Our most recent book has answers to the 200 most common questions that readers have asked us over the 19 years since this site began. Get it here: Your Diabetes Questions Answered
Phosphates Added to Many Foods Damage Your Kidneys and Cardiovascular System
Among the many risk factors for heart disease and kidney disease is something you never hear about from your doctor or the medical press: high levels of inorganic phosphates in the blood. This is partly because there are no profitable drugs available to combat high phosphate levels and partly because the big guns of the food industry, who are make huge contributions to the American Diabetes Association and the American Heart Association are who are putting these damaging phosphates into consumers' blood stream.
What Are Inorganic Phosphates?
Phosphates are compounds that contain phosphorous and oxygen. They are essential to the construction of every cell in our body as phosphates make up the backbone of DNA, They form essential components in cell membranes and are essential to the proper growth of plants. Adenoside Triphosphate (ATP) is the molecule every cell uses used to store energy. Without it, we're dead meat.
Therefore we get a dose of phosphates any time we eat any meat or vegetable. These are "organic phosphates" which are deeply bound into the structure of the foods we eat--so much so that only 40-60% of the phosphate we consume is actually bioavailable. The rest goes through us undigested.
But these organic are not the phosphates that pose a threat to health. The problem phosphates are the "inorganic phosphates"--chunks of phosphate containing rock--that are added to our foods. The are commonly used as preservatives, flavor additives, and to keep cream from separating in dairy products. Phosphoric acid, which converts to phosphate in our bodies, is added to soda to keep brown sodas from turning jet black, which would make them unappealing to most people. Phosphates are also frequently used to provide the chalky white pill material that holds the supplements you buy in pill form.
Unlike the organic phosphates found naturally in foods, these inorganic phosphates are 100% bioavailable. That means if you eat 500 mg of calcium phosphate, disodium phosphate, or any of the many other inorganic phosphates added to processed foods or supplements, the whole 500 mg will be absorbed. When it is, it will go into your bloodstream where where will raise your serum phosphate level.
It has long been known that consuming inorganic phosphates can be very dangerous for people with severe kidney disease, as failing kidneys can't remove them from the blood, and these phosphates precipitate out in the kidney, destroying what little function is left. But while doctors may be aware of this, few of them know that consuming inorganic phosphates also poses a major risk to normal people, because it can promote heart disease.
Inorganic Phosphate Consumption Is Linked to Heart Disease
We know from several well-conducted studies that there is a direct link between your serum phosphate level and the development heart disease. As a this review article explains,
Higher serum phosphate levels were independently associated with coronary artery calcification, vascular stiffness, left ventricular hypertrophy, and carotid artery disease, even among individuals with normal kidney function and serum phosphate levels within the normal range.
A study that matched CAC scans to serum phosphate levels verified that rising serum phosphate levels correlated directly to rising Agaston scores in a population who had completely normal kidney function.
The most comprehensive study to investigate the impact of phosphates on heart disease was a study of the Framingham Offspring. It looked at serum phosphate levels in a group of over 3,000 normal people and then looked to see which of them had developed heart disease sixteen years later. It found that:
... a higher level of serum phosphorus was associated with an increased CVD [cardiovascular disease] risk in a continuous fashion. ... Individuals in the highest serum phosphorus quartile experienced a multivariable-adjusted 1.55-fold CVD risk ... compared with those in the lowest quartile... Serum calcium was not related to CVD risk.
What this means is that the more inorganic phosphate circulating in your blood stream, the more likely you are to develop the hardening of the arteries that leads to heart attack and stroke.
Does Eating Inorganic Phosphates Raise Serum Phosphate Levels?
When I first read this study, I could not help but wonder if the high serum phosphate levels that caused heart disease were caused by eating diets high in inorganic phosphate or whether people destined to get heart disease might already have developed high serum phosphate levels as a side effect of an undiagnosed preexisting health issue. Could eating a diet high in added phosphates be all it took to raise serum phosphate levels?
This question was elegantly answered by a study published way back in 1977. Unfortunately, this article, which was available in full a few years ago is now hidden behind a pay wall.
