a hip or wrist or crushing a backbone in later years.”

“For men, a high calcium intake seems to increase the odds of developing prostate cancer, while for women, drinking a lot of milk has been linked with higher rates of ovarian cancer.” Studies have shown that “men who drank 2 or more glasses of milk a day were almost twice as likely to develop advanced or metastatic prostate cancer as those who didn’t drink milk at all”. “More careful analyses, suggest that calcium might be the culprit. Men who took in more than 2000 mg of calcium a day from food and supplements combined were almost three times as likely to develop advanced prostate cancer than men who got less than 500 mg/day.” Point of reference a single glass (8 oz) of milk contains about 350 mg of calcium.

“Breaking a hip in old age can be disabling, even deadly – almost ¼ of older people who break a hip die in the following year.”

“Vitamin D deficiency was much more common among women who had broken a hip than among women who had not.”

“Curiously, countries with the highest average calcium intake tend to have higher (!), not lower hip fracture rates.”

“As your body digests protein, it releases acids into the bloodstream. Calcium drawn mostly from the skeleton, helps neutralize these acids… when it comes to leaching calcium from bone, animal protein is somewhat more powerful than vegetable protein.”
Studies have “found that women who ate the most protein each day were more likely to break a wrist than women who ate the least. The same held true for women who ate red meat more than 5 times a week compared to with those who ate red meat less than once a week.”

Chapter 10 Take Multivitamin for Insurance

“Unfortunately, randomized trials in which volunteers have taken specific antioxidants have not shown much reduction in risk of developing cancer, cardiovascular disease or diabetes.” However, fruits and vegetables have proven such reductions. “This seeming contradiction may mean that you need the whole, complex net of antioxidants (and other chemicals) delivered by fruits and vegetables.”

“Getting plenty of folic acid seems to decrease the risk of developing colon cancer and breast cancer.” “Alcohol blocks the absorption of folic acid, and also inactivates circulation folic acid.” If you drink think about taking extra folic acid – approximately 600 mg/day to decrease the risks of cancer.

“During winter months, the amount of ultraviolet light hitting northern regions above 40 degrees latitude (eg. San Francisco, Denver, Wash DC) is not enough to generate vitamin D.” “A recent study showed that more than half of the people admitted to Mass Gen Hospital were vitamin D deficient.”

“Women who don’t get much vitamin K are twice as likely to break a hip as women who get plenty.” “We estimated that eating a serving of lettuce or other green leafy vegetables a day cut the risk of hip fracture in half when compared with eating one serving per week.” “…A fair number of Americans, particulary young ones, aren’t getting the vitamin K that they need, mainly because they don’t eat enough green leafy vegetables.”

“The 6 vitamins that many people don’t get enough of from their diets are:
Folic Acid
Vitamin B6
Vitamin B12
Vitamin D
Vitamin E
Vitamin K”

A simple multivitamin will fill in any gaps you have.

Chapter 11 Summary

“The healthiest nutritional strategy, summarized in this book includes:
Maintaining a stable, healthy weight under BMI of 25, ideally 21 to 23 or less.
Replacing saturated and trans fats with unsaturated fats
Substituting whole-grains with high fiber for refined grains and limiting sugar
Trading red meat for nuts, beans, chicken, and fish
Eating plent of fruits and vegetables
Using alcohol in moderation
Taking a daily multi-vitamin”

Nothing to it really.


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