Diet And Metabolic Syndrome

Metabolic syndrome affects at least one in five adults with some estimates putting its prevalence as high as one in three. Why does it matter? Because having metabolic syndrome has been described as a ‘cardiovascular time-bomb’. Metabolic syndrome is associated with a  five-fold risk of developing type 2 diabetes. It also doubles your risk of a heart attack or stroke, and is associated with a 1.5 times increase in the risk of dying from any medical cause, including kidney disease and specific cancers, compared to someone without metabolic syndrome.

The good news is that metabolic syndrome is entirely reversible through diet and lifestyle changes which include weight loss and an increased intake of protective polyphenol antioxidants.

What is metabolic syndrome?

Metabolic syndrome is signified by a combination of factors which include high blood pressure, raised triglycerides, low ‘good’ HDL-cholesterol, high fasting blood glucose levels, insulin resistance and abdominal obesity. You just need three of these common factors for your doctor to diagnose metabolic syndrome.

The most easily identifiable sign of having metabolic syndrome is central obesity, in which excess fat is stored around your waist.

Find a tape-measure and check the size of your waist in centimetres.

You could have metabolic syndrome if your waist is greater than:

  • 80cm and you are female
  • 94cm and you are a white European male
  • 90cm and you are a South Asian or Chinese male.

Having a large waist is a sign that you are storing excess fat around your internal organs.

Compared with fat cells found elsewhere in the body, such as beneath the skin, those packed around your internal organs are unusually active. They ‘leak’ fatty acids into the circulation and produce a number of hormones that are associated with insulin resistance and poor glucose tolerance. These fatty acids and hormones travel straight to the liver, where they activate genes that increase the production of ‘bad’ non-HDL-cholesterol, clotting factors and inflammatory substances that increase your risk of heart attack and stroke.

Metabolic syndrome is also associated with polycystic ovary syndrome (PCOS) due to the common underlying factor of insulin resistance.

If you think you could have metabolic syndrome, see your doctor for a check-up to assess your blood pressure, cholesterol balance, triglyceride and glucose levels. You may need medication to correct these while you embark on weight loss and exercise regime to reverse these abnormalities and get back to health.

Metabolic syndrome and your resting heart rate

Having metabolic syndrome is associated with a raised resting heart rate. The results from 17 studies, involving

169,786 people, suggest that every 10 beats per minute increase in resting heart beat increases the risk of having metabolic syndrome by 28%. This association may be due to effects of abnormal metabolism on the central nervous system, or may simply reflect the fact that people who are overweight with a high blood pressure or diabetes may be less physically fit and therefore have a lower resting heart rate than those without metabolic syndrome.

The link between obesity and metabolic syndrome

Metabolic syndrome is strongly associated with obesity and the development of insulin resistance.

Insulin hormone acts as the key to unlock the gates through which circulating glucose can enter muscle and fat cells. Once inside muscle cells, glucose is either burned as a fuel or converted into a starchy storage molecule called glycogen. Within fat cells, excess glucose is converted into fatty acids and glycerol which combine to form triglycerides. Some free fatty acids and triglycerides are sent out into the circulation, but most stay put and are stored as white fat.

As white fat builds up within fat cells, they may stop responding to insulin and become increasingly resistant in order to avoid dealing with more and more fat when they are already over laden. The tendency towards insulin resistance may be inherited or acquired due to lifestyle factors such as lack of exercise and eating excessive amounts of carbohydrates.

Once muscle and fat cells lose their sensitivity to insulin hormone, your blood glucose levels stay higher than normal after eating carbohydrate. Your pancreas tries to overcome this by making more and more insulin in an attempt to push this excess glucose into your fat cells for storage. This sets up a vicious circle in which your waistline gets bigger and bigger, your cells become less and less sensitive to insulin, and your insulin and glucose levels keep rising.

Metabolic syndrome and fatty liver

When muscle and fat cells become resistant to the effects of insulin, glucose can’t escape into them and glucose levels rise within the circulation. Some glucose can still enter liver cells, however, where it is converted into fat. Liver cells may also continue to make new glucose (eg from dietary protein) as a result of insulin resistance.

Fat builds up within liver cells and the liver undergoes the same fatty changes seen in the French ducks and geese that are overfed on grain to produce pâté de fois gras.

Metabolic syndrome and the brain

Brain cells preferentially use glucose as a fuel, so excess glucose continues to enter brain cells. This excess glucose can damage the brain to cause inflammation. Having metabolic syndrome is now recognised as a risk factor for several types of dementia.

