New research by The University of Texas Health Science Center at Houston (UTHealth) and published in the American Journal of Clinical Nutrition, found no significant link between dairy fats and cause of death or, more specifically, heart disease and stroke – two health problems often associated with a diet high in saturated fat. In fact, certain types of dairy fat may help guard against having a severe stroke, the researchers reported.

“Our findings not only support, but also significantly strengthen, the growing body of evidence which suggests that dairy fat, contrary to popular belief, does not increase risk of heart disease or overall mortality in older adults. In addition to not contributing to death, the results suggest that one fatty acid present in dairy may lower risk of death from cardiovascular disease, particularly from stroke,” said Marcia Otto, Ph.D., the study’s first and corresponding author and assistant professor in the Department of Epidemiology, Human Genetics and Environmental Sciences at UTHealth School of Public Health.

Dariush Mozaffarian, M.D., of the Friedman School of Nutrition Science and Policy at Tufts University, was senior author of the study, funded by the National Institutes of Health.

Taking a long-term view

Nearly 3,000 adults age 65 years and older were included in the study, which measured plasma levels of three different fatty acids found in dairy products at the beginning in 1992 and again at six and 13 years later.

The study evaluated how multiple biomarkers of fatty acids present in dairy fat (specifically phospholipid pentadecanoic, heptadecanoic, or trans-palmitoleic acids) related to heart disease and all-cause mortality over a 22-year period. This measurement methodology, as opposed to the more commonly used self-reported consumption, gave greater and more objective insight into the impact of long-term exposure to these fatty acids, according to the report.

None of the fatty acid types were significantly associated with total mortality. In fact one type was linked to lower cardiovascular disease deaths. People with higher fatty acid levels, suggesting higher consumption of whole-fat dairy products, had a 42 percent lower risk of dying from stroke.

Dietary advice needs revising

Dietary Guidelines for the US, the UK and elsewhere recommend serving fat-free or low-fat dairy, including milk, cheese, yogurt, and/or fortified soy beverages. But Otto pointed out that low-fat dairy foods such as low-fat yogurt and chocolate milk often include high amounts of added sugars, which may lead to poor cardiovascular and metabolic health.

“Consistent with previous findings, our results highlight the need to revisit current dietary guidance on whole fat dairy foods, which are rich sources of nutrients such as calcium and potassium. These are essential for health not only during childhood but throughout life, particularly also in later years when undernourishment and conditions like osteoporosis are more common,” Otto said.

While not everyone may choose to eat dairy products, those who do can do so with more confidence.

Evidence-based research is key to educating people about nutrition, Otto said.

“Consumers have been exposed to so much different and conflicting information about diet, particularly in relation to fats,” she said. “It’s therefore important to have robust studies, so people can make more balanced and informed choices based on scientific fact rather than hearsay,” she added.

Once again we see evidence that not all fats are created equal; and, of course, the link between fat consumption and heart disease has taken repeated knocks in recent years. In addition it’s important to note that dairy products are only one part of a healthy, varied diet. If your diet is very high in fat from all sources it may be time for a review and to opt for a more balanced way of eating.  If your diet is relatively low in total saturated fat and you enjoy full fat dairy products you can consume them knowing that they are not going to be a health risk.

To make your dairy product choices healthier still don’t forget to choose organic!

A new meta-analysis looked at studies published between 1982 and 2015 on the relationship between egg intake and coronary heart disease and stroke. In total the studies, which took place in the US, Japan, Australia, Spain and the UK monitored more than half a million people over periods of anywhere from 6 to 26 years

Specifically the researchers compared high egg intake of about one egg per day with low egg intake of less than two eggs per week. The US research team from the EpidStat Institute in Michigan found no association with heart disease but found a significant 12% reduction in stroke risk with a high intake of eggs (up to 1 egg a day). This was seen for fatal stroke, ischemic stroke and haemorrhagic stroke.

Results were published in the Journal of the American College of Nutrition.

Cholesterol controversy

Eggs contain cholesterol; around 186 mg per egg. For years this has created controversy about whether to recommend them as a healthy food.

The  UK’s National Health Service advises people eating a balanced diet to cut down on eggs only if they have been told to do so by their medical doctor or dietitian and the National Institute for Health and Care Excellence (NICE) in the UK says those at high risk of or with cardiovascular disease should consume no more than 300 mg per day of dietary cholesterol.

At the same time the American Heart Association recommends healthy adults limit dietary cholesterol intake to no more than an average 300 mg per day. Other recommendations have advised individuals at high risk of cardiovascular disease to keep this below 200 mg.

However earlier this year a study from the University of Eastern Finland also found that a relatively high intake of dietary cholesterol, or eating one egg every day, was not associated with an elevated risk of coronary heart disease.

