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3/11/2019

Low levels of HDL (the “good” cholesterol) appear connected to many health risks, not just heart disease

Burning more calories each day than you consume may have been the diet advice from the past, but that doesn’t work for everyone.  Instead, the focus should be on eating whole foods and avoiding processed carbohydrates — like crackers, cookies, or white bread. A recent review in JAMA Internal Medicine further casts a light on the shaky history of nutritional science. Before the 1980s, regulations did not require researchers and physicians to declare conflicts of interest before publishing a paper. By not announcing affiliation, research had the potential to be swayed by money and funding. That’s why it had to change.
Are fat and cholesterol the dietary “bad guys”?

A study funded by the Sugar Research Foundation (SRF) from the 1960s found that cholesterol and fat were the main contributors to weight gain and responsible for an increased risk for coronary heart disease. These results kick-started the country’s decades-long consumption of added sugar. With fat removed, food lost taste and appeal, so manufacturers added sugar to combat this. The country’s intake of sugar and processed carbohydrates went up, while our intake of fat went down. Dr. David Ludwig, a professor in the Department of Nutrition at the Harvard T.H. Chan School of Public Health, says “Overall, these processed carbohydrates are worse than the fats they replaced.”

The JAMA review from September found that the doctors involved with the study were in fact paid by the SRF. Their research was tainted due to conflict of interest. The SRF — and thus the doctors paid by the SRF — directly benefited from the results of this 1960s study, and they profited tremendously from the uptick in sugar sales, while consumers made health decisions on the basis of questionable information.
The scoop on carbohydrates

It is true that fat has more calories than carbohydrates, including sugar. But by that logic, a sugary beverage is better for you than a handful of nuts. That’s just not what the unbiased studies have shown. Looking only at calories ignores the metabolic effects of each calorie; the source of the calorie changes how you digest it and how you retrieve energy from it.

Carbohydrates have been categorized as simple or complex in the past. Dr. Ludwig says these classifications are misleading. Many doctors are pulling away from those narrow categories and moving toward the all-encompassing terms of high glycemic index and low glycemic index. An apple is a simple carbohydrate because it is digested quickly by the body, but fruit is better for you than other simple carbohydrates like chips or crackers. That’s why Dr. Ludwig views the glycemic index as a more accurate measure of a food’s value (good or bad). When something has a low glycemic index, it raises your blood sugar levels slowly, increasing your insulin levels gradually.

That’s good, because too many insulin spikes result in insulin resistance, where your body stops responding to insulin it is producing (also known as type 2 diabetes). High-glycemic foods, on the other hand, cause blood sugar levels and thus insulin to rise quickly, prompting the overproduction of insulin and fat storage. Ludwig would rather you focus on low-glycemic foods like whole-grain pasta, wheat bread, fruits, beans, and nuts. High-glycemic foods include candy, croissants, and scones. By choosing the low-glycemic foods and thus the minimally processed foods, people can lose more weight, feel fuller longer, and remain healthier.
Can you make peace with fat?

Today you can look at food differently. Counting calories alone doesn’t work because ultimately it matters where those calories come from; this matters more than the number of calories ingested. Dr. Ludwig says, “It was this calorie-focus that got us into trouble with the low-fat diet in the first place.”

So don’t be afraid to go back to fat. Just make sure it’s the healthy fats like avocado, olive oil, and nuts. Don’t cut out the fat, and don’t make a habit of eating products labeled “fat free.” It’s a relatively recent development. Whether at work, working out, watching a movie, or just about anything else, it’s as if there’s been an epidemic of dehydration that can only be warded off by constant access to water. It seems strange to me; almost no one did this a decade or two ago. Were people in the past less healthy or did they feel less well because they drank when they were thirsty or with meals, rather than throughout the day?
Water is important

Clearly, water is a necessity. Without it, a person can only survive a few days. Water serves a number of vital functions, including:

    keeping organs and tissues healthy (since every cell requires water)
    helping deliver oxygen and nutrients throughout the body
    “flushing” the kidneys and bladder which help keep them healthy
    maintaining a healthy digestion
    keeping the blood pressure and heart rate in an ideal range
    helping keep body temperature normal.

Given that the human body relies so heavily on water, it should not be surprising that our bodies have evolved to conserve and regulate it. We have intricate systems that connect the brain, the kidneys, and other parts of the body to keep our fluid status as close to ideal as possible.

For example, when fluid levels are low, the hypothalamus (in the center of the brain) sends out a signal to the nearby pituitary gland telling it to release a hormone (called ADH) that will make the kidneys hold on to water and produce more concentrated (and darker) urine. Meanwhile, the brain’s thirst center is activated and that leads people to head for the faucet. The opposite occurs when fluid levels swing toward “too much” — less ADH is released and the kidney sends more water to the bladder to be urinated away. In most people, these systems perform well to keep things running smoothly.
When things go awry

When you go for a jog on a hot, humid day or when you’re sick with a fever or diarrhea, you can lose a lot of fluid in a short time without realizing it. Young children (who cannot ask for water) or the elderly (whose kidneys and thirst centers may not function normally) may be particularly susceptible to dehydration. These are situations in which paying particular attention to water intake makes a lot of sense.
So why all the water bottles?

Outside of situations in which water levels could get dangerously out of whack, it’s usually enough to rely on thirst and a normal diet to keep your water levels where they should be.