Metabolic syndrome and weight loss

Weight loss can improve all of the cardiovascular risk factors seen in people with metabolic syndrome – just losing 4kg to 7kg in weight can make a significant difference.

Losing 10 kg (22lb) in excess weight can:

  • Lower blood pressure by 10/20 mmHg
  • Improve fasting blood glucose levels by 50%
  • Reduce blood levels of triglyceride fat by 30%
  • Improve cholesterol balance by reducing total cholesterol by 10%, ‘bad’ LDL-cholesterol by 15% while increasing ‘good’ HDL-cholesterol – the one you want more of – by at least 8%.

As a result, for someone who is obese, losing 10kg can reduce their overall risk of premature death by 20% and their risk of a diabetes-related death by as much as 30%.

Metabolic syndrome and SIRT1

The cell signal that increases insulin resistance to trigger metabolic syndrome is not yet fully understood, but a number of substances produced by fat stores are possible candidates, including one called ‘resistin’.

Resistin significantly reduces the production and activity of a gene which makes a protein called SIRT1, which may be the missing link between obesity, insulin resistance and metabolic syndrome.

SIRT1 acts as a master conductor that orchestrates all the different prongs of metabolism at both the cellular and whole body level. SIRT1 stimulates the breakdown and burning (oxidation) of fat and cholesterol in liver cells, fat cells and skeletal muscles.

One of its roles is to increase the number and size of a cell’s energy-producing cell structures, known as mitochondria. For example, a skeletal muscle cell in your thigh typically contain around 2000 mitochondria, but when you start a sustained exercise program, their number and size increases. As the mitochondria are where fat is burned to produce energy, this effect in building bigger, more numerous mitochondria means that SIRT1 is one of the key links between regular exercise and effective weight loss.

SIRT1 also has an effect on special nerve cells (pro-opiomelanocortin neurons) found in a part of the brain known as the hypothalamus. These cells respond to the appetite-suppressing hormone, leptin.

Leptin is release by fat cells in an attempt to reduce your food intake. The amount of leptin you make is directly related to the size of your fat stores, so you’d expect that the more you weigh, the fuller you’d feel. Here’s the catch: As you get more and more overweight, leptin receptors in the appetite control centre of your brain become less and less responsive to its effects so the signal that usually stops you eating doesn’t get through. SIRT1 helps to overcome this by ensuring the satiety signal that stops you eating gets through.

SIRT1 therefore plays a critical role in suppressing appetite and reducing energy intake to support weight loss, help maintain a normal body weight and in maintaining healthy blood glucose levels.

SIRT1 also promotes the transportation of cholesterol back from the circulation to the liver for processing.

This makes SIRT1 particularly important for weight loss and to improve cholesterol balance in people with metabolic syndrome.

SIRT1 activating foods  

Many plant foods contain antioxidant polyphenols which can boost the activity of the SIRT1 gene to help reverse metabolic syndrome.

The most powerful SIRT1 activating polyphenols are:

Resveratrol which is found in red and black grapes, red (and white) wine, peanuts, pistachios, blueberries, lingonberries, cranberries, redcurrants, strawberries, cocoa and dark chocolate.

Quercetin which is found in capers, buckwheat, peppers, cocoa, dill weed, red grapes, dark cherries, cruciferous vegetables such as broccoli, cabbage and sprouts, green leaves such as rocket/arugula, spinach and kale, onions, tomatoes, apples, berries, citrus fruit and beans.

Heating – especially boiling in water – significantly reduces the amount of quercetin available for absorption. Aim to eat quercetin-rich fruit and vegetables either raw or only lightly cooked.

SIRT1 activating foods explain many of the heart benefits of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets.

Resveratrol and metabolic syndrome

Resveratrol is one of the most potent natural SIRT1 activators known, although other polyphenols that are less prevalent in the diet (eg pterostilbene, luteolin) and piceatannol (a breakdown product of resveratrol) are now known to have even more powerful effects.

Doses of resveratrol that are significantly higher than is found in the diet – equivalent to the amount found in three hundred or more glasses of Chianti! – are needed to obtain beneficial effects in metabolic syndrome.

For example, six studies, involving almost 250 people, show that resveratrol at high doses (150mg per day) has a beneficial effect on blood vessel dilation to significantly lower systolic blood pressure (upper reading) by 11.9 mmHg in people with hypertension. Smaller doses did not have an effect.

