Vitamin D and Alzheimer’s Disease

Unfortunately there is currently an absence of curative and preventative interventions for Alzheimer’s Disease (AD). Last year, Panza et al. reviewed the research on the links between vitamin D and AD. Low vitamin D levels have been associated with an accelerated decline in cognitive functions. They have also been associated with the development of chronic brain conditions such as AD and other dementias. As such, vitamin D is often thought of as a neurosteroid due to its effect on brain conditions. The authors believe more research is required to determine the effect of vitamin D supplementation on the prevention and/or treatment of AD.

Eating For Health And Longevity

Valter Longo et al. recently published a paper that examined research on the relationships between nutrition, health and longevity. Here are some of the main components of a longevity diet:

  • mid to high carbohydrate intake (45-60%) – mostly non-refined
  • fat intake (25-35%) – mostly plant-based
  • low protein intake (10-15%) – mostly plant-based but includes regular consumption of peso-vegetarian-derived proteins. Low protein intake or normal protein intake (with high legume consumption) lowers the intake of amino acids such as methionine. This in turn lowers pro-aging substances such as GHR, IGF-1, insulin and TOR-S6K.
  • over 65s need to be careful to avoid malnourishment and prevent frailty and diseases resulting from reduced muscle mass, reduced bone mass or low blood cell count.
  • the largest gains in longevity come from diets rich in legumes, whole grains and nuts. With reduced amounts of red meat and processed meats
  • a 12-13hr daily fasting period is key to reducing the insulin resistance that may have developed from a high calorie diet. The fasting window also helps decrease levels of IGF-1, lowers blood pressure, lowers total cholesterol and decreases inflammation.
  • our daily food intake should be established by our body fat/lean body mass composition rather than generic pre-set calorie amounts.

Nutrition, Immunity and COVID-19

Our immune system protects us from pathogens like viruses, bacteria, cancerous cells, etc. and it can be separated into 2 distinct branches: the innate immune system and the adaptive immune system. Our innate immune system uses cells such as macrophages, neutrophils and mast cells to mount a fast, generic response to pathogens. Inflammation is the hallmark of the innate immune system. On the other hand, the adaptive immune system uses T cells, B cells and natural killer cells to mount a slow, targeted response to pathogens. It’s the adaptive immune system that’s responsible for life-long immunity to certain diseases. In practice, the 2 branches interact to provide a comprehensive immune response.

In a recent article, Butler and Barrientos (2020) summarised the interactions between diet, immunity and COVID-19. They state that the typical western diet (high in saturated fats, refined carbohydrates and sugars, and low in fibre, unsaturated fats and antioxidants) “significantly impairs adaptive immunity while ramping up innate immunity, leading to chronic inflammation and severely impairing host defence against viral pathogens.

The authors note that “T and B cell counts were also significantly lower in patients with severe COVID-19; thus, there could be a potential interaction between western diet consumption and COVID-19 on adaptive immunity impairment.” They suggest the higher rates of obesity and diabetes among ethnic minority populations may partly account for the health disparities seen in response to COVID-19.

Butler and Barrientos conclude “that individuals refrain from eating foods high in saturated fats and sugar and instead consume high amounts of fibre, whole grains, unsaturated fats, and antioxidants to boost immune function.”

Early Feeding Improves Pre-Diabetes and Blood Pressure

About a year ago Sutton et al. published a study that showed that intermittent fasting has benefits that are independent of food intake and weight loss. Their trial tested the effects of 5 weeks of “early time-restricted feeding” (eTRF) on 8 men with pre-diabetes. The subjects were asked to start breakfast between 6:30-8:30 and to eat their 3 meals in a 6-hour window with dinner before 15:00. They were fed enough food to maintain weight. The control group had similar meals but within a 12-hour feeding window. Five weeks of eTRF significantly improved insulin levels, insulin sensitivity, blood pressure and oxidative stress levels. The blood pressure improvements were particularly dramatic – morning levels of both systolic and diastolic blood pressure were reduced by about 10 mm Hg each.

Some of the benefits of eTRF are believed to originate from eating in alignment with our internal biological clocks which are primed for feeding early in the day. The authors state that “in humans, insulin sensitivity, beta cell responsiveness, and the thermic effect of food are all higher in the morning than in the afternoon or evening, suggesting that human metabolism is optimized for food intake in the morning”. Fortunately eTRF lowers the desire to eat in the evening!

Meal Times Crucial For Weight Loss

A few months ago Lopez-Minguez et al. reviewed studies looking at the effect of meal times on obesity and metabolic risk. Their findings are summed up in the following points:

  • skipping breakfast is linked to obesity
  • eating a large breakfast (within 2hrs of waking) decreases the probability of being obese by 50%
  • a late lunch (after 3pm) hampers weight loss and has a negative effect on the diversity and composition of our microbiota
  • a late dinner (less than 2hrs before bedtime) decreases glucose tolerance
  • eating a large, late dinner (less than 2hrs before bedtime) leads to a 5-fold increase in the risk of becoming obese
  • the timing of breakfast seems to be hereditary whereas the timing of dinner is mainly cultural

There may be some truth in the following quote by Adelle Davis.