In this study, healthy young subjects were allowed to eat only the foods supplied by the researchers. For four weeks they fed a control diet that contained no phosphate additives at all. Then, for the next four weeks, the subjects were fed a diet that contained the identical amount of calories, protein, fat, and carbohydrate as the control diet, but this diet was made up of foods containing inorganic phosphate additives, like American cheese, soda, and processed meats. The study explains, "The average phosphorus content of the daily menu was 979 mg during the control period and 2124 mg during the test period."
After a month of eating the foods with the added phosphates, the study participants blood was tested and it was found that they had experienced a dramatic rise in serum phosphates, accompanied by a decrease in serum calcium. The addition of the phosphates to their diets also caused digestive distress in many of the participants--in some cases it persisted throughout the whole study.
When the subjects' serum phosphate levels were measured, they were found to have "increased from 3.76 ±0.38 mg/100 ml during the control period to 4.43 ±0.30 mg/ 100 ml [mg/dl] during the high-phosphorus period."
This was an 18% rise in serum phosphate level. So yes, upping dietary consumption of inorganic phosphates will raise serum phosphate a lot, even in completely normal people.
And it is also worth noting that the amount of phosphate being consumed by the subjects in this study is far less than that what is consumed by the average person today since they were being fed a controlled diet containing only 2,200 calories. Higher caloric intakes would result in higher intakes of inorganic phosphates and higher serum phosphate levels, too.
These Added Phosphates Pose A Special Risk to People Eating Low Carb Diets
One reason is because people eating low carb diets, or for that matter, people with an interest in health are more likely than the average person to be taking supplements. But many chalky pill substrates used in supplements are made mostly of dicalcium phosphate.
Even worse, added phosphates may make what would otherwise be a very healthy low carb diet unhealthy, because these phosphates are added to many of the meats and almost all the poultry you buy in the supermarket, often without any labeling beyond a note that a "solution" has been added to the product.
Added phosphates are found in many processed and restaurant foods. They are added in the form of phosphoric acid to brown-colored sodas like Coke and Pepsi, including the diet versions, and are often found in bottled ice tea.
You will also find phosphates in most cold cuts, processed cheeses, and all rotisserie meats, including the ones sold as "all natural." There is phosphate added to half and half. They may even be found in supplements.
Phosphates are found in many of the meats you buy from the Meat department at your supermarket. Whole and parted out turkeys and many chickens have labels that tell you they have been "enhanced" with solutions supposedly added to improve flavor. These solutions almost always contain sodium phosphate. (You can see a discussion of these enhanced meats HERE.) Phosphates are likely to be in prepackaged hamburger, but they may also be in pork products that were cut by the butcher. The only way to find out is to ask the butcher if the pork was enhanced with a solution.
While food labels may list phosphates in the list of ingredients there is no requirement that manufacturers list them, so phosphates are often omitted from labels. (Details HERE) Even worse, even when phosphate appear on a label, you have no idea how much phosphorus has been added. So unlike the situation with sodium, you can't track your phosphorus intake and keep it to a safe level.
What is the Safe Level for Phosphate Intake?
Though people with kidney disease are told to keep their phosphorus levels between 800 to 1,000 mg/day, doing this is virtually impossible since it is unknown how much phosphorus there is in the many prepared foods they eat as the amount of added phosphorus never appears on the label. People with kidney disease do get blood phosphorus levels are measured, so they have some hint as to how they are doing.
But phosphorus levels are not tested as part of the standard suite of blood tests given to people with diabetes, so we have no way of knowing how high our blood phosphorus levels might be if we are eating processed and packaged foods.
When you eat out, you are almost guaranteed to be eating phosphates. Assume it is in all the chicken and turkey you order, whether it be roasted rotisserie chickens or the chicken loaf products used by many chain restaurants.
But these added inorganic phosphates aren't just in the meat. McDonald's nutritional information discloses that there are phosphates not only in all their chicken offerings--often two or three different kinds of phosphates--but also in their American Cheese, bacon, bacon bits, and Buttermilk Ranch Sauce.
At least McDonalds is honest enough to provide a complete listing of their ingredients online. Many fast food companies do not. Instead, they only provide the information required to be on the nutritional label, which does NOT disclose the presence or quantity of phosphates.
