Are dairy products healthy?

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Many books and articles contain health recommendations based on little or no scientific evidence. So when making personal decisions about how to maintain and improve one’s health, it is important to look for books and articles based on solid studies, especially large, well-controlled ones. A good example of science-based health information can be found in the July/August 2011 issue of the Nutrition Action Health Letter, published by the Center for Science in the Public Interest. It evaluates the pros and cons of consuming dairy products, Some of its key points:

Bones
We all know that milk is a major source of dietary calcium, which is needed to maintain bone density. Recently however, some health writers have contended that eating animal protein lowers bone density. Because protein contains amino acids, the alleged mechanism is increased acidity of the blood, prompting the body to respond by leaching calcium from the bones to neutralize the acid. Since milk is a protein source, it is implicated in bone loss. However, scientific study has refuted this contention. In actuality, bone mineral density is higher among people who eat more protein and lower among people who eat less protein. Radio isotope studies that tracked actual deposition and depletion of calcium have verified that consumption of dairy foods does not increase bone loss as we age.

Colon Cancer
A major analysis by the Harvard School of Public Health of 10 studies conducted in 5 countries, involving over 500,000 people concluded that people who drank at least one cup of milk per day had a 15% lower risk of colon cancer than those who drank less than 2 cups per week. Similarly, people treated for colon cancer who took 1200 mg of calcium per day and who had an above-average Vitamin D level had 15% less chance of recurrent colon cancer than those who didn’t take the calcium. Twenty-five percent of experimental animals fed a high-fat diet low in fiber, calcium, Vitamin D, and folic acid, developed colon tumors, but those supplemented with calcium and Vitamin D got none.

Prostate Cancer
There is some inconsistent evidence that high calcium consumption (in excess of 1500 mg/day) may increase the risk of prostate cancer. Milk increases the body’s level of insulin-like growth factor-1 (IGF-1), a hormone that stimulates the growth of both muscle and bone, but may also stimulate prostate-cancer growth. Even though a study of men receiving a 1200 mg calcium supplement daily showed no prostate cancer increase, the article recommended that men limit their calcium intake from food and supplements combined to 1000 mg/day if under 70 years of age and 1200 mg/day if over 70.

Blood Pressure
Adding 2 servings per day of low-fat dairy foods to a diet rich in fruits and vegetables, lowered blood pressure even further. In addition, a study of 28,000 women over 10 years showed that those consuming at least 2 cups/day of low-fat dairy foods reduced their risk of high blood pressure by 10%.

Weight Loss
When restricted to the same number of calories per day, women consuming more dairy products showed no difference in weight loss than those who consumed less dairy. However, when allowed to eat all they wanted at the end of the study, the dairy group consumed fewer calories. The implication is that dairy may help control appetite. While the weight-loss results were equivocal, the women in the low-dairy group lost bone density in their hips, while the high-dairy group did not. This is an important finding, considering that dangerous loss in bone density is common among both women and men as they age.

Lactose Intolerance
Lactose is the sugar found in milk. The following is the lactose content of some dairy products:

• 8 oz cup of milk: 12 grams
• 6 oz cup of yogurt - 10 grams
• 1 oz hard cheese or cream cheese - 1 gram or less
• ½ cup cottage cheese - 4-5 grams
• ½ cup ice cream - 4-5 grams

Many people think they are lactose-intolerant, However, the article cites evidence that between one-third and three-quarters of people who think they are lactose-intolerant are actually not so. Many of them show none of the typical symptoms of gas or diarrhea when lactose is put in their non-dairy drinks without their knowledge. Many people’s digestive systems can adjust to lactose by building up intestinal bacteria over a period of time. So the authors recommend that people who think they are lactose intolerant try to adjust to lactose by:

• Limiting lactose to 12 grams at a time (the amount in one 8 oz glass of milk).
• Consuming lactose along with other foods to give it more time to be digested
• Eating dairy foods regularly to maintain lactose-digesting bacteria
• Other Health Issues Related to Dairy Products

Diabetes
A study of 200,000 people over 20 years showed that those consuming 3-5 servings per day of dairy products had a 14% lower risk of Type II diabetes than those consuming less than 1.5 servings per day. However, it is not known whether that is an effect of the dairy products or another factor common to people who consume more dairy products.

Breast and Ovarian Cancer
Eight studies of 350,000 women in several countries did not find any link between milk consumption and breast cancer. However, research on 500,000 women in the U.S. and Europe did show a weak and marginally significant increased risk of ovarian cancer for women who consumed more than 30 grams of lactose per day. However, two major cancer research organizations did not feel the evidence was conclusive.

Bottom Line
Dairy products made from skim or one-percent milk can be considered health-promoting foods. They contain large quantities of calcium necessary for maintaining bone-density as we age. Also, most are excellent sources of protein (except products made primarily from milk fat, such as cream cheese and butter). Milk appears to help control blood pressure and avoid colon cancer, and may also help control appetite. However, high milk consumption may increase the risk of prostate cancer among men and ovarian cancer among women. Therefore, men should limit calcium consumption from food and supplements combined to 1000 mg/day below age 70 and 1200 mg/day above age 70. Adequate Vitamin D intake is essential for healthy bone mineralization, even if calcium intake is adequate. Many people are deficient in Vitamin D because of low sun exposure. Current recommendations for daily Vitamin D supplementation are in the neighborhood of 1,000-2,000 IU.