Eat breakfast like a king, lunch like a prince and dinner like a pauper

As well as getting the timing right obviously!

Excess Dietary Salt Leads To Cognitive Impairment

Faraco et al. recently discovered mechanisms by which salt-rich diets can lead to cognitive dysfunction in mice. An increase in dietary salt led to a deficiency of nitric oxide in cerebral blood vessels. As nitric oxide is a vasodilator, the reduced levels resulted in decreased cerebral blood flow. In addition, nitric oxide deficiency causes the distortion of a brain protein (tau) which affects the structure and function of nerve cells. The authors conclude that the “avoidance of excessive salt intake and maintenance of vascular health may help stave off the vascular and neurodegenerative pathologies that underlie dementia in the elderly.”

Paleo Diet May Be Bad For Cardiovascular Health

Research published earlier this month in the European Journal of Nutrition questions the health benefits of the Paleolithic diet. The Paleo diet claims to mimic the diet of our ancestors. It’s high in meat, fruits, vegetables, nuts and seeds but avoids dairy, legumes and grains.

Genoni et al. studied a group of about 100 people over a year. Half the group followed a Paleo diet and the rest followed a diet typical of national recommendations. The authors found that there was a significant difference in the gut bacteria between groups, with an increased presence of Hungatella in the paleo group. Hungatella produces trimethylamine-N-oxide (TMAO), a gut-derived metabolite associated with cardiovascular disease. Consequently the levels of TMAO were higher in the Paleo group and this was inversely associated with whole grain intake.

The authors conclude that “although the Paleo diet is promoted for improved gut health, results indicate long-term adherence is associated with different gut microbiota and increased TMAO. A variety of fiber components, including whole grain sources may be required to maintain gut and cardiovascular health.”

Higher Fibre Intake Improves Health

Last month Reynolds et al. published an article in The Lancet that looked into the relationship between carbohydrate quality and health. They carried out a series of systematic reviews and meta-analyses that evaluated around 135 million person-years of data from 185 prospective studies as well as 58 clinical trials with 4635 adults. They found that those with higher intakes of fibre had lower body weight, lower systolic blood pressure and lower total cholesterol. Those with higher fibre intakes also had a decreased incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer, which may explain the 15-30% decrease in all-cause mortality between the groups with high and low fibre intake. Daily intake of fibre between 25g-30g seemed to confer the greatest risk reduction, although they note that “higher intakes of dietary fibre could confer even greater benefit“.

Low Carbohydrate Diets Are Bad For Health

Yesterday professor Banach, from the Medical University of Lodz in Poland, released the findings of his research at the European Society of Cardiology. The prospective study looked at the relationship between low carbohydrate diets, all-cause mortality and deaths specifically from coronary heart disease, stroke and cancer. The study group consisted of almost 25,000 adults from the US National Health and Nutrition Examination Survey (NHANES) from 1999 to 2010. Over an average 6.4-year follow-up, compared to the group with the highest consumption of carbohydrates, the group with the lowest consumption had an increased risk of all-cause mortality (32%) and an increased risk of death from coronary heart disease (51%), stroke (50%) and cancer (35%). These results were backed up by the findings of a meta-analysis of several studies involving close to 450,000 people.

Professor Banach said: “Low carbohydrate diets might be useful in the short term to lose weight, lower blood pressure, and improve blood glucose control, but our study suggests that in the long-term they are linked with an increased risk of death from any cause, and deaths due to cardiovascular disease, cerebrovascular disease, and cancerThe reduced intake of fibre and fruits and increased intake of animal protein, cholesterol, and saturated fat with these diets may play a role. Differences in minerals, vitamins and phytochemicals might also be involved. Our study highlights an unfavourable association between low carbohydrate diets and total and cause-specific death, based on individual data and pooled results of previous studies. The findings suggest that low carbohydrate diets are unsafe and should not be recommended.

Plant-Based Diets Improve Health

Last month “Nutrition 2018” was held in Boston. It was the inaugural flagship meeting of the American Society for Nutrition. Evidence from several studies was presented showing that a primarily plant-based diet is linked to numerous health benefits. Obviously, the quality of the food was important as well. Here is a summary of 5 papers that were presented:

  • A 13 year study of 6000 people in the Netherlands found that a higher proportion of dietary plant protein to animal protein was linked to lower risks of developing heart disease.
  • A study of 4500 Brazilians showed that those eating more plant-based protein were 60% less likely to have coronary artery plaque than those consuming more animal-based protein.
  • South Asians living in the US that followed a vegetarian diet had a lower number of risk factors for heart disease and diabetes (lower body mass index, smaller waist circumference, less abdominal fat, lower cholesterol levels, lower blood sugar levels) than those that ate meat.
  • A 4-year American study of over 125,000 adults showed that a whole food plant-based diet (whole grains, fruits, vegetables, nuts, etc.) led to less weight gain than a processed plant-based diet (sweets, refined grains, fries, etc.).
  • A study on 30,000 American adults demonstrated that improving the quality of the plant-based component of diet decreased mortality by 30% whereas improving the quality of the animal-based components had little effect. Among people with chronic health problems these beneficial effects were even more pronounced.

These recent research findings add to the mounting body of evidence supporting the health benefits of a whole food plant-based diet.