Proving history wrong

The researchers behind the current study note that the long-assumed link between cholesterol and heart disease has itself come under fire recently.

“… a growing number of guidance committees suggest that there should be no restrictions on dietary cholesterol intake.” they write “Eggs are a nutrient-dense food, providing a good and affordable source of protein, essential fatty acids, antioxidants, choline, vitamins, and minerals. Thus, recommendations regarding the consumption of eggs should consider them as a whole food.”

Indeed eggs are an excellent source of nutrients such as protein, folate, iodine and vitamins D, A, B2 and B12 as well as lutein and zeaxanthin in the yolk.

In a recent interview Dr Ioannis Zabetakis, lecturer in food lipids at the University of Limerick, debunked the idea that lowering cholesterol was the be all and end all of heart health: “It doesn’t matter what your cholesterol levels are as long as you have anti-inflammatory foods in your diet. Once you stop inflammation it is like constructing a huge wall against a plethora of diseases,”

In addition, as important as a varied diet is, how eggs are cooked is also influential. Poached eggs on toast is a very different and healthier way to enjoy eggs than a traditional greasy fry up.

• For more on this topic see our article The incredible, edible egg.
• To learn more about inflammation see our article Q&A: How do I know if I have chronic inflammation?

This finding can help reduce the brain damage caused by stroke – which is the second leading cause of death worldwide.

In the study from Weill Cornell Medicine, published in Nature Medicine, the microbiome of mice was altered by a combination of antibiotics. Two weeks later, the researchers induced the most common type of stroke, called ischemic stroke, in which an obstructed blood vessel prevents blood from reaching the brain.

The animals treated with antibiotics experienced a stroke that was about 60% smaller than those whose microbiomes was not altered.

The research findings suggest that the microbial environment in the gut directed the immune cells there to protect the brain shielding it from the stroke’s full force.

A gut-brain connection

Further investigation is needed to understand exactly which bacterial components were protective. However, the researchers do know that the bacteria did not interact with the brain directly through chemical communication, but rather influenced neural survival by modifying the behaviour of immune cells. Immune cells from the gut made their way to the outer coverings of the brain, called the meninges, where they organised and directed a response to the stroke.

“One of the most surprising findings was that the immune system made strokes smaller by orchestrating the response from outside the brain, like a conductor who doesn’t play an instrument himself but instructs the others, which ultimately creates music,” said researcher Dr. Costantino Iadecola, director of the Feil Family Brain and Mind Research Institute and the Anne Parrish Titzell Professor of Neurology at Weill Cornell Medicine.

Dietary intervention safer

The findings are encouraging because we desperately need new ways to prevent and treat stroke, given the long list of once-promising drug candidates that have failed to help stroke patients.

Modifying the microbiotic makeup of the gut could become an innovative method of prevention and help to lessen the damage caused by stroke and could be especially useful to high-risk patients, such as those undergoing cardiac surgery or those who have multiple obstructed blood vessels in the brain.

The glimpses into the connection between the gut and the brain holds promising implications for preventing stroke in the future, which the investigators say might best be achieved by using probiotic supplements and/or changing dietary habits in patients or “at risk” individuals rather than dosing them up with antibiotics – which would be both risky and unnecessary.

“Dietary intervention is much easier to accomplish than drug use, and it could reach a broad base,” said lead researcher Dr. Josef Anrather, an associate professor of neuroscience at Weill Cornell Medicine. “This is a little far off from the current study – it’s music of the future. But diet has the biggest effect of composition of microbiota, and once beneficial and deleterious species are identified, we can address them with dietary intervention.”

Vitamin C is abundant in fruits and vegetables such as oranges, papaya, peppers, broccoli and strawberries. It is also available in supplement form. Haemorrhagic stroke is less common than ischaemic stroke, but is more often deadly.

The results of this small study have been released prior to publication, and are due to be presented at the upcoming American Academy of Neurology’s 66th Annual Meeting in Philadelphia.

To understand the effects of Vitamin C the  researchers compared 65 people who had experienced an intracerebral heamorrhagic stroke, or a blood vessel rupture inside the brain to 65 healthy people.

Participants were tested for the levels of vitamin C in their blood. In 41% of cases the subjects had normal levels of vitamin C, but 45% showed depleted levels of vitamin C and 14% were considered deficient in this nutrient.

Vitamin C deficiency a risk factor

Those who had a stroke were more likely to have depleted levels of vitamin C, while those who had not had a stroke tended to have normal levels.