Additional Note
The main type of saturated fat found in milk (myristic acid) is particularly potent in raising blood cholesterol, specifically the harmful low-density variety (LDL). Because of that, consumption of milk fat should be very limited. High proportions of milk fat are found in cream, butter, ice cream, cheese (especially cream cheese and soft cheeses like Brie), whole milk, and 2% milk. That is why non-fat and 1% fat milk products are preferable. Unfortunately, many dishes popular in the U.S., such as cheese burgers cheese ravioli, macaroni and cheese, and pizza, contain large amounts of cheese. The evidence indicates that the cardiovascular health of Americans would benefit from a reduction in cheese consumption.

How to Avoid Inflammation of Your Arteries

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Inflammation of the blood vessels and other bodily tissue has become increasingly recognized as being complicit in heart disease, arthritis, and decline of mental capacity. Fortunately, the choices we make concerning what and how much we eat and drink, and how much exercise we do, can dramatically influence the degree of inflammation we experience. The information presented herein concerning lifestyle factors that affect inflammation, comes from a review article by O’Keefe, Gheewala, and O’Keefe in the Journal of the American College of Cardiology (vol. 51, no. 3, 2008).

Meals that are high in calories, and/or contain easily digestible, quickly absorbable, calorie-dense processed food and drink result in spikes in blood glucose and triglycerides (blood-borne fats), overwhelming the body’s ability to process them. Oxidative free radicals are then produced which attack the lining of the arteries (endothelium), inflaming them, causing them to constrict, and building up fatty deposits (atherosclerosis). In contrast, smaller meals containing ingredients that digest more slowly (e.g. fiber) produce smaller surges in blood sugar and triglycerides, and are thus not inflammatory.

Even a single meal high in saturated fat results in an increase of triglycerides, oxidative free radicals and inflammation, which negatively affects the function of the endothelium, causing constriction of the arteries, and raising systolic blood pressure.

A high glycemic meal is one that causes a spike in blood glucose. The Glycemic Index rates foods in comparison to glucose. Foods scoring closer to 100 cause relatively large spikes in blood sugar, while foods scoring closer to zero produce relatively small spikes. See a table listing the glycemic index of various foods from Harvard medical school. The body often responds to high glycemic index foods with insulin surges that remove sugar from the blood and can actually result in low blood sugar (hypoglycemia), an ebb in energy, and hunger. Regularly eating this way predisposes one to excess fat on and around the organs below the abdominal muscles (visceral fat) which, in turn, leads to inflammation and insulin resistance and raises the risks of diabetes, high blood pressure, and cardiovascular disease.

Dietary changes that reduce the magnitude of the triglyceride spike following meals by 20% and 40% respectively have been shown to reduce the risk of coronary artery disease by 30% and 40%. In addition to avoiding foods with a high glycemic index, adding certain foods to the diet can slow down digestion and reduce the spikes in glucose, insulin, and triglycerides. For example, nuts eaten along with a high-carbohydrate meal slow digestion and reduces blood sugar spikes by 30-50%. This both reduces oxidative stress, and provides antioxidants that combat such stress. In fact, a Mediterranean diet supplemented with either 30 grams of nuts or olive oil was found to reduce systolic blood pressure, blood sugar, and biomarkers of inflammation significantly better than a low-fat diet. Eating nuts 5 times per week was found to reduce risk of diabetes and cardiovascular disease by 20-50%. Quality protein sources low in saturated fat have a similar beneficial effect. These include egg-whites, lean meats, fish, casein, and whey protein, among others. Fish oil lowers triglyceride levels by 16-40%.

As expected, physical exercise has a positive effect, reducing post-meal spikes in blood sugar and triglycerides. Exercise is most beneficial in this regard if it is done within 2 hours before or after a large meal. Loss of body fat by diet control and/or exercise can also reduce post-meal spiking of blood sugar and triglycerides.

Alcohol consumption shows a J-shaped relationship with inflammation and blood sugar spiking, in addition to various other health problems such as coronary artery disease, diabetes, stroke, dementia, and all-cause death, with the lowest levels of these problems at 1-2 drinks per day for men and 0.5-1 drink a day for women. The J-shape means that drinking no alcohol increases the risk of these problems somewhat, while drinking in excess greatly increases the risks of these problems.