Resveretrol supplements also lowered total cholesterol level and fasting glucose in people who were overweight or obese. When added to normal drug treatment in people with type 2 diabetes, resveratrol supplements were more effective than placebo in reducing systolic blood pressure and HbA1c – a measure of glucose control.

Quercetin and metabolic syndrome

Quercetin is a powerful antioxidant that reduces inflammation and can boost weight loss, especially in people with metabolic syndrome.

Early studies suggested that quercetin was a powerful SIRT1 activator, but a later study using a new method suggested that quercetin was, in fact, three times less active as a SIRT1 activator than resveratrol. However, quercetin has another important action, in that it directly stimulates the growth and division of mitochondria to boost the amount of fat your cells can burn. Quercetin also switches off some genes needed for fat storage, and switches on other genes so that levels of SIRT1 increase by around 60%.

Quercetin has many beneficial effects on energy metabolism to suppress fat formation, reduce insulin resistance and improve glucose tolerance.

Quercetin has beneficial effects on insulin resistance, promoting the uptake and disposal of glucose within fat cells, boosting the number and activity of mitochondria so that more glucose is burned to produce heat and energy rather than stored as fat.

As a powerful antioxidant, quercetin protects circulating LDL-cholesterol from the oxidation that triggers atherosclerosis.

A good intake of dietary flavonoids, including quercetin, helps to reduce hardening and furring up of the arteries (atherosclerosis) that can lead to heart attack or stroke. Research suggests that much of the protection against atherosclerosis is due to activation of SIRT1 in the cells lining blood vessel walls.

All these beneficial effects can occur at quercetin intakes found within the Mediterranean diet, without the need for supplements.

In fact, quercetin levels equivalent to those produced from good dietary intakes can suppress the formation of triglycerides within fat cells by as much as 42%. Higher intakes are needed to suppress the laying down of fat in mature fat cells, however.

Diet and metabolic syndrome

When you have glucose intolerance and insulin resistance, it’s important to follow a diet with contains lower amounts of sugar and carbohydrates than you are probably used to.

This means following a lower glycemic index diet, which contains more healthy fats and protein, along with SIRT1 activating foods that boost your metabolism, increase fat burning and help you lose weight.

The Mediterranean diet (go easy on pizza dough and pasta) is key. The results of 12 studies, involving 33,847 people, of whom 6342 had metabolic syndrome, shows that following a Mediterranean-style diet was associated with a 19% lower risk of developing metabolic syndrome than other patterns of eating.

A modified Mediterranean style diet, which is also low in salt, was developed to treat people with high blood pressure. Known as the DASH (Dietary Approach to Stop Hypertension) diet, it was found to reduce blood pressure by 4.9/1.9 mmHg in people with metabolic syndrome, and controlled hypertension in 75%.

You can find out how to follow a DASH diet and download a DASH Diet food list HERE.

Avoid sweetened drinks

Avoid sugar-sweetened and artificially sweetened drinks as both are associated with metabolic syndrome. This may reflect the fact that soft drinks are a good indicator of following a generally unhealthy diet and lifestyle.

Supplements for Metabolic Syndrome

A number of supplements can help people with metabolic syndrome. As a basic, most people benefit from taking a multivitamin and mineral supplement as magnesium, selenium, copper, zinc, vitamin C and vitamin E which are all important for improving glucose tolerance.

  • Chromium helps to regulate blood sugar levels by improving insulin resistance in muscle cells. It may only help people who are chromium deficient but, as this is relatively common, there is little harm in trying a chromium supplement at a dose of 200mcg daily for a few months to see if it helps.
  • Alpha-lipoic acid helps to improve insulin sensitivity and glucose uptake into muscle cells.
  • Conjugated linoleic acid helps to improve insulin resistance in fat cells.
  • Coenzyme Q10 (ubiquinol 100mg) may improve the function of insulin-producing cells in the pancreas.
  • Pycnogenol (maritine pine bark extract) has been found to improve glucose tolerance through a mechanism that is not yet fully understood.
  • Globe artichoke can improve fatty liver.
  • Vitamin E supplements may be needed to maintain levels in metabolic syndrome.
  • Supplements that can improve blood pressure are covered here.
  • Herbal medicines that can improve type 2 diabetes glucose control are covered here.

Image credits: pat_hastings/bigstock

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