“Our results show that vitamin C deficiency should be considered a risk factor for this severe type of stroke, as were high blood pressure, drinking alcohol and being overweight in our study,” said study author Stéphane Vannier, MD, with Pontchaillou University Hospital in Rennes, France.

“More research is needed to explore specifically how vitamin C may help to reduce stroke risk. For example, the vitamin may regulate blood pressure.”

Vannier adds that vitamin C appears to have other benefits like creating collagen, a protein found in bones, skin and tissues.Vitamin C deficiency has also been linked to heart disease.

Building on previous research

Past studies have also linked vitamin C with reduced stroke risk.

In 2013 a meta-analysis showed that as blood levels of vitamin C went up, stroke risk dropped; those with the highest levels had around a 38% reduced risk of stroke. A 2008 University of Cambridge study found people with high blood levels of vitamin C reduced their stroke risk by 42%. A similar study in the British Medical Journal in 1995 indicated elderly people with low levels of the vitamin had a greater risk of stroke.

This research add to the long list of benefits from adequate vitamin C including its ability to support immunity. The body cannot make vitaamin C and so we need to get it from our diets every day. Recommended doses for adult men and women are 90 and 75 milligrams (mg) per day, respectively, though women need more during pregnancy and breastfeeding.

Previous research has yielded conflicting findings about whether taking vitamin B supplements affects the risk of stroke and heart attack. Some studies have concluded that taking vitamin B supplements could actually increase the risk, according to the review authors.

To find a definitive answer Chinese researchers analysed the findings of 14 high quality clinical trials that included a total of more than 55,000 people. 

All of the trials compared vitamin B supplement use with a placebo or very low-dose vitamin B.

The participants were followed for a minimum of six months. There were a total of nearly 2,500 strokes among the participants in the studies, all of which showed some benefit of taking vitamin B.

Though the findings of individual studies varied, overall they found that vitamin B supplements reduced the risk of stroke by 7%. However, supplementing with B vitamins but did not appear to reduce the severity of strokes or the risk of death from stroke, according to the review, which was published in the online edition of the journal Neurology.

Biological basics

Two forms of B vitamins – folic acid and B12 – were particularly influential.

Folate (B9) and cobalamin (B12) are important regulators of homocysteine metabolism; high levels of homocysteine are a risk factor for heart disease and stroke. In several countries cereals are fortified with folic acid which is a supplemental form of folate.

The researchers found that folic acid appeared to reduce the beneficial effect of vitamin B. They also found that vitamin B12 had no effect on stroke risk unless there was a pre-existing deficiency.

Several biological factors, however, may affect whether vitamin B supplements will affect stroke risk and these may account for conflicting results between apparently similar studies.

“Based on our results, the ability of vitamin B to reduce stroke risk may be influenced by a number of other factors, such as the body’s absorption rate, the amount of folic acid or vitamin B12 concentration in the blood, and whether a person has kidney disease or high blood pressure,” said review author Xu Yuming, of Zhengzhou University in China.

Investigating deficiencies

Because of these biological factors the researchers also suggest that it can be difficult to make broad recommendations for daily doses. Indeed in the study there seemed little difference in benefit between different doses of folic acid and B12. What mattered more was blood levels of these nutrients, especially with regard to B12.

“Our clinical implication is that metabolic B₁₂ deficiency should be more thoroughly followed and treated, so that such deficiencies are found and treated appropriately with B vitamin intervention,” the authors write. “In future, we should consider adoption of specific administration routes rather than a single oral route, e.g. oral route in populations with inadequate dietary intake or injection route in populations with B12 malabsorption to obtain effective intervention results.”

Better health checks needed

Ischemic strokes can have many different causes, the most common being hypertension, diabetes, high cholesterol, smoking and obesity,while some doctors are aware of the influence of deficiency of vitamins and enzymes, it is not always followed through in standard health checks given to patients who have suffered a stroke.

The analysis is  important because there is an increased public interest in dietary prevention of disease and these findings identify a substance which is readily available and has been demonstrated to have a positive effect in stroke risk reduction in certain individuals.

In a new study , researchers from Osaka Japan compared the risk of both ischaemic strokes (caused by blocked blood flow) and haemorrhagic strokes (caused by bleeding into the brain) to soft drink intake in nearly 40,000 Japanese men and women over an 18 year period.

For the purposes of this study soft drinks were defined as sugar-sweetened sodas and juices only.

Their findings were published in an early online edition of the American Journal of Clinical Nutrition.

Women at risk

The researchers tracked the eating and drinking habits of the study participants and split them into four groups: those who rarely drank soft drinks, those who had one to two cups a week, those who had three to four cups a week, and those who had a soft drink nearly every day.

Amongst the women, those who drank soft drinks almost every day had a 21% higher risk of developing a stroke compared to those who never or rarely drank soft drinks.