Characteristics of Inflammatory Meals

• High in calories
• High in calorically-dense foods
• High in saturated fat
• High in refined carbohydrates
• Contain foods with high glycemic index

Characteristics of Diets That are Not Inflammatory

• Smaller meals spread over the day
• Low in saturated fat
• Low in, or free of trans fats
• Low in processed carbohydrates
• Low in foods with high glycemic index
• High in unprocessed fruits and vegetables rich in antioxidants
• High in nuts, seeds, and whole grains
• Contain vinegar (1-2 tbsp eaten with a meal high in refined carbohydrates reduces the blood sugar spike by 25-35% and reduces hunger)
• Moderate amounts of lean animal protein
• Moderate amounts of beneficial fats such as fish oil and monounsaturated oils (e.g. olive,canola)

The following Foods High in Antioxidants Help Prevent Oxidative Damage to the Endothelium

• Berries
• Red wine
• Chocolate
• Tea
• Pomegranates
• Cinnamon (also reduces glucose spike caused by high-glycemic-index meal)

If you are concerned about the possibility of inflammation in your arteries, you can ask your doctor about testing the C-reactive protein level in your blood when you get a checkup. However, if your total cholesterol level is below 200 and your HDL level is above 55, it is very unlikely that you have a problem with arterial inflammation. If your C-reactive protein level is above 1.0 or the ratio of your total cholesterol level to your HDL level is above 4.0, you would likely benefit from following an anti-inflammatory diet and exercising regularly.

Fatty Liver Disease: Another Reason to Avoid Obesity

An article in the January 2011 issue of the Harvard Health Letter reveals that the epidemic of obesity has increased the occurrence of fatty liver disease. Previously, most cases of fatty liver disease were related to excess alcohol consumption, but now, many cases are related to excess body fat, which can lead to Type II diabetes. Fatty liver disease affects 70-90% of those who are obese and/or have diabetes.

Abdominal obesity can lead to metabolic syndrome (elevated blood pressure and levels of triglycerides and blood sugar, and low HDL (good cholesterol). Overfilled fat cells become resistant to insulin (which lowers blood sugar by storing it in the cells) resulting in excess fatty acids in the blood. Fat then accumulates in liver cells, which can lead to inflammation and liver tissue damage.  This can in turn bring about liver fibrosis (buildup of fibrous tissue) or cirrhosis (buildup of scar tissue). Cirrhosis increases the risk of liver cancer.

Fatty liver disease increases the risk of heart attack and stroke because a fatty liver produces inflammatory factors that can promote the deposition of plaque in the arteries, leading to arterial narrowing.

The only effective treatment for fatty liver disease is to lose weight.

Bottom Line
If you want to avoid or reverse fatty liver disease, avoid gaining unnecessary body fat or lose existing excess body fat through a program of good nutrition and exercise. Both caloric restriction and exercise are essential parts of any weight-loss program.

As We Age, Cholesterol Level Loses Its Value as a Risk Factor

Because both a high total cholesterol level and a high LDL-cholesterol level are risk factors for heart disease, statin drugs, which lower both levels, are widely prescribed. In the U.S., more prescriptions are written for Lipitor, the most popular statin, than for any other drug. Estimates for the number of people who take statins range between 11 million and 30 million. But should so many people be taking statins? A recent analysis, in which scientists reviewed 14 studies that included data from over 34,000 patients, showed little evidence that statins prevent heart trouble in patients with no history of cardiovascular disease. And because there is some evidence linking low cholesterol levels with increased risk of death from other causes, the study authors feel that doctors should be more cautious about prescribing statins.

An important factor to consider when deciding whether or not to prescribe statins is the patient’s age. A study by Kronmal et al., entitled, “Total Serum Cholesterol levels and mortality risk as a function of age” in the Archives of Internal Medicine (vol. 153, pp. 1065-1073, 1993) examined how age affected the ability of cholesterol level to predict the risk of dying, and it showed that the predictive value declined with age.
The most important consideration when judging mortality risk is the overall likelihood of dying from any cause. In that regard, at age 40, those people with higher total serum cholesterol levels had a significantly higher all-cause mortality risk. However, the relationship declined with age, and by age 60, the relationship between total cholesterol level and all-cause mortality had vanished. By age 80, the relationship actually reversed, so that those with higher cholesterol levels were at significantly lower risk of dying.

Looking specifically at the risk of death from coronary heart disease, the death risk at ages 40, 50, and 60 years was greater for those with higher cholesterol levels, although the effect got smaller with age. By age 70, the relationship was still positive but weak, but by age 80 the relationship reversed, and those with higher cholesterol levels actually had less chance of dying.

Looking at death due to causes other than heart disease, (e.g. cancer), from age 50 on, there was a lower risk of dying as cholesterol levels rose. This apparent protective effect of cholesterol against non-heart-disease death increased with age. Seventy-three percent of 80 year-old men with cholesterol levels above 240 survived for 5 years, while only 49% of those with levels below 240 did. The effect was in the same direction but weaker for women, with a 74% and 70% 5-year survival rates for women with cholesterol levels respectively above and below 240 mg/dl. In regard to cancer alone, higher cholesterol level was associated with lower death risk.

Bottom Line
The current practice of the medical establishment of prescribing statins to anyone with a total cholesterol level above 200 appears to be unjustified. For patients with elevated cholesterol levels and a history of heart disease, statins provide a proven reduction in risk. However, for patients with mildly elevated levels and no history or heart disease, the evidence in favor of prescribing statins is weak or nonexistent. And for men above age 70, even those with cholesterol levels above 240, statins could very well increase the risk of death.