So What Can You Do?
Here are some steps you can take to limit the damage. The most important is this:
READ LABELS!
Once you become aware that phosphates are something you want to avoid, you may be shocked at how common they are in many foods that you have been thinking of as healthy.
After you become aware that our food supply is full of these questionable additives you can do the following:
1. Avoid drinking brown-colored diet sodas and bottled iced teas. Coke, Pepsi and Dr. Pepper usually contain phosphoric acid which the body converts into inorganic phosphates. There is solid research connecting lifetime consumption of brown sodas with a higher risk of kidney disease.
2. Read the labels on everything you buy. If you have a choice, buy the version that doesn't list phosphates. (Though that doesn't guarantee you aren't getting some.)
3. Avoid or limit consumption of rotisserie meats, chicken or other meats with added solutions. If you must eat them, keep them as occasional indulgences.
4. Avoid eating meat and chicken in fast food restaurants. There are plenty of other reasons to avoid them, a main one being the presence of MSG and hidden forms of MSG which increase hunger and promote fat gain. But steady consumption of these meats is likely to be damaging to your kidneys and heart over time.
5. Talk to your butcher or supermarket management. Ask your butcher, even at so-called Natural Foods markets, if their meats have been treated with solutions of any type. Many foods containing phosphates are marketed with labels calling them, "All Natural." If you can't get a straight answer, write to the customer service department of the company that provides branded products, like Thanksgiving Turkeys. Butterball informed me that their All Natural Turkey does not contain added inorganic phosphates.
6. Eat only unprocessed cheeses. Eat cheddar rather than American cheese, for example. Phosphates are added to most processed cheeses, even fancy ones.
7. Choose cream and half and half that doesn't have added phosphates. Phosphates are added to liguid dairy products to stop cream from floating to the surface, which consumers may think is a sign the product is spoiled. Some organic brands and the products currently sold at Trader Joe's do not have these added phosphates.
8. Read the labels on all cold cuts and bacon you buy. Don't buy the ones with phosphates--though unfortunately, you can't be entirely sure that omission from the label means omission from the food.
9. Read the labels of any supplements you buy and only buy those that don't contain added phosphates. Store brands, for example, those that copy Tums, may use other substances instead of the phosphates used in the branded products.
Phosphate, Vitamin D, and Niacin
An interesting side note to the issue of high serum phosphate is the finding that rising serum phosphates will lower Vitamin D production as Vitamin D is one of the regulators of blood phosphate levels. (Discussed HERE).
If you have abnormally low Vitamin D levels when not supplementing Vitamin D, this could be pointing to the fact that your serum phosphate level is unhealthily high.
In patients with kidney failure, there is some evidence that supplemental niacin lowers the very high serum phosphate levels characteristic of kidney failure, though there is no research to answer the question of whether niacin lowers phosphate levels in people with normal kidneys.
But it makes a lot more sense to lower serum phosphate levels by cutting out of your diet as much inorganic phosphate as possible rather than to drive with one foot on your physiological accelerator and one on the brake, which is what you do when you attempt to lower these levels by taking a supplement while consuming the phosphates.
Is Added Phosphate the Reason that Eating Red Meat is Often Linked to Heart Disease?
We have all seen the studies that link a higher consumption of red meat with heart disease. They are often pooh-poohed by advocates of meat-heavy low carb diets. But it is very possible that it is not the meat itself, but the inorganic phosphates added to the processed and fast food meats those served in fast food and chain restaurants that are causing the link between red meat consumption and heart disease.
The studies that have found this link do not distinguish between red meats cooked at home from butcher's cuts and processed meats. But since we know that there are solutions routinely added to butcher's pork which may contain phosphates, too, it is possible that even cooking your red meat at home won't solve this problem.
If you already have any signs of heart disease or kidney disease it would be a good idea to talk to your butcher and determine which meats they sell contain these added solutions so you can avoid them. If you can't get an answer, contact your supermarket's management. Explain that you have a condition which makes consuming added phosphates very dangerous and you need to know which meats they sell are safe to eat.