The risk of ischaemic stroke  – which is caused by plaque build-up in the arteries – was 83% higher in those who consumed soft drinks almost every day compared to those who rarely or never drank soft drinks.

In men, there was only a small increase in total strokes, ischaemic strokes, and haemorrhagic strokes. The authors were not able to explain why this should be so. There was no increased risk of ischaemic heart disease in either sex.

A trail of evidence

Previous research has shown that soft drinks are associated with a higher risk of obesity and diabetes. The relationship with heart attacks and strokes is less plentiful.

Even so, this is not the first study to reach this conclusion.  In a study published earlier this year, involving more than120,000 men and women, US researchers found drinking a single soda each day increased the risk of ischemic stroke.

In addition, the study found that men and women who consumed more than one serving of sugar-sweetened soda per day had higher rates of high blood pressure and were also more likely to have a generally unhealthy lifestyle (though factoring this in didn’t alter the stroke risk associated with soda consumption).

According to the researchers sodas are the largest sources of added sugar in the diet. Regular intake sets off a ‘chain reaction’ in the body that can potentially lead to many diseases, including stroke. (For an interesting graphic that explores Your Body on Soda, see here).

Interestingly the Japanese study did not take diet sodas, or 100% fruit juices into account. However, earlier this year the frequent consumption of diet soda was also linked to a greater likelihood stroke.

The study, published in the journal Neurology, found that those with the highest amounts of lycopene in their blood were 55% less likely to have a stroke than those with the lowest amounts.

The study involved 1,031 men in Finland between the ages of 46 and 65. The level of lycopene in their blood was assessed at the start of the study and they were followed for an average of 12 years. During that time, 67 men had a stroke.

Among the men with the lowest levels of lycopene, 25 of 258 men had a stroke. Among those with the highest levels of lycopene, 11 of 259 men  (56% fewer) had a stroke. When researchers looked at just strokes due to blood clots, the results were even stronger. Those with the highest levels of lycopene were 59% less likely to have a stroke than those with the lowest levels.

The study also found  that smokers tended to have the lowest blood levels of lycopene. Smoking is a major risk factor for stroke.

“This study adds to the evidence that a diet high in fruits and vegetables is associated with a lower risk of stroke,” said study author Jouni Karppi, PhD, of the University of Eastern Finland in Kuopio. “The results support the recommendation that people get more than five servings of fruits and vegetables a day, which would likely lead to a major reduction in the number of strokes worldwide, according to previous research.”

Lycopene was uniquely protective

The study also looked at blood levels of the antioxidants alpha-carotene, beta-carotene, alpha-tocopherol and retinol, but found no association between the blood levels of these nutrients and risk of stroke.

The reason carotenoids in general might be expected to have an effect on stroke risk is that they help mediate the damage that free radicals, unstable molecules that are formed as part of normal metabolism, but also in the presence of toxins such as cigarette smoke, can cause  to vital organs and tissues as well as blood vessels and nerves.

“One possible reason that lycopene might decrease the risk of stroke more than other antioxidants…may be the consequence of antioxidant activity,” write the researchers. Lycopene is a potent antioxidant and in this study was more effective than beta-carotene in protecting cells against a variety of differently types of free radicals.

Turn up the heat

While many beneficial nutrients are heat-sensitive, when a tomato is cooked, the heat processing actually increases the levels of cis-lycopene, which is easily absorbed by the body.

As a result cooked tomatoes and tomato products tend to have a greater effect on blood levels of lycopene than raw tomatoes or tomato juice.

Lycopene in the diet also has other functions such as reducing inflammation, blocking cholesterol synthesis, boosting immune function, and inhibiting platelet aggregation and thrombosis.

Other studies have shown that high lycopene levels may be linked to a reduced risk of certain cancers.

For instance a review in 2011 found that eating more tomatoes and tomato products can make people healthier and decrease the risk of conditions such as cancer, osteoporosis and cardiovascular disease, according to a review article the American Journal of Lifestyle Medicine.

Earlier this year a study in the British Journal of Nutrition found that the lycopene in cooked tomatoes slowed the growth of or even kill prostate cancer cells. The scientists found that lycopene intercepts cancer’s ability to make the connections it needs to attach to a healthy blood supply.

Tomatoes are not the only food that is rich in lycopene. Other sources include pink grapefruit, watermelon,  guava, papaya, sea buckthorn berries, wolfberries (goji berries) and rosehips.

The food with the highest levels of lycopene is actually the gac – a vine fruit native to Southeast Asia which is not usually available outside that region. Some healthfood shops sell antioxidant dietary supplements and juices containing gac.