For many, sipping water all day becomes more about habit than physiology or health. Some people try to drink a lot because they’ve been told it “dilutes out toxins” or will help them lose weight. Others monitor the color of their urine and drink enough water to keep it lighter in color.  Whether this much attention to water intake is really necessary or helpful is uncertain.
Water in the news

Research regarding how we ingest water has shed new light on the health impact of how we hydrate. For example:

    Studies have linked cola consumption with low bone density (a precursor of osteoporosis).
    Colas are highly acidic and may contribute to erosion of tooth enamel.
    Tap water (with or without home carbonation) contains fluoride that bottled water does not. That’s important because fluoride has a big impact on the prevention of cavities and is considered vital in maintaining oral health; most bottled water doesn’t contain fluoride.
    A recent study found support for the idea that drinking more water may help you maintain a healthy weight: among more than 18,000 people surveyed those who drank more plain water tended to consume significantly fewer calories.

It’s worth mentioning that there is such a thing as too much water. “Water poisoning” is not common but can be a serious problem for people with psychiatric disease, those taking certain medications or who have abnormally high levels of ADH, or others who intentionally drink excessive amounts of water. The danger comes from a low sodium level in the blood and brain swelling which may develop when the body has too much water.
What about club soda and tonic water?

Club soda and tonic water deserve special mention. Club soda has added minerals (such as sodium or potassium) for flavor; for some, the added sodium might contribute to higher blood pressure and fluid retention. Tonic water contains quinine, which gives it a slightly bitter taste (that seems to go well with gin); it contains about 120 calories per serving. The quinine can be a problem for people with heart rhythm disorders (although quinine has also been touted as a treatment for muscle cramps).
And is it true we should all drink at least eight glasses of water each day?

No one is sure where the recommendation to drink eight glasses of water per day comes from. The most plausible explanation I’ve heard is that it comes from the military. Because a day’s worth of water is heavy and difficult for a soldier to carry around, it was important to know just how much is needed; the estimate was approximately eight glasses of water/day. But keep in mind this estimate applied to active soldiers carrying heavy packs; and it included water contained in food (which can be a big contributor; carrots and broccoli are nearly 90% water).  So, the average person can drink far less than eight glasses of water per day without a problem.
And in conclusion…

Carrying water around 24 hours a day is almost certainly unnecessary. Most of us will get plenty of water if we drink when thirsty and consider the water in our foods toward the daily fluid intake. If you like to drink small amounts of water throughout the day, it’s unlikely to cause harm. But it may be a waste of money and effort; and a predictable side effect is frequent urination. After all, if you drink more than you need, your kidneys will do exactly what they’re supposed to do: get rid of the excess fluid.

Ask your doctor if there is any reason you should pay particular attention to your water intake; those taking certain medications (such as ibuprofen or related drugs) or those with certain conditions (such as kidney stones) may be advised to drink more. But for the rest of us, it may be just as well to leave your water bottle at home. Most everyone these days is aware that a high level of cholesterol is a risk factor for heart disease. For years, the thinking has been that there is “bad” cholesterol (LDL cholesterol) and “good” cholesterol (HDL cholesterol). Studies of populations (epidemiological research) have clearly demonstrated a strong association between low levels of LDL cholesterol and a lower risk of developing heart disease. LDL cholesterol reduction with drugs such as statins has been demonstrated to reduce cardiovascular risk. Thus, both the epidemiology and the randomized clinical trials support LDL cholesterol’s role as a risk factor for heart disease —  and that by lowering LDL we can lower the chances of heart attack and stroke.

With respect to HDL cholesterol, the epidemiology supports an association between high levels of HDL cholesterol and lower cardiovascular risk. However, unlike the LDL cholesterol story, recent clinical trials of drugs that specifically raise HDL cholesterol have not been shown to improve cardiovascular outcomes. Why is there this disconnect? That has been a pressing question among cardiovascular researchers.

A paper that was just published in the Journal of the American College of Cardiology sheds some light on the answer. In total, 631,762 people were studied. The authors found that low HDL cholesterol levels were associated with a number of factors that affect health, including low incomes, unhealthy lifestyles, higher triglycerides levels, other cardiac risk factors, and medical problems. Thus, the association between low HDL cholesterol and worse cardiovascular outcomes could be due to these other factors and not the low HDL cholesterol itself.

This study found that lower HDL cholesterol levels were associated with a higher risk of death from cardiovascular causes, as prior studies have shown. However, there was also a higher risk of death from cancer and other causes compared with those having average levels of HDL cholesterol. That finding makes it seem as though low HDL cholesterol isn’t just predicting cardiovascular death — which might make sense if it is really causing heart disease — but it is also predicting cancer deaths and other causes of death. And there is not a good biological explanation for why a low HDL cholesterol level should do that. The conclusion the authors reach is that low HDL cholesterol isn’t really causing any of these problems such as heart disease or cancer, but rather the underlying cause of the low HDL cholesterol, such as an unhealthy lifestyle, is the real driver of worse outcomes.

What does all this mean practically? Well, first of all, more research on the relationship between low HDL cholesterol and heart disease is still needed. There are some large clinical trials of HDL cholesterol raising drugs that are ongoing, so these studies may provide even greater insight into whether raising low HDL cholesterol protects cardiovascular health. In the meantime, it probably means that it is unlikely to be useful to take medications solely for the purpose of raising low HDL cholesterol levels. And if you have a low HDL cholesterol level, this study reinforces that exercise and a heart healthy diet are the way to go and might decrease some of the health risks seen in people with low HDL cholesterol levels.

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